--- /dev/null
+/*
+ * Public API and common code for kernel->userspace relay file support.
+ *
+ * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
+ * Copyright (C) 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * Moved to kernel/relay.c by Paul Mundt, 2006.
+ * November 2006 - CPU hotplug support by Mathieu Desnoyers
+ * (mathieu.desnoyers@polymtl.ca)
+ *
+ * This file is released under the GPL.
+ */
+#include <linux/errno.h>
+#include <linux/stddef.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/ltt-relay.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/splice.h>
+#include <linux/bitops.h>
+
+/* list of open channels, for cpu hotplug */
+static DEFINE_MUTEX(relay_channels_mutex);
+static LIST_HEAD(relay_channels);
+
+/**
+ * relay_alloc_buf - allocate a channel buffer
+ * @buf: the buffer struct
+ * @size: total size of the buffer
+ */
+static int relay_alloc_buf(struct rchan_buf *buf, size_t *size)
+{
+ unsigned int i, n_pages;
+ struct buf_page *buf_page, *n;
+
+ *size = PAGE_ALIGN(*size);
+ n_pages = *size >> PAGE_SHIFT;
+
+ INIT_LIST_HEAD(&buf->pages);
+
+ for (i = 0; i < n_pages; i++) {
+ buf_page = kmalloc_node(sizeof(*buf_page), GFP_KERNEL,
+ cpu_to_node(buf->cpu));
+ if (unlikely(!buf_page))
+ goto depopulate;
+ buf_page->page = alloc_pages_node(cpu_to_node(buf->cpu),
+ GFP_KERNEL | __GFP_ZERO, 0);
+ if (unlikely(!buf_page->page)) {
+ kfree(buf_page);
+ goto depopulate;
+ }
+ list_add_tail(&buf_page->list, &buf->pages);
+ buf_page->offset = (size_t)i << PAGE_SHIFT;
+ buf_page->buf = buf;
+ set_page_private(buf_page->page, (unsigned long)buf_page);
+ if (i == 0) {
+ buf->wpage = buf_page;
+ buf->hpage[0] = buf_page;
+ buf->hpage[1] = buf_page;
+ buf->rpage = buf_page;
+ }
+ }
+ buf->page_count = n_pages;
+ return 0;
+
+depopulate:
+ list_for_each_entry_safe(buf_page, n, &buf->pages, list) {
+ list_del_init(&buf_page->list);
+ __free_page(buf_page->page);
+ kfree(buf_page);
+ }
+ return -ENOMEM;
+}
+
+/**
+ * relay_create_buf - allocate and initialize a channel buffer
+ * @chan: the relay channel
+ * @cpu: cpu the buffer belongs to
+ *
+ * Returns channel buffer if successful, %NULL otherwise.
+ */
+static struct rchan_buf *relay_create_buf(struct rchan *chan, int cpu)
+{
+ int ret;
+ struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
+ if (!buf)
+ return NULL;
+
+ buf->cpu = cpu;
+ ret = relay_alloc_buf(buf, &chan->alloc_size);
+ if (ret)
+ goto free_buf;
+
+ buf->chan = chan;
+ kref_get(&buf->chan->kref);
+ return buf;
+
+free_buf:
+ kfree(buf);
+ return NULL;
+}
+
+/**
+ * relay_destroy_channel - free the channel struct
+ * @kref: target kernel reference that contains the relay channel
+ *
+ * Should only be called from kref_put().
+ */
+static void relay_destroy_channel(struct kref *kref)
+{
+ struct rchan *chan = container_of(kref, struct rchan, kref);
+ kfree(chan);
+}
+
+/**
+ * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
+ * @buf: the buffer struct
+ */
+static void relay_destroy_buf(struct rchan_buf *buf)
+{
+ struct rchan *chan = buf->chan;
+ struct buf_page *buf_page, *n;
+
+ list_for_each_entry_safe(buf_page, n, &buf->pages, list) {
+ list_del_init(&buf_page->list);
+ __free_page(buf_page->page);
+ kfree(buf_page);
+ }
+ chan->buf[buf->cpu] = NULL;
+ kfree(buf);
+ kref_put(&chan->kref, relay_destroy_channel);
+}
+
+/**
+ * relay_remove_buf - remove a channel buffer
+ * @kref: target kernel reference that contains the relay buffer
+ *
+ * Removes the file from the fileystem, which also frees the
+ * rchan_buf_struct and the channel buffer. Should only be called from
+ * kref_put().
+ */
+static void relay_remove_buf(struct kref *kref)
+{
+ struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
+ buf->chan->cb->remove_buf_file(buf->dentry);
+ relay_destroy_buf(buf);
+}
+
+/*
+ * High-level relay kernel API and associated functions.
+ */
+
+/*
+ * rchan_callback implementations defining default channel behavior. Used
+ * in place of corresponding NULL values in client callback struct.
+ */
+
+/*
+ * create_buf_file_create() default callback. Does nothing.
+ */
+static struct dentry *create_buf_file_default_callback(const char *filename,
+ struct dentry *parent,
+ int mode,
+ struct rchan_buf *buf)
+{
+ return NULL;
+}
+
+/*
+ * remove_buf_file() default callback. Does nothing.
+ */
+static int remove_buf_file_default_callback(struct dentry *dentry)
+{
+ return -EINVAL;
+}
+
+/* relay channel default callbacks */
+static struct rchan_callbacks default_channel_callbacks = {
+ .create_buf_file = create_buf_file_default_callback,
+ .remove_buf_file = remove_buf_file_default_callback,
+};
+
+/**
+ * wakeup_readers - wake up readers waiting on a channel
+ * @data: contains the channel buffer
+ *
+ * This is the timer function used to defer reader waking.
+ */
+static void wakeup_readers(unsigned long data)
+{
+ struct rchan_buf *buf = (struct rchan_buf *)data;
+ wake_up_interruptible(&buf->read_wait);
+}
+
+/**
+ * __relay_reset - reset a channel buffer
+ * @buf: the channel buffer
+ * @init: 1 if this is a first-time initialization
+ *
+ * See relay_reset() for description of effect.
+ */
+static void __relay_reset(struct rchan_buf *buf, unsigned int init)
+{
+ if (init) {
+ init_waitqueue_head(&buf->read_wait);
+ kref_init(&buf->kref);
+ setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);
+ } else
+ del_timer_sync(&buf->timer);
+
+ buf->finalized = 0;
+}
+
+/*
+ * relay_open_buf - create a new relay channel buffer
+ *
+ * used by relay_open() and CPU hotplug.
+ */
+static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
+{
+ struct rchan_buf *buf = NULL;
+ struct dentry *dentry;
+ char *tmpname;
+
+ tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!tmpname)
+ goto end;
+ snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
+
+ buf = relay_create_buf(chan, cpu);
+ if (!buf)
+ goto free_name;
+
+ __relay_reset(buf, 1);
+
+ /* Create file in fs */
+ dentry = chan->cb->create_buf_file(tmpname, chan->parent, S_IRUSR,
+ buf);
+ if (!dentry)
+ goto free_buf;
+
+ buf->dentry = dentry;
+
+ goto free_name;
+
+free_buf:
+ relay_destroy_buf(buf);
+ buf = NULL;
+free_name:
+ kfree(tmpname);
+end:
+ return buf;
+}
+
+/**
+ * relay_close_buf - close a channel buffer
+ * @buf: channel buffer
+ *
+ * Marks the buffer finalized and restores the default callbacks.
+ * The channel buffer and channel buffer data structure are then freed
+ * automatically when the last reference is given up.
+ */
+static void relay_close_buf(struct rchan_buf *buf)
+{
+ del_timer_sync(&buf->timer);
+ kref_put(&buf->kref, relay_remove_buf);
+}
+
+static void setup_callbacks(struct rchan *chan,
+ struct rchan_callbacks *cb)
+{
+ if (!cb) {
+ chan->cb = &default_channel_callbacks;
+ return;
+ }
+
+ if (!cb->create_buf_file)
+ cb->create_buf_file = create_buf_file_default_callback;
+ if (!cb->remove_buf_file)
+ cb->remove_buf_file = remove_buf_file_default_callback;
+ chan->cb = cb;
+}
+
+/**
+ * relay_hotcpu_callback - CPU hotplug callback
+ * @nb: notifier block
+ * @action: hotplug action to take
+ * @hcpu: CPU number
+ *
+ * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
+ */
+static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb,
+ unsigned long action,
+ void *hcpu)
+{
+ unsigned int hotcpu = (unsigned long)hcpu;
+ struct rchan *chan;
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ mutex_lock(&relay_channels_mutex);
+ list_for_each_entry(chan, &relay_channels, list) {
+ if (chan->buf[hotcpu])
+ continue;
+ chan->buf[hotcpu] = relay_open_buf(chan, hotcpu);
+ if (!chan->buf[hotcpu]) {
+ printk(KERN_ERR
+ "relay_hotcpu_callback: cpu %d buffer "
+ "creation failed\n", hotcpu);
+ mutex_unlock(&relay_channels_mutex);
+ return NOTIFY_BAD;
+ }
+ }
+ mutex_unlock(&relay_channels_mutex);
+ break;
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ /* No need to flush the cpu : will be flushed upon
+ * final relay_flush() call. */
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+/**
+ * ltt_relay_open - create a new relay channel
+ * @base_filename: base name of files to create
+ * @parent: dentry of parent directory, %NULL for root directory
+ * @subbuf_size: size of sub-buffers
+ * @n_subbufs: number of sub-buffers
+ * @cb: client callback functions
+ * @private_data: user-defined data
+ *
+ * Returns channel pointer if successful, %NULL otherwise.
+ *
+ * Creates a channel buffer for each cpu using the sizes and
+ * attributes specified. The created channel buffer files
+ * will be named base_filename0...base_filenameN-1. File
+ * permissions will be %S_IRUSR.
