ust: add kernel ltt-channel.[ch], removing the ltt- part

diff --git a/libtracing/channels.c b/libtracing/channels.c
new file mode 100644 (file)
index 0000000..bd9c508
--- /dev/null
+++ b/libtracing/channels.c
@@ -0,0 +1,338 @@
+/*
+ * ltt/ltt-channels.c
+ *
+ * (C) Copyright 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * LTTng channel management.
+ *
+ * Author:
+ *     Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ */
+
+#include <linux/module.h>
+#include <linux/ltt-channels.h>
+#include <linux/mutex.h>
+#include <linux/vmalloc.h>
+
+/*
+ * ltt_channel_mutex may be nested inside the LTT trace mutex.
+ * ltt_channel_mutex mutex may be nested inside markers mutex.
+ */
+static DEFINE_MUTEX(ltt_channel_mutex);
+static LIST_HEAD(ltt_channels);
+/*
+ * Index of next channel in array. Makes sure that as long as a trace channel is
+ * allocated, no array index will be re-used when a channel is freed and then
+ * another channel is allocated. This index is cleared and the array indexeds
+ * get reassigned when the index_kref goes back to 0, which indicates that no
+ * more trace channels are allocated.
+ */
+static unsigned int free_index;
+static struct kref index_kref; /* Keeps track of allocated trace channels */
+
+static struct ltt_channel_setting *lookup_channel(const char *name)
+{
+       struct ltt_channel_setting *iter;
+
+       list_for_each_entry(iter, &ltt_channels, list)
+               if (strcmp(name, iter->name) == 0)
+                       return iter;
+       return NULL;
+}
+
+/*
+ * Must be called when channel refcount falls to 0 _and_ also when the last
+ * trace is freed. This function is responsible for compacting the channel and
+ * event IDs when no users are active.
+ *
+ * Called with lock_markers() and channels mutex held.
+ */
+static void release_channel_setting(struct kref *kref)
+{
+       struct ltt_channel_setting *setting = container_of(kref,
+               struct ltt_channel_setting, kref);
+       struct ltt_channel_setting *iter;
+
+       if (atomic_read(&index_kref.refcount) == 0
+           && atomic_read(&setting->kref.refcount) == 0) {
+               list_del(&setting->list);
+               kfree(setting);
+
+               free_index = 0;
+               list_for_each_entry(iter, &ltt_channels, list) {
+                       iter->index = free_index++;
+                       iter->free_event_id = 0;
+               }
+               markers_compact_event_ids();
+       }
+}
+
+/*
+ * Perform channel index compaction when the last trace channel is freed.
+ *
+ * Called with lock_markers() and channels mutex held.
+ */
+static void release_trace_channel(struct kref *kref)
+{
+       struct ltt_channel_setting *iter, *n;
+
+       list_for_each_entry_safe(iter, n, &ltt_channels, list)
+               release_channel_setting(&iter->kref);
+}
+
+/**
+ * ltt_channels_register - Register a trace channel.
+ * @name: channel name
+ *
+ * Uses refcounting.
+ */
+int ltt_channels_register(const char *name)
+{
+       struct ltt_channel_setting *setting;
+       int ret = 0;
+
+       mutex_lock(&ltt_channel_mutex);
+       setting = lookup_channel(name);
+       if (setting) {
+               if (atomic_read(&setting->kref.refcount) == 0)
+                       goto init_kref;
+               else {
+                       kref_get(&setting->kref);
+                       goto end;
+               }
+       }
+       setting = kzalloc(sizeof(*setting), GFP_KERNEL);
+       if (!setting) {
+               ret = -ENOMEM;
+               goto end;
+       }
+       list_add(&setting->list, &ltt_channels);
+       strncpy(setting->name, name, PATH_MAX-1);
+       setting->index = free_index++;
+init_kref:
+       kref_init(&setting->kref);
+end:
+       mutex_unlock(&ltt_channel_mutex);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_channels_register);
+
+/**
+ * ltt_channels_unregister - Unregister a trace channel.
+ * @name: channel name
+ *
+ * Must be called with markers mutex held.
+ */
+int ltt_channels_unregister(const char *name)
+{
+       struct ltt_channel_setting *setting;
+       int ret = 0;
+
+       mutex_lock(&ltt_channel_mutex);
+       setting = lookup_channel(name);
+       if (!setting || atomic_read(&setting->kref.refcount) == 0) {
+               ret = -ENOENT;
+               goto end;
+       }
+       kref_put(&setting->kref, release_channel_setting);
+end:
+       mutex_unlock(&ltt_channel_mutex);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_channels_unregister);
+
+/**
+ * ltt_channels_set_default - Set channel default behavior.
