libust/relay.h

   1 /*
   2  * linux/include/linux/ltt-relay.h
   3  *
   4  * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
   5  * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
   6  * Copyright (C) 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
   7  *
   8  * CONFIG_RELAY definitions and declarations
   9  */
  10
  11 #ifndef _LINUX_LTT_RELAY_H
  12 #define _LINUX_LTT_RELAY_H
  13
  14 //ust// #include <linux/types.h>
  15 //ust// #include <linux/sched.h>
  16 //ust// #include <linux/timer.h>
  17 //ust// #include <linux/wait.h>
  18 //ust// #include <linux/list.h>
  19 //ust// #include <linux/fs.h>
  20 //ust// #include <linux/poll.h>
  21 //ust// #include <linux/kref.h>
  22 //ust// #include <linux/mm.h>
  23 //ust// #include <linux/ltt-core.h>
  24 #include <assert.h>
  25 #include "kref.h"
  26 //#include "list.h"
  27 #include "channels.h"
  28 #include "buffer.h"
  29
  30 /* Needs a _much_ better name... */
  31 #define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE)
  32
  33 /*
  34  * Tracks changes to rchan/rchan_buf structs
  35  */
  36 #define LTT_RELAY_CHANNEL_VERSION               8
  37
  38 struct rchan_buf;
  39
  40 struct buf_page {
  41         struct page *page;
  42         struct rchan_buf *buf;  /* buffer the page belongs to */
  43         size_t offset;          /* page offset in the buffer */
  44         struct list_head list;  /* buffer linked list */
  45 };
  46
  47 /*
  48  * Per-cpu relay channel buffer
  49  */
  50 struct rchan_buf {
  51         struct rchan *chan;             /* associated channel */
  52 //ust// wait_queue_head_t read_wait;    /* reader wait queue */
  53 //ust// struct timer_list timer;        /* reader wake-up timer */
  54 //ust// struct dentry *dentry;          /* channel file dentry */
  55         struct kref kref;               /* channel buffer refcount */
  56 //ust// struct list_head pages;         /* list of buffer pages */
  57         void *buf_data; //ust//
  58         size_t buf_size;
  59 //ust// struct buf_page *wpage;         /* current write page (cache) */
  60 //ust// struct buf_page *hpage[2];      /* current subbuf header page (cache) */
  61 //ust// struct buf_page *rpage;         /* current subbuf read page (cache) */
  62 //ust// unsigned int page_count;        /* number of current buffer pages */
  63         unsigned int finalized;         /* buffer has been finalized */
  64 //ust// unsigned int cpu;               /* this buf's cpu */
  65         int shmid;                      /* the shmid of the buffer data pages */
  66 } ____cacheline_aligned;
  67
  68 /*
  69  * Relay channel data structure
  70  */
  71 struct rchan {
  72         u32 version;                    /* the version of this struct */
  73         size_t subbuf_size;             /* sub-buffer size */
  74         size_t n_subbufs;               /* number of sub-buffers per buffer */
  75         size_t alloc_size;              /* total buffer size allocated */
  76         struct rchan_callbacks *cb;     /* client callbacks */
  77         struct kref kref;               /* channel refcount */
  78         void *private_data;             /* for user-defined data */
  79 //ust// struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
  80         struct rchan_buf *buf;
  81         struct list_head list;          /* for channel list */
  82         struct dentry *parent;          /* parent dentry passed to open */
  83         int subbuf_size_order;          /* order of sub-buffer size */
  84 //ust// char base_filename[NAME_MAX];   /* saved base filename */
  85 };
  86
  87 /*
  88  * Relay channel client callbacks
  89  */
  90 struct rchan_callbacks {
  91         /*
  92          * subbuf_start - called on buffer-switch to a new sub-buffer
  93          * @buf: the channel buffer containing the new sub-buffer
  94          * @subbuf: the start of the new sub-buffer
  95          * @prev_subbuf: the start of the previous sub-buffer
  96          * @prev_padding: unused space at the end of previous sub-buffer
  97          *
  98          * The client should return 1 to continue logging, 0 to stop
  99          * logging.