+ */
+struct rchan *ltt_relay_open(const char *base_filename,
+ struct dentry *parent,
+ size_t subbuf_size,
+ size_t n_subbufs,
+ struct rchan_callbacks *cb,
+ void *private_data)
+{
+ unsigned int i;
+ struct rchan *chan;
+ if (!base_filename)
+ return NULL;
+
+ if (!(subbuf_size && n_subbufs))
+ return NULL;
+
+ chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
+ if (!chan)
+ return NULL;
+
+ chan->version = LTT_RELAY_CHANNEL_VERSION;
+ chan->n_subbufs = n_subbufs;
+ chan->subbuf_size = subbuf_size;
+ chan->subbuf_size_order = get_count_order(subbuf_size);
+ chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
+ chan->parent = parent;
+ chan->private_data = private_data;
+ strlcpy(chan->base_filename, base_filename, NAME_MAX);
+ setup_callbacks(chan, cb);
+ kref_init(&chan->kref);
+
+ mutex_lock(&relay_channels_mutex);
+ for_each_online_cpu(i) {
+ chan->buf[i] = relay_open_buf(chan, i);
+ if (!chan->buf[i])
+ goto free_bufs;
+ }
+ list_add(&chan->list, &relay_channels);
+ mutex_unlock(&relay_channels_mutex);
+
+ return chan;
+
+free_bufs:
+ for_each_possible_cpu(i) {
+ if (!chan->buf[i])
+ break;
+ relay_close_buf(chan->buf[i]);
+ }
+
+ kref_put(&chan->kref, relay_destroy_channel);
+ mutex_unlock(&relay_channels_mutex);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(ltt_relay_open);
+
+/**
+ * ltt_relay_close - close the channel
+ * @chan: the channel
+ *
+ * Closes all channel buffers and frees the channel.
+ */
+void ltt_relay_close(struct rchan *chan)
+{
+ unsigned int i;
+
+ if (!chan)
+ return;
+
+ mutex_lock(&relay_channels_mutex);
+ for_each_possible_cpu(i)
+ if (chan->buf[i])
+ relay_close_buf(chan->buf[i]);
+
+ list_del(&chan->list);
+ kref_put(&chan->kref, relay_destroy_channel);
+ mutex_unlock(&relay_channels_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_relay_close);
+
+/*
+ * Start iteration at the previous element. Skip the real list head.
+ */
+struct buf_page *ltt_relay_find_prev_page(struct rchan_buf *buf,
+ struct buf_page *page, size_t offset, ssize_t diff_offset)
+{
+ struct buf_page *iter;
+ size_t orig_iter_off;
+ unsigned int i = 0;
+
+ orig_iter_off = page->offset;
+ list_for_each_entry_reverse(iter, &page->list, list) {
+ /*
+ * Skip the real list head.
+ */
+ if (&iter->list == &buf->pages)
+ continue;
+ i++;
+ if (offset >= iter->offset
+ && offset < iter->offset + PAGE_SIZE) {
+#ifdef CONFIG_LTT_RELAY_CHECK_RANDOM_ACCESS
+ if (i > 1) {
+ printk(KERN_WARNING
+ "Backward random access detected in "
+ "ltt_relay. Iterations %u, "
+ "offset %zu, orig iter->off %zu, "
+ "iter->off %zu diff_offset %zd.\n", i,
+ offset, orig_iter_off, iter->offset,
+ diff_offset);
+ WARN_ON(1);
+ }
+#endif
+ return iter;
+ }
+ }
+ WARN_ON(1);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(ltt_relay_find_prev_page);
+
+/*
+ * Start iteration at the next element. Skip the real list head.
+ */
+struct buf_page *ltt_relay_find_next_page(struct rchan_buf *buf,
+ struct buf_page *page, size_t offset, ssize_t diff_offset)
+{
+ struct buf_page *iter;
+ unsigned int i = 0;
+ size_t orig_iter_off;
+
+ orig_iter_off = page->offset;
+ list_for_each_entry(iter, &page->list, list) {
+ /*
+ * Skip the real list head.
+ */
+ if (&iter->list == &buf->pages)
+ continue;
+ i++;
+ if (offset >= iter->offset
+ && offset < iter->offset + PAGE_SIZE) {
+#ifdef CONFIG_LTT_RELAY_CHECK_RANDOM_ACCESS
+ if (i > 1) {
+ printk(KERN_WARNING
+ "Forward random access detected in "
+ "ltt_relay. Iterations %u, "
+ "offset %zu, orig iter->off %zu, "
+ "iter->off %zu diff_offset %zd.\n", i,
+ offset, orig_iter_off, iter->offset,
+ diff_offset);
+ WARN_ON(1);
+ }
+#endif
+ return iter;
+ }
+ }
+ WARN_ON(1);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(ltt_relay_find_next_page);
+
+/**
+ * ltt_relay_write - write data to a ltt_relay buffer.
+ * @buf : buffer
+ * @offset : offset within the buffer
+ * @src : source address
+ * @len : length to write
+ * @page : cached buffer page
+ * @pagecpy : page size copied so far
+ */
+void _ltt_relay_write(struct rchan_buf *buf, size_t offset,
+ const void *src, size_t len, struct buf_page *page, ssize_t pagecpy)
+{
+ do {
+ len -= pagecpy;
+ src += pagecpy;
+ offset += pagecpy;
+ /*
+ * Underlying layer should never ask for writes across
+ * subbuffers.
+ */
+ WARN_ON(offset >= buf->chan->alloc_size);
+
+ page = ltt_relay_cache_page(buf, &buf->wpage, page, offset);
+ pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+ ltt_relay_do_copy(page_address(page->page)
+ + (offset & ~PAGE_MASK), src, pagecpy);
+ } while (unlikely(len != pagecpy));
+}
+EXPORT_SYMBOL_GPL(_ltt_relay_write);
+
+/**
+ * ltt_relay_read - read data from ltt_relay_buffer.
+ * @buf : buffer
+ * @offset : offset within the buffer
+ * @dest : destination address
+ * @len : length to write
+ */
+int ltt_relay_read(struct rchan_buf *buf, size_t offset,
+ void *dest, size_t len)
+{
+ struct buf_page *page;
+ ssize_t pagecpy, orig_len;
+
+ orig_len = len;
+ offset &= buf->chan->alloc_size - 1;
+ page = buf->rpage;
+ if (unlikely(!len))
+ return 0;
+ for (;;) {
+ page = ltt_relay_cache_page(buf, &buf->rpage, page, offset);
+ pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+ memcpy(dest, page_address(page->page) + (offset & ~PAGE_MASK),
+ pagecpy);
+ len -= pagecpy;
+ if (likely(!len))
+ break;
+ dest += pagecpy;
+ offset += pagecpy;
+ /*
+ * Underlying layer should never ask for reads across
+ * subbuffers.
+ */
+ WARN_ON(offset >= buf->chan->alloc_size);
+ }
+ return orig_len;
+}
+EXPORT_SYMBOL_GPL(ltt_relay_read);
+
+/**
+ * ltt_relay_read_get_page - Get a whole page to read from
+ * @buf : buffer
+ * @offset : offset within the buffer
+ */
+struct buf_page *ltt_relay_read_get_page(struct rchan_buf *buf, size_t offset)
+{
+ struct buf_page *page;
+
+ offset &= buf->chan->alloc_size - 1;
+ page = buf->rpage;
+ page = ltt_relay_cache_page(buf, &buf->rpage, page, offset);
+ return page;
+}
+EXPORT_SYMBOL_GPL(ltt_relay_read_get_page);
+
+/**
+ * ltt_relay_offset_address - get address of a location within the buffer
+ * @buf : buffer
+ * @offset : offset within the buffer.
+ *
+ * Return the address where a given offset is located.
+ * Should be used to get the current subbuffer header pointer. Given we know
+ * it's never on a page boundary, it's safe to write directly to this address,
+ * as long as the write is never bigger than a page size.
+ */
+void *ltt_relay_offset_address(struct rchan_buf *buf, size_t offset)
+{
+ struct buf_page *page;
+ unsigned int odd;
+
+ offset &= buf->chan->alloc_size - 1;
+ odd = !!(offset & buf->chan->subbuf_size);
+ page = buf->hpage[odd];
+ if (offset < page->offset || offset >= page->offset + PAGE_SIZE)
+ buf->hpage[odd] = page = buf->wpage;
+ page = ltt_relay_cache_page(buf, &buf->hpage[odd], page, offset);
+ return page_address(page->page) + (offset & ~PAGE_MASK);
+}
+EXPORT_SYMBOL_GPL(ltt_relay_offset_address);
+
+/**
+ * relay_file_open - open file op for relay files
+ * @inode: the inode
+ * @filp: the file
+ *
+ * Increments the channel buffer refcount.
+ */
+static int relay_file_open(struct inode *inode, struct file *filp)
+{
+ struct rchan_buf *buf = inode->i_private;
+ kref_get(&buf->kref);
+ filp->private_data = buf;
+
+ return nonseekable_open(inode, filp);
+}
+
+/**
+ * relay_file_release - release file op for relay files
+ * @inode: the inode
+ * @filp: the file
+ *
+ * Decrements the channel refcount, as the filesystem is
+ * no longer using it.
+ */
+static int relay_file_release(struct inode *inode, struct file *filp)
+{
+ struct rchan_buf *buf = filp->private_data;
+ kref_put(&buf->kref, relay_remove_buf);
+
+ return 0;
+}
+
+const struct file_operations ltt_relay_file_operations = {
+ .open = relay_file_open,
+ .release = relay_file_release,
+};
+EXPORT_SYMBOL_GPL(ltt_relay_file_operations);
+
+static __init int relay_init(void)
+{
+ hotcpu_notifier(relay_hotcpu_callback, 5);
+ return 0;
+}
+
+module_init(relay_init);
--- /dev/null
+/*
+ * ltt/ltt-relay.c
+ *
+ * (C) Copyright 2005-2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * LTTng lockless buffer space management (reader/writer).