+ * @name: default channel name
+ * @subbuf_size: size of the subbuffers
+ * @subbuf_cnt: number of subbuffers
+ */
+int ltt_channels_set_default(const char *name,
+                            unsigned int subbuf_size,
+                            unsigned int subbuf_cnt)
+{
+       struct ltt_channel_setting *setting;
+       int ret = 0;
+
+       mutex_lock(&ltt_channel_mutex);
+       setting = lookup_channel(name);
+       if (!setting || atomic_read(&setting->kref.refcount) == 0) {
+               ret = -ENOENT;
+               goto end;
+       }
+       setting->subbuf_size = subbuf_size;
+       setting->subbuf_cnt = subbuf_cnt;
+end:
+       mutex_unlock(&ltt_channel_mutex);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_channels_set_default);
+
+/**
+ * ltt_channels_get_name_from_index - get channel name from channel index
+ * @index: channel index
+ *
+ * Allows to lookup the channel name given its index. Done to keep the name
+ * information outside of each trace channel instance.
+ */
+const char *ltt_channels_get_name_from_index(unsigned int index)
+{
+       struct ltt_channel_setting *iter;
+
+       list_for_each_entry(iter, &ltt_channels, list)
+               if (iter->index == index && atomic_read(&iter->kref.refcount))
+                       return iter->name;
+       return NULL;
+}
+EXPORT_SYMBOL_GPL(ltt_channels_get_name_from_index);
+
+static struct ltt_channel_setting *
+ltt_channels_get_setting_from_name(const char *name)
+{
+       struct ltt_channel_setting *iter;
+
+       list_for_each_entry(iter, &ltt_channels, list)
+               if (!strcmp(iter->name, name)
+                   && atomic_read(&iter->kref.refcount))
+                       return iter;
+       return NULL;
+}
+
+/**
+ * ltt_channels_get_index_from_name - get channel index from channel name
+ * @name: channel name
+ *
+ * Allows to lookup the channel index given its name. Done to keep the name
+ * information outside of each trace channel instance.
+ * Returns -1 if not found.
+ */
+int ltt_channels_get_index_from_name(const char *name)
+{
+       struct ltt_channel_setting *setting;
+
+       setting = ltt_channels_get_setting_from_name(name);
+       if (setting)
+               return setting->index;
+       else
+               return -1;
+}
+EXPORT_SYMBOL_GPL(ltt_channels_get_index_from_name);
+
+/**
+ * ltt_channels_trace_alloc - Allocate channel structures for a trace
+ * @subbuf_size: subbuffer size. 0 uses default.
+ * @subbuf_cnt: number of subbuffers per per-cpu buffers. 0 uses default.
+ * @flags: Default channel flags
+ *
+ * Use the current channel list to allocate the channels for a trace.
+ * Called with trace lock held. Does not perform the trace buffer allocation,
+ * because we must let the user overwrite specific channel sizes.
+ */
+struct ltt_channel_struct *ltt_channels_trace_alloc(unsigned int *nr_channels,
+                                                   int overwrite,
+                                                   int active)
+{
+       struct ltt_channel_struct *channel = NULL;
+       struct ltt_channel_setting *iter;
+
+       mutex_lock(&ltt_channel_mutex);
+       if (!free_index)
+               goto end;
+       if (!atomic_read(&index_kref.refcount))
+               kref_init(&index_kref);
+       else
+               kref_get(&index_kref);
+       *nr_channels = free_index;
+       channel = kzalloc(sizeof(struct ltt_channel_struct) * free_index,
+                         GFP_KERNEL);
+       if (!channel)
+               goto end;
+       list_for_each_entry(iter, &ltt_channels, list) {
+               if (!atomic_read(&iter->kref.refcount))
+                       continue;
+               channel[iter->index].subbuf_size = iter->subbuf_size;
+               channel[iter->index].subbuf_cnt = iter->subbuf_cnt;
+               channel[iter->index].overwrite = overwrite;
+               channel[iter->index].active = active;
+               channel[iter->index].channel_name = iter->name;
+       }
+end:
+       mutex_unlock(&ltt_channel_mutex);
+       return channel;
+}
+EXPORT_SYMBOL_GPL(ltt_channels_trace_alloc);
+
+/**
+ * ltt_channels_trace_free - Free one trace's channels
+ * @channels: channels to free
+ *
+ * Called with trace lock held. The actual channel buffers must be freed before
+ * this function is called.
+ */
+void ltt_channels_trace_free(struct ltt_channel_struct *channels)
+{
+       lock_markers();
+       mutex_lock(&ltt_channel_mutex);
+       kfree(channels);
+       kref_put(&index_kref, release_trace_channel);
+       mutex_unlock(&ltt_channel_mutex);
+       unlock_markers();
+}
+EXPORT_SYMBOL_GPL(ltt_channels_trace_free);
+
+/**
+ * _ltt_channels_get_event_id - get next event ID for a marker
+ * @channel: channel name
+ * @name: event name
+ *
+ * Returns a unique event ID (for this channel) or < 0 on error.