 100          *
 101          * NOTE: subbuf_start will also be invoked when the buffer is
 102          *       created, so that the first sub-buffer can be initialized
 103          *       if necessary.  In this case, prev_subbuf will be NULL.
 104          *
 105          * NOTE: the client can reserve bytes at the beginning of the new
 106          *       sub-buffer by calling subbuf_start_reserve() in this callback.
 107          */
 108         int (*subbuf_start) (struct rchan_buf *buf,
 109                              void *subbuf,
 110                              void *prev_subbuf,
 111                              size_t prev_padding);
 112
 113         /*
 114          * create_buf_file - create file to represent a relay channel buffer
 115          * @filename: the name of the file to create
 116          * @parent: the parent of the file to create
 117          * @mode: the mode of the file to create
 118          * @buf: the channel buffer
 119          *
 120          * Called during relay_open(), once for each per-cpu buffer,
 121          * to allow the client to create a file to be used to
 122          * represent the corresponding channel buffer.  If the file is
 123          * created outside of relay, the parent must also exist in
 124          * that filesystem.
 125          *
 126          * The callback should return the dentry of the file created
 127          * to represent the relay buffer.
 128          *
 129          * Setting the is_global outparam to a non-zero value will
 130          * cause relay_open() to create a single global buffer rather
 131          * than the default set of per-cpu buffers.
 132          *
 133          * See Documentation/filesystems/relayfs.txt for more info.
 134          */
 135         struct dentry *(*create_buf_file)(const char *filename,
 136                                           struct dentry *parent,
 137                                           int mode,
 138                                           struct rchan_buf *buf);
 139
 140         /*
 141          * remove_buf_file - remove file representing a relay channel buffer
 142          * @dentry: the dentry of the file to remove
 143          *
 144          * Called during relay_close(), once for each per-cpu buffer,
 145          * to allow the client to remove a file used to represent a
 146          * channel buffer.
 147          *
 148          * The callback should return 0 if successful, negative if not.
 149          */
 150 //ust// int (*remove_buf_file)(struct rchan_buf *buf);
 151 };
 152
 153 extern struct buf_page *ltt_relay_find_prev_page(struct rchan_buf *buf,
 154         struct buf_page *page, size_t offset, ssize_t diff_offset);
 155
 156 extern struct buf_page *ltt_relay_find_next_page(struct rchan_buf *buf,
 157         struct buf_page *page, size_t offset, ssize_t diff_offset);
 158
 159 extern void _ltt_relay_write(struct rchan_buf *buf, size_t offset,
 160         const void *src, size_t len, ssize_t cpy);
 161
 162 extern int ltt_relay_read(struct rchan_buf *buf, size_t offset,
 163         void *dest, size_t len);
 164
 165 extern struct buf_page *ltt_relay_read_get_page(struct rchan_buf *buf,
 166         size_t offset);
 167
 168 /*
 169  * Return the address where a given offset is located.
 170  * Should be used to get the current subbuffer header pointer. Given we know
 171  * it's never on a page boundary, it's safe to write directly to this address,
 172  * as long as the write is never bigger than a page size.
 173  */
 174 extern void *ltt_relay_offset_address(struct rchan_buf *buf,
 175         size_t offset);
 176
 177 /*
 178  * Find the page containing "offset". Cache it if it is after the currently
 179  * cached page.
 180  */
 181 static inline struct buf_page *ltt_relay_cache_page(struct rchan_buf *buf,
 182                 struct buf_page **page_cache,
 183                 struct buf_page *page, size_t offset)
 184 {
 185         ssize_t diff_offset;
 186         ssize_t half_buf_size = buf->chan->alloc_size >> 1;
 187
 188         /*
 189          * Make sure this is the page we want to write into. The current
 190          * page is changed concurrently by other writers. [wrh]page are
 191          * used as a cache remembering the last page written
 192          * to/read/looked up for header address. No synchronization;
 193          * could have to find the previous page is a nested write
 194          * occured. Finding the right page is done by comparing the
 195          * dest_offset with the buf_page offsets.