+ *
+ * Author:
+ * Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * Inspired from LTT :
+ * Karim Yaghmour (karim@opersys.com)
+ * Tom Zanussi (zanussi@us.ibm.com)
+ * Bob Wisniewski (bob@watson.ibm.com)
+ * And from K42 :
+ * Bob Wisniewski (bob@watson.ibm.com)
+ *
+ * Changelog:
+ * 08/10/08, Cleanup.
+ * 19/10/05, Complete lockless mechanism.
+ * 27/05/05, Modular redesign and rewrite.
+ *
+ * Userspace reader semantic :
+ * while (poll fd != POLLHUP) {
+ * - ioctl RELAY_GET_SUBBUF_SIZE
+ * while (1) {
+ * - ioctl GET_SUBBUF
+ * - splice 1 subbuffer worth of data to a pipe
+ * - splice the data from pipe to disk/network
+ * - ioctl PUT_SUBBUF, check error value
+ * if err val < 0, previous subbuffer was corrupted.
+ * }
+ * }
+ */
+
+#include <linux/time.h>
+#include <linux/ltt-tracer.h>
+#include <linux/ltt-relay.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/bitops.h>
+#include <linux/fs.h>
+#include <linux/smp_lock.h>
+#include <linux/debugfs.h>
+#include <linux/stat.h>
+#include <linux/cpu.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/splice.h>
+#include <asm/atomic.h>
+#include <asm/local.h>
+
+#if 0
+#define printk_dbg(fmt, args...) printk(fmt, args)
+#else
+#define printk_dbg(fmt, args...)
+#endif
+
+/* LTTng lockless logging buffer info */
+struct ltt_channel_buf_struct {
+ /* First 32 bytes cache-hot cacheline */
+ local_t offset; /* Current offset in the buffer */
+ local_t *commit_count; /* Commit count per sub-buffer */
+ atomic_long_t consumed; /*
+ * Current offset in the buffer
+ * standard atomic access (shared)
+ */
+ unsigned long last_tsc; /*
+ * Last timestamp written in the buffer.
+ */
+ /* End of first 32 bytes cacheline */
+ atomic_long_t active_readers; /*
+ * Active readers count
+ * standard atomic access (shared)
+ */
+ local_t events_lost;
+ local_t corrupted_subbuffers;
+ spinlock_t full_lock; /*
+ * buffer full condition spinlock, only
+ * for userspace tracing blocking mode
+ * synchronization with reader.
+ */
+ wait_queue_head_t write_wait; /*
+ * Wait queue for blocking user space
+ * writers
+ */
+ atomic_t wakeup_readers; /* Boolean : wakeup readers waiting ? */
+} ____cacheline_aligned;
+
+/*
+ * Last TSC comparison functions. Check if the current TSC overflows
+ * LTT_TSC_BITS bits from the last TSC read. Reads and writes last_tsc
+ * atomically.
+ */
+
+#if (BITS_PER_LONG == 32)
+static inline void save_last_tsc(struct ltt_channel_buf_struct *ltt_buf,
+ u64 tsc)
+{
+ ltt_buf->last_tsc = (unsigned long)(tsc >> LTT_TSC_BITS);
+}
+
+static inline int last_tsc_overflow(struct ltt_channel_buf_struct *ltt_buf,
+ u64 tsc)
+{
+ unsigned long tsc_shifted = (unsigned long)(tsc >> LTT_TSC_BITS);
+
+ if (unlikely((tsc_shifted - ltt_buf->last_tsc)))
+ return 1;
+ else
+ return 0;
+}
+#else
+static inline void save_last_tsc(struct ltt_channel_buf_struct *ltt_buf,
+ u64 tsc)
+{
+ ltt_buf->last_tsc = (unsigned long)tsc;
+}
+
+static inline int last_tsc_overflow(struct ltt_channel_buf_struct *ltt_buf,
+ u64 tsc)
+{
+ if (unlikely((tsc - ltt_buf->last_tsc) >> LTT_TSC_BITS))
+ return 1;
+ else
+ return 0;
+}
+#endif
+
+static struct file_operations ltt_file_operations;
+
+/*
+ * A switch is done during tracing or as a final flush after tracing (so it
+ * won't write in the new sub-buffer).
+ */
+enum force_switch_mode { FORCE_ACTIVE, FORCE_FLUSH };
+
+static int ltt_relay_create_buffer(struct ltt_trace_struct *trace,
+ struct ltt_channel_struct *ltt_chan,
+ struct rchan_buf *buf,
+ unsigned int cpu,
+ unsigned int n_subbufs);
+
+static void ltt_relay_destroy_buffer(struct ltt_channel_struct *ltt_chan,
+ unsigned int cpu);
+
+static void ltt_force_switch(struct rchan_buf *buf,
+ enum force_switch_mode mode);
+
+/*
+ * Trace callbacks
+ */
+static void ltt_buffer_begin_callback(struct rchan_buf *buf,
+ u64 tsc, unsigned int subbuf_idx)
+{
+ struct ltt_channel_struct *channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_subbuffer_header *header =
+ (struct ltt_subbuffer_header *)
+ ltt_relay_offset_address(buf,
+ subbuf_idx * buf->chan->subbuf_size);
+
+ header->cycle_count_begin = tsc;
+ header->lost_size = 0xFFFFFFFF; /* for debugging */
+ header->buf_size = buf->chan->subbuf_size;
+ ltt_write_trace_header(channel->trace, header);
+}
+
+/*
+ * offset is assumed to never be 0 here : never deliver a completely empty
+ * subbuffer. The lost size is between 0 and subbuf_size-1.
+ */
+static notrace void ltt_buffer_end_callback(struct rchan_buf *buf,
+ u64 tsc, unsigned int offset, unsigned int subbuf_idx)
+{
+ struct ltt_channel_struct *channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(channel->buf, buf->cpu);
+ struct ltt_subbuffer_header *header =
+ (struct ltt_subbuffer_header *)
+ ltt_relay_offset_address(buf,
+ subbuf_idx * buf->chan->subbuf_size);
+
+ header->lost_size = SUBBUF_OFFSET((buf->chan->subbuf_size - offset),
+ buf->chan);
+ header->cycle_count_end = tsc;
+ header->events_lost = local_read(<t_buf->events_lost);
+ header->subbuf_corrupt = local_read(<t_buf->corrupted_subbuffers);
+}
+
+static notrace void ltt_deliver(struct rchan_buf *buf, unsigned int subbuf_idx,
+ void *subbuf)
+{
+ struct ltt_channel_struct *channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(channel->buf, buf->cpu);
+
+ atomic_set(<t_buf->wakeup_readers, 1);
+}
+
+static struct dentry *ltt_create_buf_file_callback(const char *filename,
+ struct dentry *parent, int mode,
+ struct rchan_buf *buf)
+{
+ struct ltt_channel_struct *ltt_chan;
+ int err;
+ struct dentry *dentry;
+
+ ltt_chan = buf->chan->private_data;
+ err = ltt_relay_create_buffer(ltt_chan->trace, ltt_chan,
+ buf, buf->cpu,
+ buf->chan->n_subbufs);
+ if (err)
+ return ERR_PTR(err);
+
+ dentry = debugfs_create_file(filename, mode, parent, buf,
+ <t_file_operations);
+ if (!dentry)
+ goto error;
+ return dentry;
+error:
+ ltt_relay_destroy_buffer(ltt_chan, buf->cpu);
+ return NULL;
+}
+
+static int ltt_remove_buf_file_callback(struct dentry *dentry)
+{
+ struct rchan_buf *buf = dentry->d_inode->i_private;
+ struct ltt_channel_struct *ltt_chan = buf->chan->private_data;
+
+ debugfs_remove(dentry);
+ ltt_relay_destroy_buffer(ltt_chan, buf->cpu);
+
+ return 0;
+}
+
+/*
+ * Wake writers :
+ *
+ * This must be done after the trace is removed from the RCU list so that there
+ * are no stalled writers.
+ */
+static void ltt_relay_wake_writers(struct ltt_channel_buf_struct *ltt_buf)
+{
+
+ if (waitqueue_active(<t_buf->write_wait))
+ wake_up_interruptible(<t_buf->write_wait);
+}
+
+/*
+ * This function should not be called from NMI interrupt context
+ */
+static notrace void ltt_buf_unfull(struct rchan_buf *buf,
+ unsigned int subbuf_idx,
+ long offset)
+{
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+
+ ltt_relay_wake_writers(ltt_buf);
+}
+
+/**
+ * ltt_open - open file op for ltt files
+ * @inode: opened inode
+ * @file: opened file
+ *
+ * Open implementation. Makes sure only one open instance of a buffer is
+ * done at a given moment.
+ */
+static int ltt_open(struct inode *inode, struct file *file)
+{
+ struct rchan_buf *buf = inode->i_private;
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+
+ if (!atomic_long_add_unless(<t_buf->active_readers, 1, 1))
+ return -EBUSY;
+ return ltt_relay_file_operations.open(inode, file);
+}
+
+/**
+ * ltt_release - release file op for ltt files
+ * @inode: opened inode
+ * @file: opened file
+ *
+ * Release implementation.
+ */
+static int ltt_release(struct inode *inode, struct file *file)
+{
+ struct rchan_buf *buf = inode->i_private;
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ int ret;
+
+ WARN_ON(atomic_long_read(<t_buf->active_readers) != 1);
+ atomic_long_dec(<t_buf->active_readers);
+ ret = ltt_relay_file_operations.release(inode, file);
+ WARN_ON(ret);
+ return ret;
+}
+
+/**
+ * ltt_poll - file op for ltt files
+ * @filp: the file
+ * @wait: poll table
+ *
+ * Poll implementation.