+ * Must be called with channels mutex held.
+ */
+int _ltt_channels_get_event_id(const char *channel, const char *name)
+{
+       struct ltt_channel_setting *setting;
+       int ret;
+
+       setting = ltt_channels_get_setting_from_name(channel);
+       if (!setting) {
+               ret = -ENOENT;
+               goto end;
+       }
+       if (strcmp(channel, "metadata") == 0) {
+               if (strcmp(name, "core_marker_id") == 0)
+                       ret = 0;
+               else if (strcmp(name, "core_marker_format") == 0)
+                       ret = 1;
+               else
+                       ret = -ENOENT;
+               goto end;
+       }
+       if (setting->free_event_id == EVENTS_PER_CHANNEL - 1) {
+               ret = -ENOSPC;
+               goto end;
+       }
+       ret = setting->free_event_id++;
+end:
+       return ret;
+}
+
+/**
+ * ltt_channels_get_event_id - get next event ID for a marker
+ * @channel: channel name
+ * @name: event name
+ *
+ * Returns a unique event ID (for this channel) or < 0 on error.
+ */
+int ltt_channels_get_event_id(const char *channel, const char *name)
+{
+       int ret;
+
+       mutex_lock(&ltt_channel_mutex);
+       ret = _ltt_channels_get_event_id(channel, name);
+       mutex_unlock(&ltt_channel_mutex);
+       return ret;
+}
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Next Generation Channel Management");

diff --git a/libtracing/channels.h b/libtracing/channels.h
new file mode 100644 (file)
index 0000000..4a3924b
--- /dev/null
+++ b/libtracing/channels.h
@@ -0,0 +1,77 @@
+#ifndef _LTT_CHANNELS_H
+#define _LTT_CHANNELS_H
+
+/*
+ * Copyright (C) 2008 Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
+ *
+ * Dynamic tracer channel allocation.
+ */
+
+#include <linux/limits.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+
+#define EVENTS_PER_CHANNEL     65536
+
+struct ltt_trace_struct;
+struct rchan_buf;
+
+struct ltt_channel_struct {
+       /* First 32 bytes cache-hot cacheline */
+       struct ltt_trace_struct *trace;
+       void *buf;
+       void *trans_channel_data;
+       int overwrite:1;
+       int active:1;
+       unsigned int n_subbufs_order;
+       unsigned long commit_count_mask;        /*
+                                                * Commit count mask, removing
+                                                * the MSBs corresponding to
+                                                * bits used to represent the
+                                                * subbuffer index.
+                                                */
+       /* End of first 32 bytes cacheline */
+
+       /*
+        * buffer_begin - called on buffer-switch to a new sub-buffer
+        * @buf: the channel buffer containing the new sub-buffer
+        */
+       void (*buffer_begin) (struct rchan_buf *buf,
+                       u64 tsc, unsigned int subbuf_idx);
+       /*
+        * buffer_end - called on buffer-switch to a new sub-buffer
+        * @buf: the channel buffer containing the previous sub-buffer
+        */
+       void (*buffer_end) (struct rchan_buf *buf,
+                       u64 tsc, unsigned int offset, unsigned int subbuf_idx);
+       struct kref kref;       /* Channel transport reference count */
+       unsigned int subbuf_size;
+       unsigned int subbuf_cnt;
+       const char *channel_name;
+} ____cacheline_aligned;
+
+struct ltt_channel_setting {
+       unsigned int subbuf_size;
+       unsigned int subbuf_cnt;
+       struct kref kref;       /* Number of references to structure content */
+       struct list_head list;
+       unsigned int index;     /* index of channel in trace channel array */
+       u16 free_event_id;      /* Next event ID to allocate */
+       char name[PATH_MAX];
+};
+
+int ltt_channels_register(const char *name);
+int ltt_channels_unregister(const char *name);
+int ltt_channels_set_default(const char *name,
+                            unsigned int subbuf_size,
+                            unsigned int subbuf_cnt);
+const char *ltt_channels_get_name_from_index(unsigned int index);
+int ltt_channels_get_index_from_name(const char *name);
+struct ltt_channel_struct *ltt_channels_trace_alloc(unsigned int *nr_channels,
+                                                   int overwrite,
+                                                   int active);
+void ltt_channels_trace_free(struct ltt_channel_struct *channels);
+int _ltt_channels_get_event_id(const char *channel, const char *name);
+int ltt_channels_get_event_id(const char *channel, const char *name);
+
+#endif /* _LTT_CHANNELS_H */