 196          * When at the exact opposite of the buffer, bias towards forward search
 197          * because it will be cached.
 198          */
 199
 200         diff_offset = (ssize_t)offset - (ssize_t)page->offset;
 201         if (diff_offset <= -(ssize_t)half_buf_size)
 202                 diff_offset += buf->chan->alloc_size;
 203         else if (diff_offset > half_buf_size)
 204                 diff_offset -= buf->chan->alloc_size;
 205
 206         if (unlikely(diff_offset >= (ssize_t)PAGE_SIZE)) {
 207                 page = ltt_relay_find_next_page(buf, page, offset, diff_offset);
 208                 *page_cache = page;
 209         } else if (unlikely(diff_offset < 0)) {
 210                 page = ltt_relay_find_prev_page(buf, page, offset, diff_offset);
 211         }
 212         return page;
 213 }
 214
 215 //ust// #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 216  static inline void ltt_relay_do_copy(void *dest, const void *src, size_t len)
 217 {
 218         switch (len) {
 219         case 0: break;
 220         case 1: *(u8 *)dest = *(const u8 *)src;
 221                 break;
 222         case 2: *(u16 *)dest = *(const u16 *)src;
 223                 break;
 224         case 4: *(u32 *)dest = *(const u32 *)src;
 225                 break;
 226 //ust// #if (BITS_PER_LONG == 64)
 227         case 8: *(u64 *)dest = *(const u64 *)src;
 228                 break;
 229 //ust// #endif
 230         default:
 231                 memcpy(dest, src, len);
 232         }
 233 }
 234 //ust// #else
 235 //ust// /*
 236 //ust//  * Returns whether the dest and src addresses are aligned on
 237 //ust//  * min(sizeof(void *), len). Call this with statically known len for efficiency.
 238 //ust//  */
 239 //ust// static inline int addr_aligned(const void *dest, const void *src, size_t len)
 240 //ust// {
 241 //ust//         if (ltt_align((size_t)dest, len))
 242 //ust//                 return 0;
 243 //ust//         if (ltt_align((size_t)src, len))
 244 //ust//                 return 0;
 245 //ust//         return 1;
 246 //ust// }
 247 //ust//
 248 //ust// static inline void ltt_relay_do_copy(void *dest, const void *src, size_t len)
 249 //ust// {
 250 //ust//         switch (len) {
 251 //ust//         case 0: break;
 252 //ust//         case 1: *(u8 *)dest = *(const u8 *)src;
 253 //ust//                 break;
 254 //ust//         case 2: if (unlikely(!addr_aligned(dest, src, 2)))
 255 //ust//                         goto memcpy_fallback;
 256 //ust//                 *(u16 *)dest = *(const u16 *)src;
 257 //ust//                 break;
 258 //ust//         case 4: if (unlikely(!addr_aligned(dest, src, 4)))
 259 //ust//                         goto memcpy_fallback;
 260 //ust//                 *(u32 *)dest = *(const u32 *)src;
 261 //ust//                 break;
 262 //ust// #if (BITS_PER_LONG == 64)
 263 //ust//         case 8: if (unlikely(!addr_aligned(dest, src, 8)))
 264 //ust//                         goto memcpy_fallback;
 265 //ust//                 *(u64 *)dest = *(const u64 *)src;
 266 //ust//                 break;
 267 //ust// #endif
 268 //ust//         default:
 269 //ust//                 goto memcpy_fallback;
 270 //ust//         }
 271 //ust//         return;
 272 //ust// memcpy_fallback:
 273 //ust//         memcpy(dest, src, len);
 274 //ust// }
 275 //ust// #endif
 276
 277 static inline int ltt_relay_write(struct rchan_buf *buf, size_t offset,
 278         const void *src, size_t len)
 279 {
 280 //ust// struct buf_page *page;
 281 //ust// ssize_t pagecpy;
 282 //ust//
 283 //ust// offset &= buf->chan->alloc_size - 1;
 284 //ust// page = buf->wpage;
 285 //ust//
 286 //ust// page = ltt_relay_cache_page(buf, &buf->wpage, page, offset);
 287 //ust// pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
 288 //ust// ltt_relay_do_copy(page_address(page->page)
 289 //ust//         + (offset & ~PAGE_MASK), src, pagecpy);
 290 //ust//
 291 //ust// if (unlikely(len != pagecpy))