+ */
+static unsigned int ltt_poll(struct file *filp, poll_table *wait)
+{
+ unsigned int mask = 0;
+ struct inode *inode = filp->f_dentry->d_inode;
+ struct rchan_buf *buf = inode->i_private;
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+
+ if (filp->f_mode & FMODE_READ) {
+ poll_wait_set_exclusive(wait);
+ poll_wait(filp, &buf->read_wait, wait);
+
+ WARN_ON(atomic_long_read(<t_buf->active_readers) != 1);
+ if (SUBBUF_TRUNC(local_read(<t_buf->offset),
+ buf->chan)
+ - SUBBUF_TRUNC(atomic_long_read(<t_buf->consumed),
+ buf->chan)
+ == 0) {
+ if (buf->finalized)
+ return POLLHUP;
+ else
+ return 0;
+ } else {
+ struct rchan *rchan =
+ ltt_channel->trans_channel_data;
+ if (SUBBUF_TRUNC(local_read(<t_buf->offset),
+ buf->chan)
+ - SUBBUF_TRUNC(atomic_long_read(
+ <t_buf->consumed),
+ buf->chan)
+ >= rchan->alloc_size)
+ return POLLPRI | POLLRDBAND;
+ else
+ return POLLIN | POLLRDNORM;
+ }
+ }
+ return mask;
+}
+
+static int ltt_do_get_subbuf(struct rchan_buf *buf, struct ltt_channel_buf_struct *ltt_buf, long *pconsumed_old)
+{
+ long consumed_old, consumed_idx, commit_count, write_offset;
+ consumed_old = atomic_long_read(<t_buf->consumed);
+ consumed_idx = SUBBUF_INDEX(consumed_old, buf->chan);
+ commit_count = local_read(<t_buf->commit_count[consumed_idx]);
+ /*
+ * Make sure we read the commit count before reading the buffer
+ * data and the write offset. Correct consumed offset ordering
+ * wrt commit count is insured by the use of cmpxchg to update
+ * the consumed offset.
+ */
+ smp_rmb();
+ write_offset = local_read(<t_buf->offset);
+ /*
+ * Check that the subbuffer we are trying to consume has been
+ * already fully committed.
+ */
+ if (((commit_count - buf->chan->subbuf_size)
+ & ltt_channel->commit_count_mask)
+ - (BUFFER_TRUNC(consumed_old, buf->chan)
+ >> ltt_channel->n_subbufs_order)
+ != 0) {
+ return -EAGAIN;
+ }
+ /*
+ * Check that we are not about to read the same subbuffer in
+ * which the writer head is.
+ */
+ if ((SUBBUF_TRUNC(write_offset, buf->chan)
+ - SUBBUF_TRUNC(consumed_old, buf->chan))
+ == 0) {
+ return -EAGAIN;
+ }
+
+ *pconsumed_old = consumed_old;
+ return 0;
+}
+
+static int ltt_do_put_subbuf(struct rchan_buf *buf, struct ltt_channel_buf_struct *ltt_buf, u32 uconsumed_old)
+{
+ long consumed_new, consumed_old;
+
+ consumed_old = atomic_long_read(<t_buf->consumed);
+ consumed_old = consumed_old & (~0xFFFFFFFFL);
+ consumed_old = consumed_old | uconsumed_old;
+ consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
+
+ spin_lock(<t_buf->full_lock);
+ if (atomic_long_cmpxchg(<t_buf->consumed, consumed_old,
+ consumed_new)
+ != consumed_old) {
+ /* We have been pushed by the writer : the last
+ * buffer read _is_ corrupted! It can also
+ * happen if this is a buffer we never got. */
+ spin_unlock(<t_buf->full_lock);
+ return -EIO;
+ } else {
+ /* tell the client that buffer is now unfull */
+ int index;
+ long data;
+ index = SUBBUF_INDEX(consumed_old, buf->chan);
+ data = BUFFER_OFFSET(consumed_old, buf->chan);
+ ltt_buf_unfull(buf, index, data);
+ spin_unlock(<t_buf->full_lock);
+ }
+ return 0;
+}
+
+/**
+ * ltt_ioctl - control on the debugfs file
+ *
+ * @inode: the inode
+ * @filp: the file
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This ioctl implements three commands necessary for a minimal
+ * producer/consumer implementation :
+ * RELAY_GET_SUBBUF
+ * Get the next sub buffer that can be read. It never blocks.
+ * RELAY_PUT_SUBBUF
+ * Release the currently read sub-buffer. Parameter is the last
+ * put subbuffer (returned by GET_SUBBUF).
+ * RELAY_GET_N_BUBBUFS
+ * returns the number of sub buffers in the per cpu channel.
+ * RELAY_GET_SUBBUF_SIZE
+ * returns the size of the sub buffers.
+ */
+static int ltt_ioctl(struct inode *inode, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+ struct rchan_buf *buf = inode->i_private;
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ u32 __user *argp = (u32 __user *)arg;
+
+ WARN_ON(atomic_long_read(<t_buf->active_readers) != 1);
+ switch (cmd) {
+ case RELAY_GET_SUBBUF:
+ {
+ int ret;
+ ret = ltt_do_get_subbuf(buf, ltt_buf, &consumed_old);
+ if(ret < 0)
+ return ret;
+ return put_user((u32)consumed_old, argp);
+ }
+ case RELAY_PUT_SUBBUF:
+ {
+ int ret;
+ u32 uconsumed_old;
+ ret = get_user(uconsumed_old, argp);
+ if (ret)
+ return ret; /* will return -EFAULT */
+ return ltt_do_put_subbuf(buf, ltt_buf, uconsumed_old);
+ }
+ case RELAY_GET_N_SUBBUFS:
+ return put_user((u32)buf->chan->n_subbufs, argp);
+ break;
+ case RELAY_GET_SUBBUF_SIZE:
+ return put_user((u32)buf->chan->subbuf_size, argp);
+ break;
+ default:
+ return -ENOIOCTLCMD;
+ }
+ return 0;
+}
+
+#ifdef CONFIG_COMPAT
+static long ltt_compat_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ long ret = -ENOIOCTLCMD;
+
+ lock_kernel();
+ ret = ltt_ioctl(file->f_dentry->d_inode, file, cmd, arg);
+ unlock_kernel();
+
+ return ret;
+}
+#endif
+
+static void ltt_relay_pipe_buf_release(struct pipe_inode_info *pipe,
+ struct pipe_buffer *pbuf)
+{
+}
+
+static struct pipe_buf_operations ltt_relay_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = ltt_relay_pipe_buf_release,
+ .steal = generic_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
+
+static void ltt_relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
+{
+}
+
+/*
+ * subbuf_splice_actor - splice up to one subbuf's worth of data
+ */
+static int subbuf_splice_actor(struct file *in,
+ loff_t *ppos,
+ struct pipe_inode_info *pipe,
+ size_t len,
+ unsigned int flags)
+{
+ struct rchan_buf *buf = in->private_data;
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ unsigned int poff, subbuf_pages, nr_pages;
+ struct page *pages[PIPE_BUFFERS];
+ struct partial_page partial[PIPE_BUFFERS];
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .nr_pages = 0,
+ .partial = partial,
+ .flags = flags,
+ .ops = <t_relay_pipe_buf_ops,
+ .spd_release = ltt_relay_page_release,
+ };
+ long consumed_old, consumed_idx, roffset;
+ unsigned long bytes_avail;
+
+ /*
+ * Check that a GET_SUBBUF ioctl has been done before.
+ */
+ WARN_ON(atomic_long_read(<t_buf->active_readers) != 1);
+ consumed_old = atomic_long_read(<t_buf->consumed);
+ consumed_old += *ppos;
+ consumed_idx = SUBBUF_INDEX(consumed_old, buf->chan);
+
+ /*
+ * Adjust read len, if longer than what is available
+ */
+ bytes_avail = SUBBUF_TRUNC(local_read(<t_buf->offset), buf->chan)
+ - consumed_old;
+ WARN_ON(bytes_avail > buf->chan->alloc_size);
+ len = min_t(size_t, len, bytes_avail);
+ subbuf_pages = bytes_avail >> PAGE_SHIFT;
+ nr_pages = min_t(unsigned int, subbuf_pages, PIPE_BUFFERS);
+ roffset = consumed_old & PAGE_MASK;
+ poff = consumed_old & ~PAGE_MASK;
+ printk_dbg(KERN_DEBUG "SPLICE actor len %zu pos %zd write_pos %ld\n",
+ len, (ssize_t)*ppos, local_read(<t_buf->offset));
+
+ for (; spd.nr_pages < nr_pages; spd.nr_pages++) {
+ unsigned int this_len;
+ struct buf_page *page;
+
+ if (!len)
+ break;
+ printk_dbg(KERN_DEBUG "SPLICE actor loop len %zu roffset %ld\n",
+ len, roffset);
+
+ this_len = PAGE_SIZE - poff;
+ page = ltt_relay_read_get_page(buf, roffset);
+ spd.pages[spd.nr_pages] = page->page;
+ spd.partial[spd.nr_pages].offset = poff;
+ spd.partial[spd.nr_pages].len = this_len;
+
+ poff = 0;
+ roffset += PAGE_SIZE;
+ len -= this_len;
+ }
+
+ if (!spd.nr_pages)
+ return 0;
+
+ return splice_to_pipe(pipe, &spd);
+}
+
+static ssize_t ltt_relay_file_splice_read(struct file *in,
+ loff_t *ppos,
+ struct pipe_inode_info *pipe,
+ size_t len,
+ unsigned int flags)
+{
+ ssize_t spliced;
+ int ret;
+
+ ret = 0;
+ spliced = 0;
+
+ printk_dbg(KERN_DEBUG "SPLICE read len %zu pos %zd\n",
+ len, (ssize_t)*ppos);
+ while (len && !spliced) {
+ ret = subbuf_splice_actor(in, ppos, pipe, len, flags);
+ printk_dbg(KERN_DEBUG "SPLICE read loop ret %d\n", ret);
+ if (ret < 0)
+ break;
+ else if (!ret) {
+ if (flags & SPLICE_F_NONBLOCK)
+ ret = -EAGAIN;
+ break;
+ }
+
+ *ppos += ret;
+ if (ret > len)
+ len = 0;
+ else
+ len -= ret;
+ spliced += ret;
+ }
+
+ if (spliced)
+ return spliced;
+
+ return ret;
+}
+
+static void ltt_relay_print_subbuffer_errors(
+ struct ltt_channel_struct *ltt_chan,
+ long cons_off, unsigned int cpu)
+{
+ struct rchan *rchan = ltt_chan->trans_channel_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_chan->buf, cpu);
+ long cons_idx, commit_count, write_offset;
+
+ cons_idx = SUBBUF_INDEX(cons_off, rchan);
+ commit_count = local_read(<t_buf->commit_count[cons_idx]);
+ /*
+ * No need to order commit_count and write_offset reads because we
+ * execute after trace is stopped when there are no readers left.
+ */
+ write_offset = local_read(<t_buf->offset);
+ printk(KERN_WARNING
+ "LTT : unread channel %s offset is %ld "
+ "and cons_off : %ld (cpu %u)\n",
+ ltt_chan->channel_name, write_offset, cons_off, cpu);
+ /* Check each sub-buffer for non filled commit count */
+ if (((commit_count - rchan->subbuf_size) & ltt_chan->commit_count_mask)
+ - (BUFFER_TRUNC(cons_off, rchan) >> ltt_chan->n_subbufs_order)
+ != 0)
+ printk(KERN_ALERT
+ "LTT : %s : subbuffer %lu has non filled "
+ "commit count %lu.\n",
+ ltt_chan->channel_name, cons_idx, commit_count);
+ printk(KERN_ALERT "LTT : %s : commit count : %lu, subbuf size %zd\n",
+ ltt_chan->channel_name, commit_count,
+ rchan->subbuf_size);
+}
+
+static void ltt_relay_print_errors(struct ltt_trace_struct *trace,
+ struct ltt_channel_struct *ltt_chan, int cpu)
+{
+ struct rchan *rchan = ltt_chan->trans_channel_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_chan->buf, cpu);
+ long cons_off;
+
+ for (cons_off = atomic_long_read(<t_buf->consumed);
+ (SUBBUF_TRUNC(local_read(<t_buf->offset),
+ rchan)
+ - cons_off) > 0;
+ cons_off = SUBBUF_ALIGN(cons_off, rchan))
+ ltt_relay_print_subbuffer_errors(ltt_chan, cons_off, cpu);
+}
+
+static void ltt_relay_print_buffer_errors(struct ltt_channel_struct *ltt_chan,
+ unsigned int cpu)
+{
+ struct ltt_trace_struct *trace = ltt_chan->trace;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_chan->buf, cpu);
+
+ if (local_read(<t_buf->events_lost))
+ printk(KERN_ALERT
+ "LTT : %s : %ld events lost "
+ "in %s channel (cpu %u).\n",
+ ltt_chan->channel_name,
+ local_read(<t_buf->events_lost),
+ ltt_chan->channel_name, cpu);
+ if (local_read(<t_buf->corrupted_subbuffers))
+ printk(KERN_ALERT
+ "LTT : %s : %ld corrupted subbuffers "
+ "in %s channel (cpu %u).\n",
+ ltt_chan->channel_name,
+ local_read(<t_buf->corrupted_subbuffers),
+ ltt_chan->channel_name, cpu);
+
+ ltt_relay_print_errors(trace, ltt_chan, cpu);
+}
+
+static void ltt_relay_remove_dirs(struct ltt_trace_struct *trace)
+{
+ debugfs_remove(trace->dentry.trace_root);
+}
+
+static void ltt_relay_release_channel(struct kref *kref)
+{
+ struct ltt_channel_struct *ltt_chan = container_of(kref,
+ struct ltt_channel_struct, kref);
+ percpu_free(ltt_chan->buf);
+}
+
+/*
+ * Create ltt buffer.
+ */
+static int ltt_relay_create_buffer(struct ltt_trace_struct *trace,
+ struct ltt_channel_struct *ltt_chan, struct rchan_buf *buf,
+ unsigned int cpu, unsigned int n_subbufs)
+{
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_chan->buf, cpu);
+ unsigned int j;
+
+ ltt_buf->commit_count =
+ kzalloc_node(sizeof(ltt_buf->commit_count) * n_subbufs,
+ GFP_KERNEL, cpu_to_node(cpu));
+ if (!ltt_buf->commit_count)
+ return -ENOMEM;
+ kref_get(&trace->kref);
+ kref_get(&trace->ltt_transport_kref);
+ kref_get(<t_chan->kref);
+ local_set(<t_buf->offset, ltt_subbuffer_header_size());
+ atomic_long_set(<t_buf->consumed, 0);
+ atomic_long_set(<t_buf->active_readers, 0);
+ for (j = 0; j < n_subbufs; j++)
+ local_set(<t_buf->commit_count[j], 0);
+ init_waitqueue_head(<t_buf->write_wait);
+ atomic_set(<t_buf->wakeup_readers, 0);
+ spin_lock_init(<t_buf->full_lock);
+
+ ltt_buffer_begin_callback(buf, trace->start_tsc, 0);
+ /* atomic_add made on local variable on data that belongs to
+ * various CPUs : ok because tracing not started (for this cpu). */
+ local_add(ltt_subbuffer_header_size(), <t_buf->commit_count[0]);
+
+ local_set(<t_buf->events_lost, 0);
+ local_set(<t_buf->corrupted_subbuffers, 0);
+
+ return 0;
+}
+
+static void ltt_relay_destroy_buffer(struct ltt_channel_struct *ltt_chan,
+ unsigned int cpu)
+{
+ struct ltt_trace_struct *trace = ltt_chan->trace;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_chan->buf, cpu);
+
+ kref_put(<t_chan->trace->ltt_transport_kref,
+ ltt_release_transport);
+ ltt_relay_print_buffer_errors(ltt_chan, cpu);
+ kfree(ltt_buf->commit_count);
+ ltt_buf->commit_count = NULL;
+ kref_put(<t_chan->kref, ltt_relay_release_channel);
+ kref_put(&trace->kref, ltt_release_trace);
+ wake_up_interruptible(&trace->kref_wq);
+}
+
+/*
+ * Create channel.
+ */
+static int ltt_relay_create_channel(const char *trace_name,
+ struct ltt_trace_struct *trace, struct dentry *dir,
+ const char *channel_name, struct ltt_channel_struct *ltt_chan,
+ unsigned int subbuf_size, unsigned int n_subbufs,
+ int overwrite)
+{
+ char *tmpname;
+ unsigned int tmpname_len;
+ int err = 0;
+
+ tmpname = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!tmpname)
+ return EPERM;
+ if (overwrite) {
+ strncpy(tmpname, LTT_FLIGHT_PREFIX, PATH_MAX-1);
+ strncat(tmpname, channel_name,
+ PATH_MAX-1-sizeof(LTT_FLIGHT_PREFIX));
+ } else {
+ strncpy(tmpname, channel_name, PATH_MAX-1);
+ }
+ strncat(tmpname, "_", PATH_MAX-1-strlen(tmpname));
+
+ kref_init(<t_chan->kref);
+
+ ltt_chan->trace = trace;
+ ltt_chan->buffer_begin = ltt_buffer_begin_callback;
+ ltt_chan->buffer_end = ltt_buffer_end_callback;
+ ltt_chan->overwrite = overwrite;
+ ltt_chan->n_subbufs_order = get_count_order(n_subbufs);
+ ltt_chan->commit_count_mask = (~0UL >> ltt_chan->n_subbufs_order);
+ ltt_chan->buf = percpu_alloc_mask(sizeof(struct ltt_channel_buf_struct),
+ GFP_KERNEL, cpu_possible_map);
+ if (!ltt_chan->buf)
+ goto ltt_percpu_alloc_error;
+ ltt_chan->trans_channel_data = ltt_relay_open(tmpname,
+ dir,
+ subbuf_size,
+ n_subbufs,
+ &trace->callbacks,
+ ltt_chan);
+ tmpname_len = strlen(tmpname);
+ if (tmpname_len > 0) {
+ /* Remove final _ for pretty printing */
+ tmpname[tmpname_len-1] = '\0';
+ }
+ if (ltt_chan->trans_channel_data == NULL) {
+ printk(KERN_ERR "LTT : Can't open %s channel for trace %s\n",
+ tmpname, trace_name);
+ goto relay_open_error;
+ }
+
+ err = 0;
+ goto end;
+
+relay_open_error:
+ percpu_free(ltt_chan->buf);
+ltt_percpu_alloc_error:
+ err = EPERM;
+end:
+ kfree(tmpname);
+ return err;
+}
+
+static int ltt_relay_create_dirs(struct ltt_trace_struct *new_trace)
+{
+ new_trace->dentry.trace_root = debugfs_create_dir(new_trace->trace_name,
+ get_ltt_root());
+ if (new_trace->dentry.trace_root == NULL) {
+ printk(KERN_ERR "LTT : Trace directory name %s already taken\n",
+ new_trace->trace_name);
+ return EEXIST;
+ }
+
+ new_trace->callbacks.create_buf_file = ltt_create_buf_file_callback;
+ new_trace->callbacks.remove_buf_file = ltt_remove_buf_file_callback;
+
+ return 0;
+}
+
+/*
+ * LTTng channel flush function.
+ *
+ * Must be called when no tracing is active in the channel, because of
+ * accesses across CPUs.