 292 //ust//         _ltt_relay_write(buf, offset, src, len, page, pagecpy);
 293 //ust// return len;
 294
 295         size_t cpy;
 296         size_t buf_offset = BUFFER_OFFSET(offset, buf->chan);
 297
 298         assert(buf_offset < buf->chan->subbuf_size*buf->chan->n_subbufs);
 299
 300         cpy = min_t(size_t, len, buf->buf_size - buf_offset);
 301         ltt_relay_do_copy(buf->buf_data + buf_offset, src, cpy);
 302
 303         if (unlikely(len != cpy))
 304                 _ltt_relay_write(buf, buf_offset, src, len, cpy);
 305         return len;
 306 }
 307
 308 /*
 309  * CONFIG_LTT_RELAY kernel API, ltt/ltt-relay-alloc.c
 310  */
 311
 312 struct rchan *ltt_relay_open(const char *base_filename,
 313                          struct dentry *parent,
 314                          size_t subbuf_size,
 315                          size_t n_subbufs,
 316                          void *private_data);
 317 extern void ltt_relay_close(struct rchan *chan);
 318
 319 /*
 320  * exported ltt_relay file operations, ltt/ltt-relay-alloc.c
 321  */
 322 extern const struct file_operations ltt_relay_file_operations;
 323
 324
 325 /* LTTng lockless logging buffer info */
 326 struct ltt_channel_buf_struct {
 327         /* First 32 bytes cache-hot cacheline */
 328         local_t offset;                 /* Current offset in the buffer */
 329         local_t *commit_count;          /* Commit count per sub-buffer */
 330         atomic_long_t consumed;         /*
 331                                          * Current offset in the buffer
 332                                          * standard atomic access (shared)
 333                                          */
 334         unsigned long last_tsc;         /*
 335                                          * Last timestamp written in the buffer.
 336                                          */
 337         /* End of first 32 bytes cacheline */
 338 //ust// #ifdef CONFIG_LTT_VMCORE
 339 //ust// local_t *commit_seq;            /* Consecutive commits */
 340 //ust// #endif
 341         atomic_long_t active_readers;   /*
 342                                          * Active readers count
 343                                          * standard atomic access (shared)
 344                                          */
 345         local_t events_lost;
 346         local_t corrupted_subbuffers;
 347 //ust// spinlock_t full_lock;           /*
 348 //ust//                                  * buffer full condition spinlock, only
 349 //ust//                                  * for userspace tracing blocking mode
 350 //ust//                                  * synchronization with reader.
 351 //ust//                                  */
 352 //ust// wait_queue_head_t write_wait;   /*
 353 //ust//                                  * Wait queue for blocking user space
 354 //ust//                                  * writers
 355 //ust//                                  */
 356 //ust// atomic_t wakeup_readers;        /* Boolean : wakeup readers waiting ? */
 357         /* one byte is written to this pipe when data is available, in order
 358            to wake the consumer */
 359         /* portability: Single byte writes must be as quick as possible. The kernel-side
 360            buffer must be large enough so the writer doesn't block. From the pipe(7)
 361            man page: Since linux 2.6.11, the pipe capacity is 65536 bytes. */
 362         int data_ready_fd_write;
 363         /* the reading end of the pipe */
 364         int data_ready_fd_read;
 365
 366         /* commit count per subbuffer; must be at end of struct */
 367         local_t commit_seq[0] ____cacheline_aligned;
 368 } ____cacheline_aligned;
 369
 370 int ltt_do_get_subbuf(struct rchan_buf *buf, struct ltt_channel_buf_struct *ltt_buf, long *pconsumed_old);
 371
 372 int ltt_do_put_subbuf(struct rchan_buf *buf, struct ltt_channel_buf_struct *ltt_buf, u32 uconsumed_old);
 373
 374 #endif /* _LINUX_LTT_RELAY_H */