+ */
+static notrace void ltt_relay_buffer_flush(struct rchan_buf *buf)
+{
+ buf->finalized = 1;
+ ltt_force_switch(buf, FORCE_FLUSH);
+}
+
+static void ltt_relay_async_wakeup_chan(struct ltt_channel_struct *ltt_channel)
+{
+ unsigned int i;
+ struct rchan *rchan = ltt_channel->trans_channel_data;
+
+ for_each_possible_cpu(i) {
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, i);
+
+ if (atomic_read(<t_buf->wakeup_readers) == 1) {
+ atomic_set(<t_buf->wakeup_readers, 0);
+ wake_up_interruptible(&rchan->buf[i]->read_wait);
+ }
+ }
+}
+
+static void ltt_relay_finish_buffer(struct ltt_channel_struct *ltt_channel,
+ unsigned int cpu)
+{
+ struct rchan *rchan = ltt_channel->trans_channel_data;
+
+ if (rchan->buf[cpu]) {
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, cpu);
+ ltt_relay_buffer_flush(rchan->buf[cpu]);
+ ltt_relay_wake_writers(ltt_buf);
+ }
+}
+
+
+static void ltt_relay_finish_channel(struct ltt_channel_struct *ltt_channel)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i)
+ ltt_relay_finish_buffer(ltt_channel, i);
+}
+
+static void ltt_relay_remove_channel(struct ltt_channel_struct *channel)
+{
+ struct rchan *rchan = channel->trans_channel_data;
+
+ ltt_relay_close(rchan);
+ kref_put(&channel->kref, ltt_relay_release_channel);
+}
+
+struct ltt_reserve_switch_offsets {
+ long begin, end, old;
+ long begin_switch, end_switch_current, end_switch_old;
+ long commit_count, reserve_commit_diff;
+ size_t before_hdr_pad, size;
+};
+
+/*
+ * Returns :
+ * 0 if ok
+ * !0 if execution must be aborted.
+ */
+static inline int ltt_relay_try_reserve(
+ struct ltt_channel_struct *ltt_channel,
+ struct ltt_channel_buf_struct *ltt_buf, struct rchan *rchan,
+ struct rchan_buf *buf,
+ struct ltt_reserve_switch_offsets *offsets, size_t data_size,
+ u64 *tsc, unsigned int *rflags, int largest_align)
+{
+ offsets->begin = local_read(<t_buf->offset);
+ offsets->old = offsets->begin;
+ offsets->begin_switch = 0;
+ offsets->end_switch_current = 0;
+ offsets->end_switch_old = 0;
+
+ *tsc = trace_clock_read64();
+ if (last_tsc_overflow(ltt_buf, *tsc))
+ *rflags = LTT_RFLAG_ID_SIZE_TSC;
+
+ if (SUBBUF_OFFSET(offsets->begin, buf->chan) == 0) {
+ offsets->begin_switch = 1; /* For offsets->begin */
+ } else {
+ offsets->size = ltt_get_header_size(ltt_channel,
+ offsets->begin, data_size,
+ &offsets->before_hdr_pad, *rflags);
+ offsets->size += ltt_align(offsets->begin + offsets->size,
+ largest_align)
+ + data_size;
+ if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
+ > buf->chan->subbuf_size) {
+ offsets->end_switch_old = 1; /* For offsets->old */
+ offsets->begin_switch = 1; /* For offsets->begin */
+ }
+ }
+ if (offsets->begin_switch) {
+ long subbuf_index;
+
+ if (offsets->end_switch_old)
+ offsets->begin = SUBBUF_ALIGN(offsets->begin,
+ buf->chan);
+ offsets->begin = offsets->begin + ltt_subbuffer_header_size();
+ /* Test new buffer integrity */
+ subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
+ offsets->reserve_commit_diff =
+ (BUFFER_TRUNC(offsets->begin, buf->chan)
+ >> ltt_channel->n_subbufs_order)
+ - (local_read(<t_buf->commit_count[subbuf_index])
+ & ltt_channel->commit_count_mask);
+ if (offsets->reserve_commit_diff == 0) {
+ /* Next buffer not corrupted. */
+ if (!ltt_channel->overwrite &&
+ (SUBBUF_TRUNC(offsets->begin, buf->chan)
+ - SUBBUF_TRUNC(atomic_long_read(
+ <t_buf->consumed),
+ buf->chan))
+ >= rchan->alloc_size) {
+ /*
+ * We do not overwrite non consumed buffers
+ * and we are full : event is lost.
+ */
+ local_inc(<t_buf->events_lost);
+ return -1;
+ } else {
+ /*
+ * next buffer not corrupted, we are either in
+ * overwrite mode or the buffer is not full.
+ * It's safe to write in this new subbuffer.
+ */
+ }
+ } else {
+ /*
+ * Next subbuffer corrupted. Force pushing reader even
+ * in normal mode. It's safe to write in this new
+ * subbuffer.
+ */
+ }
+ offsets->size = ltt_get_header_size(ltt_channel,
+ offsets->begin, data_size,
+ &offsets->before_hdr_pad, *rflags);
+ offsets->size += ltt_align(offsets->begin + offsets->size,
+ largest_align)
+ + data_size;
+ if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
+ > buf->chan->subbuf_size) {
+ /*
+ * Event too big for subbuffers, report error, don't
+ * complete the sub-buffer switch.
+ */
+ local_inc(<t_buf->events_lost);
+ return -1;
+ } else {
+ /*
+ * We just made a successful buffer switch and the event
+ * fits in the new subbuffer. Let's write.
+ */
+ }
+ } else {
+ /*
+ * Event fits in the current buffer and we are not on a switch
+ * boundary. It's safe to write.
+ */
+ }
+ offsets->end = offsets->begin + offsets->size;
+
+ if ((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0) {
+ /*
+ * The offset_end will fall at the very beginning of the next
+ * subbuffer.
+ */
+ offsets->end_switch_current = 1; /* For offsets->begin */
+ }
+ return 0;
+}
+
+/*
+ * Returns :
+ * 0 if ok
+ * !0 if execution must be aborted.
+ */
+static inline int ltt_relay_try_switch(
+ enum force_switch_mode mode,
+ struct ltt_channel_struct *ltt_channel,
+ struct ltt_channel_buf_struct *ltt_buf, struct rchan *rchan,
+ struct rchan_buf *buf,
+ struct ltt_reserve_switch_offsets *offsets,
+ u64 *tsc)
+{
+ long subbuf_index;
+
+ offsets->begin = local_read(<t_buf->offset);
+ offsets->old = offsets->begin;
+ offsets->begin_switch = 0;
+ offsets->end_switch_old = 0;
+
+ *tsc = trace_clock_read64();
+
+ if (SUBBUF_OFFSET(offsets->begin, buf->chan) != 0) {
+ offsets->begin = SUBBUF_ALIGN(offsets->begin, buf->chan);
+ offsets->end_switch_old = 1;
+ } else {
+ /* we do not have to switch : buffer is empty */
+ return -1;
+ }
+ if (mode == FORCE_ACTIVE)
+ offsets->begin += ltt_subbuffer_header_size();
+ /*
+ * Always begin_switch in FORCE_ACTIVE mode.
+ * Test new buffer integrity
+ */
+ subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
+ offsets->reserve_commit_diff =
+ (BUFFER_TRUNC(offsets->begin, buf->chan)
+ >> ltt_channel->n_subbufs_order)
+ - (local_read(<t_buf->commit_count[subbuf_index])
+ & ltt_channel->commit_count_mask);
+ if (offsets->reserve_commit_diff == 0) {
+ /* Next buffer not corrupted. */
+ if (mode == FORCE_ACTIVE
+ && !ltt_channel->overwrite
+ && offsets->begin - atomic_long_read(<t_buf->consumed)
+ >= rchan->alloc_size) {
+ /*
+ * We do not overwrite non consumed buffers and we are
+ * full : ignore switch while tracing is active.
+ */
+ return -1;
+ }
+ } else {
+ /*
+ * Next subbuffer corrupted. Force pushing reader even in normal
+ * mode
+ */
+ }
+ offsets->end = offsets->begin;
+ return 0;
+}
+
+static inline void ltt_reserve_push_reader(
+ struct ltt_channel_struct *ltt_channel,
+ struct ltt_channel_buf_struct *ltt_buf,
+ struct rchan *rchan,
+ struct rchan_buf *buf,
+ struct ltt_reserve_switch_offsets *offsets)
+{
+ long consumed_old, consumed_new;
+
+ do {
+ consumed_old = atomic_long_read(<t_buf->consumed);
+ /*
+ * If buffer is in overwrite mode, push the reader consumed
+ * count if the write position has reached it and we are not
+ * at the first iteration (don't push the reader farther than
+ * the writer). This operation can be done concurrently by many
+ * writers in the same buffer, the writer being at the farthest
+ * write position sub-buffer index in the buffer being the one
+ * which will win this loop.
+ * If the buffer is not in overwrite mode, pushing the reader
+ * only happens if a sub-buffer is corrupted.
+ */
+ if ((SUBBUF_TRUNC(offsets->end-1, buf->chan)
+ - SUBBUF_TRUNC(consumed_old, buf->chan))
+ >= rchan->alloc_size)
+ consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
+ else {
+ consumed_new = consumed_old;
+ break;
+ }
+ } while (atomic_long_cmpxchg(<t_buf->consumed, consumed_old,
+ consumed_new) != consumed_old);
+
+ if (consumed_old != consumed_new) {
+ /*
+ * Reader pushed : we are the winner of the push, we can
+ * therefore reequilibrate reserve and commit. Atomic increment
+ * of the commit count permits other writers to play around
+ * with this variable before us. We keep track of
+ * corrupted_subbuffers even in overwrite mode :
+ * we never want to write over a non completely committed
+ * sub-buffer : possible causes : the buffer size is too low
+ * compared to the unordered data input, or there is a writer
+ * that died between the reserve and the commit.
+ */
+ if (offsets->reserve_commit_diff) {
+ /*
+ * We have to alter the sub-buffer commit count.
+ * We do not deliver the previous subbuffer, given it
+ * was either corrupted or not consumed (overwrite
+ * mode).
+ */
+ local_add(offsets->reserve_commit_diff,
+ <t_buf->commit_count[
+ SUBBUF_INDEX(offsets->begin,
+ buf->chan)]);
+ if (!ltt_channel->overwrite
+ || offsets->reserve_commit_diff
+ != rchan->subbuf_size) {
+ /*
+ * The reserve commit diff was not subbuf_size :
+ * it means the subbuffer was partly written to
+ * and is therefore corrupted. If it is multiple
+ * of subbuffer size and we are in flight
+ * recorder mode, we are skipping over a whole
+ * subbuffer.
+ */
+ local_inc(<t_buf->corrupted_subbuffers);
+ }
+ }
+ }
+}
+
+
+/*
+ * ltt_reserve_switch_old_subbuf: switch old subbuffer
+ *
+ * Concurrency safe because we are the last and only thread to alter this
+ * sub-buffer. As long as it is not delivered and read, no other thread can
+ * alter the offset, alter the reserve_count or call the
+ * client_buffer_end_callback on this sub-buffer.
+ *
+ * The only remaining threads could be the ones with pending commits. They will
+ * have to do the deliver themselves. Not concurrency safe in overwrite mode.
+ * We detect corrupted subbuffers with commit and reserve counts. We keep a
+ * corrupted sub-buffers count and push the readers across these sub-buffers.
+ *
+ * Not concurrency safe if a writer is stalled in a subbuffer and another writer
+ * switches in, finding out it's corrupted. The result will be than the old
+ * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
+ * will be declared corrupted too because of the commit count adjustment.
+ *
+ * Note : offset_old should never be 0 here.
+ */
+static inline void ltt_reserve_switch_old_subbuf(
+ struct ltt_channel_struct *ltt_channel,
+ struct ltt_channel_buf_struct *ltt_buf, struct rchan *rchan,
+ struct rchan_buf *buf,
+ struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
+{
+ long oldidx = SUBBUF_INDEX(offsets->old - 1, rchan);
+
+ ltt_channel->buffer_end(buf, *tsc, offsets->old, oldidx);
+ /* Must write buffer end before incrementing commit count */
+ smp_wmb();
+ offsets->commit_count =
+ local_add_return(rchan->subbuf_size
+ - (SUBBUF_OFFSET(offsets->old - 1, rchan)
+ + 1),
+ <t_buf->commit_count[oldidx]);
+ if ((BUFFER_TRUNC(offsets->old - 1, rchan)
+ >> ltt_channel->n_subbufs_order)
+ - ((offsets->commit_count - rchan->subbuf_size)
+ & ltt_channel->commit_count_mask) == 0)
+ ltt_deliver(buf, oldidx, NULL);
+}
+
+/*
+ * ltt_reserve_switch_new_subbuf: Populate new subbuffer.
+ *
+ * This code can be executed unordered : writers may already have written to the
+ * sub-buffer before this code gets executed, caution. The commit makes sure
+ * that this code is executed before the deliver of this sub-buffer.
+ */
+static inline void ltt_reserve_switch_new_subbuf(
+ struct ltt_channel_struct *ltt_channel,
+ struct ltt_channel_buf_struct *ltt_buf, struct rchan *rchan,
+ struct rchan_buf *buf,
+ struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
+{
+ long beginidx = SUBBUF_INDEX(offsets->begin, rchan);
+
+ ltt_channel->buffer_begin(buf, *tsc, beginidx);
+ /* Must write buffer end before incrementing commit count */
+ smp_wmb();
+ offsets->commit_count = local_add_return(ltt_subbuffer_header_size(),
+ <t_buf->commit_count[beginidx]);
+ /* Check if the written buffer has to be delivered */
+ if ((BUFFER_TRUNC(offsets->begin, rchan)
+ >> ltt_channel->n_subbufs_order)
+ - ((offsets->commit_count - rchan->subbuf_size)
+ & ltt_channel->commit_count_mask) == 0)
+ ltt_deliver(buf, beginidx, NULL);
+}
+
+
+/*
+ * ltt_reserve_end_switch_current: finish switching current subbuffer
+ *
+ * Concurrency safe because we are the last and only thread to alter this
+ * sub-buffer. As long as it is not delivered and read, no other thread can
+ * alter the offset, alter the reserve_count or call the
+ * client_buffer_end_callback on this sub-buffer.
+ *
+ * The only remaining threads could be the ones with pending commits. They will
+ * have to do the deliver themselves. Not concurrency safe in overwrite mode.
+ * We detect corrupted subbuffers with commit and reserve counts. We keep a
+ * corrupted sub-buffers count and push the readers across these sub-buffers.
+ *
+ * Not concurrency safe if a writer is stalled in a subbuffer and another writer
+ * switches in, finding out it's corrupted. The result will be than the old
+ * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
+ * will be declared corrupted too because of the commit count adjustment.
+ */
+static inline void ltt_reserve_end_switch_current(
+ struct ltt_channel_struct *ltt_channel,
+ struct ltt_channel_buf_struct *ltt_buf, struct rchan *rchan,
+ struct rchan_buf *buf,
+ struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
+{
+ long endidx = SUBBUF_INDEX(offsets->end - 1, rchan);
+
+ ltt_channel->buffer_end(buf, *tsc, offsets->end, endidx);
+ /* Must write buffer begin before incrementing commit count */
+ smp_wmb();
+ offsets->commit_count =
+ local_add_return(rchan->subbuf_size
+ - (SUBBUF_OFFSET(offsets->end - 1, rchan)
+ + 1),
+ <t_buf->commit_count[endidx]);
+ if ((BUFFER_TRUNC(offsets->end - 1, rchan)
+ >> ltt_channel->n_subbufs_order)
+ - ((offsets->commit_count - rchan->subbuf_size)
+ & ltt_channel->commit_count_mask) == 0)
+ ltt_deliver(buf, endidx, NULL);
+}
+
+/**
+ * ltt_relay_reserve_slot - Atomic slot reservation in a LTTng buffer.
+ * @trace: the trace structure to log to.
+ * @ltt_channel: channel structure
+ * @transport_data: data structure specific to ltt relay
+ * @data_size: size of the variable length data to log.
+ * @slot_size: pointer to total size of the slot (out)
+ * @buf_offset : pointer to reserved buffer offset (out)
+ * @tsc: pointer to the tsc at the slot reservation (out)
+ * @cpu: cpuid
+ *
+ * Return : -ENOSPC if not enough space, else returns 0.
+ * It will take care of sub-buffer switching.
+ */
+static notrace int ltt_relay_reserve_slot(struct ltt_trace_struct *trace,
+ struct ltt_channel_struct *ltt_channel, void **transport_data,
+ size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
+ unsigned int *rflags, int largest_align, int cpu)
+{
+ struct rchan *rchan = ltt_channel->trans_channel_data;
+ struct rchan_buf *buf = *transport_data =
+ rchan->buf[cpu];
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ struct ltt_reserve_switch_offsets offsets;
+
+ offsets.reserve_commit_diff = 0;
+ offsets.size = 0;
+
+ /*
+ * Perform retryable operations.
+ */
+ if (__get_cpu_var(ltt_nesting) > 4) {
+ local_inc(<t_buf->events_lost);
+ return -EPERM;
+ }
+ do {
+ if (ltt_relay_try_reserve(ltt_channel, ltt_buf,
+ rchan, buf, &offsets, data_size, tsc, rflags,
+ largest_align))
+ return -ENOSPC;
+ } while (local_cmpxchg(<t_buf->offset, offsets.old,
+ offsets.end) != offsets.old);
+
+ /*
+ * Atomically update last_tsc. This update races against concurrent
+ * atomic updates, but the race will always cause supplementary full TSC
+ * events, never the opposite (missing a full TSC event when it would be
+ * needed).
+ */
+ save_last_tsc(ltt_buf, *tsc);
+
+ /*
+ * Push the reader if necessary
+ */
+ ltt_reserve_push_reader(ltt_channel, ltt_buf, rchan, buf, &offsets);
+
+ /*
+ * Switch old subbuffer if needed.
+ */
+ if (offsets.end_switch_old)
+ ltt_reserve_switch_old_subbuf(ltt_channel, ltt_buf, rchan, buf,
+ &offsets, tsc);
+
+ /*
+ * Populate new subbuffer.
+ */
+ if (offsets.begin_switch)
+ ltt_reserve_switch_new_subbuf(ltt_channel, ltt_buf, rchan,
+ buf, &offsets, tsc);
+
+ if (offsets.end_switch_current)
+ ltt_reserve_end_switch_current(ltt_channel, ltt_buf, rchan,
+ buf, &offsets, tsc);
+
+ *slot_size = offsets.size;
+ *buf_offset = offsets.begin + offsets.before_hdr_pad;
+ return 0;
+}
+
+/*
+ * Force a sub-buffer switch for a per-cpu buffer. This operation is
+ * completely reentrant : can be called while tracing is active with
+ * absolutely no lock held.
+ *
+ * Note, however, that as a local_cmpxchg is used for some atomic
+ * operations, this function must be called from the CPU which owns the buffer
+ * for a ACTIVE flush.
+ */
+static notrace void ltt_force_switch(struct rchan_buf *buf,
+ enum force_switch_mode mode)
+{
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ struct rchan *rchan = ltt_channel->trans_channel_data;
+ struct ltt_reserve_switch_offsets offsets;
+ u64 tsc;
+
+ offsets.reserve_commit_diff = 0;
+ offsets.size = 0;
+
+ /*
+ * Perform retryable operations.
+ */
+ do {
+ if (ltt_relay_try_switch(mode, ltt_channel, ltt_buf,
+ rchan, buf, &offsets, &tsc))
+ return;
+ } while (local_cmpxchg(<t_buf->offset, offsets.old,
+ offsets.end) != offsets.old);
+
+ /*
+ * Atomically update last_tsc. This update races against concurrent
+ * atomic updates, but the race will always cause supplementary full TSC
+ * events, never the opposite (missing a full TSC event when it would be
+ * needed).
+ */
+ save_last_tsc(ltt_buf, tsc);
+
+ /*
+ * Push the reader if necessary
+ */
+ if (mode == FORCE_ACTIVE)
+ ltt_reserve_push_reader(ltt_channel, ltt_buf, rchan,
+ buf, &offsets);
+
+ /*
+ * Switch old subbuffer if needed.
+ */
+ if (offsets.end_switch_old)
+ ltt_reserve_switch_old_subbuf(ltt_channel, ltt_buf, rchan, buf,
+ &offsets, &tsc);
+
+ /*
+ * Populate new subbuffer.
+ */
+ if (mode == FORCE_ACTIVE)
+ ltt_reserve_switch_new_subbuf(ltt_channel,
+ ltt_buf, rchan, buf, &offsets, &tsc);
+}
+
+/*
+ * for flight recording. must be called after relay_commit.
+ * This function decrements de subbuffer's lost_size each time the commit count
+ * reaches back the reserve offset (module subbuffer size). It is useful for
+ * crash dump.
+ * We use slot_size - 1 to make sure we deal correctly with the case where we
+ * fill the subbuffer completely (so the subbuf index stays in the previous
+ * subbuffer).
+ */
+#ifdef CONFIG_LTT_VMCORE
+static inline void ltt_write_commit_counter(struct rchan_buf *buf,
+ long buf_offset, size_t slot_size)
+{
+ struct ltt_channel_struct *ltt_channel =
+ (struct ltt_channel_struct *)buf->chan->private_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ struct ltt_subbuffer_header *header;
+ long offset, subbuf_idx, commit_count;
+ uint32_t lost_old, lost_new;
+
+ subbuf_idx = SUBBUF_INDEX(buf_offset - 1, buf->chan);
+ offset = buf_offset + slot_size;
+ header = (struct ltt_subbuffer_header *)
+ ltt_relay_offset_address(buf,
+ subbuf_idx * buf->chan->subbuf_size);
+ for (;;) {
+ lost_old = header->lost_size;
+ commit_count =
+ local_read(<t_buf->commit_count[subbuf_idx]);
+ /* SUBBUF_OFFSET includes commit_count_mask */
+ if (!SUBBUF_OFFSET(offset - commit_count, buf->chan)) {
+ lost_new = (uint32_t)buf->chan->subbuf_size
+ - SUBBUF_OFFSET(commit_count, buf->chan);
+ lost_old = cmpxchg_local(&header->lost_size, lost_old,
+ lost_new);
+ if (lost_old <= lost_new)
+ break;
+ } else {
+ break;
+ }
+ }
+}
+#else
+static inline void ltt_write_commit_counter(struct rchan_buf *buf,
+ long buf_offset, size_t slot_size)
+{
+}
+#endif
+
+/*
+ * Atomic unordered slot commit. Increments the commit count in the
+ * specified sub-buffer, and delivers it if necessary.
+ *
+ * Parameters:
+ *
+ * @ltt_channel : channel structure
+ * @transport_data: transport-specific data
+ * @buf_offset : offset following the event header.
+ * @slot_size : size of the reserved slot.
+ */
+static notrace void ltt_relay_commit_slot(
+ struct ltt_channel_struct *ltt_channel,
+ void **transport_data, long buf_offset, size_t slot_size)
+{
+ struct rchan_buf *buf = *transport_data;
+ struct ltt_channel_buf_struct *ltt_buf =
+ percpu_ptr(ltt_channel->buf, buf->cpu);
+ struct rchan *rchan = buf->chan;
+ long offset_end = buf_offset;
+ long endidx = SUBBUF_INDEX(offset_end - 1, rchan);
+ long commit_count;
+
+ /* Must write slot data before incrementing commit count */
+ smp_wmb();
+ commit_count = local_add_return(slot_size,
+ <t_buf->commit_count[endidx]);
+ /* Check if all commits have been done */
+ if ((BUFFER_TRUNC(offset_end - 1, rchan)
+ >> ltt_channel->n_subbufs_order)
+ - ((commit_count - rchan->subbuf_size)
+ & ltt_channel->commit_count_mask) == 0)
+ ltt_deliver(buf, endidx, NULL);
+ /*
+ * Update lost_size for each commit. It's needed only for extracting
+ * ltt buffers from vmcore, after crash.
+ */
+ ltt_write_commit_counter(buf, buf_offset, slot_size);
+}
+
+/*
+ * This is called with preemption disabled when user space has requested
+ * blocking mode. If one of the active traces has free space below a
+ * specific threshold value, we reenable preemption and block.
+ */
+static int ltt_relay_user_blocking(struct ltt_trace_struct *trace,
+ unsigned int chan_index, size_t data_size,
+ struct user_dbg_data *dbg)
+{
+ struct rchan *rchan;
+ struct ltt_channel_buf_struct *ltt_buf;
+ struct ltt_channel_struct *channel;
+ struct rchan_buf *relay_buf;
+ int cpu;
+ DECLARE_WAITQUEUE(wait, current);
+
+ channel = &trace->channels[chan_index];
+ rchan = channel->trans_channel_data;
+ cpu = smp_processor_id();
+ relay_buf = rchan->buf[cpu];
+ ltt_buf = percpu_ptr(channel->buf, cpu);
+
+ /*
+ * Check if data is too big for the channel : do not
+ * block for it.
+ */
+ if (LTT_RESERVE_CRITICAL + data_size > relay_buf->chan->subbuf_size)
+ return 0;
+
+ /*
+ * If free space too low, we block. We restart from the
+ * beginning after we resume (cpu id may have changed
+ * while preemption is active).
+ */
+ spin_lock(<t_buf->full_lock);
+ if (!channel->overwrite) {
+ dbg->write = local_read(<t_buf->offset);
+ dbg->read = atomic_long_read(<t_buf->consumed);
+ dbg->avail_size = dbg->write + LTT_RESERVE_CRITICAL + data_size
+ - SUBBUF_TRUNC(dbg->read,
+ relay_buf->chan);
+ if (dbg->avail_size > rchan->alloc_size) {
+ __set_current_state(TASK_INTERRUPTIBLE);
+ add_wait_queue(<t_buf->write_wait, &wait);
+ spin_unlock(<t_buf->full_lock);
+ preempt_enable();
+ schedule();
+ __set_current_state(TASK_RUNNING);
+ remove_wait_queue(<t_buf->write_wait, &wait);
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+ preempt_disable();
+ return 1;
+ }
+ }
+ spin_unlock(<t_buf->full_lock);
+ return 0;
+}
+
+static void ltt_relay_print_user_errors(struct ltt_trace_struct *trace,
+ unsigned int chan_index, size_t data_size,
+ struct user_dbg_data *dbg, int cpu)
+{
+ struct rchan *rchan;
+ struct ltt_channel_buf_struct *ltt_buf;
+ struct ltt_channel_struct *channel;
+ struct rchan_buf *relay_buf;
+
+ channel = &trace->channels[chan_index];
+ rchan = channel->trans_channel_data;
+ relay_buf = rchan->buf[cpu];
+ ltt_buf = percpu_ptr(channel->buf, cpu);
+
+ printk(KERN_ERR "Error in LTT usertrace : "
+ "buffer full : event lost in blocking "
+ "mode. Increase LTT_RESERVE_CRITICAL.\n");
+ printk(KERN_ERR "LTT nesting level is %u.\n",
+ per_cpu(ltt_nesting, cpu));
+ printk(KERN_ERR "LTT avail size %lu.\n",
+ dbg->avail_size);
+ printk(KERN_ERR "avai write : %lu, read : %lu\n",
+ dbg->write, dbg->read);
+
+ dbg->write = local_read(<t_buf->offset);
+ dbg->read = atomic_long_read(<t_buf->consumed);
+
+ printk(KERN_ERR "LTT cur size %lu.\n",
+ dbg->write + LTT_RESERVE_CRITICAL + data_size
+ - SUBBUF_TRUNC(dbg->read, relay_buf->chan));
+ printk(KERN_ERR "cur write : %lu, read : %lu\n",
+ dbg->write, dbg->read);
+}
+
+static struct ltt_transport ltt_relay_transport = {
+ .name = "relay",
+ .owner = THIS_MODULE,
+ .ops = {
+ .create_dirs = ltt_relay_create_dirs,
+ .remove_dirs = ltt_relay_remove_dirs,
+ .create_channel = ltt_relay_create_channel,
+ .finish_channel = ltt_relay_finish_channel,
+ .remove_channel = ltt_relay_remove_channel,
+ .wakeup_channel = ltt_relay_async_wakeup_chan,
+ .commit_slot = ltt_relay_commit_slot,
+ .reserve_slot = ltt_relay_reserve_slot,
+ .user_blocking = ltt_relay_user_blocking,
+ .user_errors = ltt_relay_print_user_errors,
+ },
+};
+
+static int __init ltt_relay_init(void)
+{
+ printk(KERN_INFO "LTT : ltt-relay init\n");
+
+ ltt_file_operations = ltt_relay_file_operations;
+ ltt_file_operations.owner = THIS_MODULE;
+ ltt_file_operations.open = ltt_open;
+ ltt_file_operations.release = ltt_release;
+ ltt_file_operations.poll = ltt_poll;
+ ltt_file_operations.splice_read = ltt_relay_file_splice_read,
+ ltt_file_operations.ioctl = ltt_ioctl;
+#ifdef CONFIG_COMPAT
+ ltt_file_operations.compat_ioctl = ltt_compat_ioctl;
+#endif
+
+ ltt_transport_register(<t_relay_transport);
+
+ return 0;
+}
+
+static void __exit ltt_relay_exit(void)
+{
+ printk(KERN_INFO "LTT : ltt-relay exit\n");
+
+ ltt_transport_unregister(<t_relay_transport);
+}
+
+module_init(ltt_relay_init);
+module_exit(ltt_relay_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Next Generation Lockless Relay");
projects / ust.git / commitdiff
