Fix: handle writes of length 0
[lttng-ust.git] / libringbuffer / ring_buffer_backend.c
index cac746c246109d792432ad552e51cc77dd916356..3db1f860f3918d8a1e61a959e1f4501678f93687 100644 (file)
@@ -1,16 +1,29 @@
 /*
  * ring_buffer_backend.c
  *
- * Copyright (C) 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#define _GNU_SOURCE
 #include <urcu/arch.h>
+#include <limits.h>
 
-#include "ust/core.h"
-
-#include <ust/ringbuffer-config.h>
+#include <lttng/ringbuffer-config.h>
+#include "vatomic.h"
 #include "backend.h"
 #include "frontend.h"
 #include "smp.h"
  * @extra_reader_sb: need extra subbuffer for reader
  */
 static
-int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config,
-                                    struct lib_ring_buffer_backend *bufb,
+int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_config *config,
+                                    struct lttng_ust_lib_ring_buffer_backend *bufb,
                                     size_t size, size_t num_subbuf,
                                     int extra_reader_sb,
-                                    struct shm_handle *handle,
+                                    struct lttng_ust_shm_handle *handle,
                                     struct shm_object *shmobj)
 {
        struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend;
@@ -43,10 +56,10 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
        if (extra_reader_sb)
                num_subbuf_alloc++;
 
-       align_shm(shmobj, __alignof__(struct lib_ring_buffer_backend_pages_shmp));
+       align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
        set_shmp(bufb->array, zalloc_shm(shmobj,
-                       sizeof(struct lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc));
-       if (unlikely(!shmp(handle, bufb->array)))
+                       sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc));
+       if (caa_unlikely(!shmp(handle, bufb->array)))
                goto array_error;
 
        /*
@@ -56,25 +69,25 @@ int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config
        align_shm(shmobj, PAGE_SIZE);
        set_shmp(bufb->memory_map, zalloc_shm(shmobj,
                        subbuf_size * num_subbuf_alloc));
-       if (unlikely(!shmp(handle, bufb->memory_map)))
+       if (caa_unlikely(!shmp(handle, bufb->memory_map)))
                goto memory_map_error;
 
        /* Allocate backend pages array elements */
        for (i = 0; i < num_subbuf_alloc; i++) {
-               align_shm(shmobj, __alignof__(struct lib_ring_buffer_backend_pages));
-               set_shmp(shmp(handle, bufb->array)[i].shmp,
+               align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages));
+               set_shmp(shmp_index(handle, bufb->array, i)->shmp,
                        zalloc_shm(shmobj,
-                               sizeof(struct lib_ring_buffer_backend_pages)));
+                               sizeof(struct lttng_ust_lib_ring_buffer_backend_pages)));
                if (!shmp(handle, shmp_index(handle, bufb->array, i)->shmp))
                        goto free_array;
        }
 
        /* Allocate write-side subbuffer table */
-       align_shm(shmobj, __alignof__(struct lib_ring_buffer_backend_subbuffer));
+       align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
        set_shmp(bufb->buf_wsb, zalloc_shm(shmobj,
-                               sizeof(struct lib_ring_buffer_backend_subbuffer)
+                               sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer)
                                * num_subbuf));
-       if (unlikely(!shmp(handle, bufb->buf_wsb)))
+       if (caa_unlikely(!shmp(handle, bufb->buf_wsb)))
                goto free_array;
 
        for (i = 0; i < num_subbuf; i++)
@@ -113,12 +126,12 @@ array_error:
        return -ENOMEM;
 }
 
-int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb,
+int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb,
                                   struct channel_backend *chanb, int cpu,
-                                  struct shm_handle *handle,
+                                  struct lttng_ust_shm_handle *handle,
                                   struct shm_object *shmobj)
 {
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
 
        set_shmp(bufb->chan, handle->chan._ref);
        bufb->cpu = cpu;
@@ -129,19 +142,11 @@ int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb,
                                                handle, shmobj);
 }
 
-void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb)
-{
-       /* bufb->buf_wsb will be freed by shm teardown */
-       /* bufb->array[i] will be freed by shm teardown */
-       /* bufb->array will be freed by shm teardown */
-       bufb->allocated = 0;
-}
-
-void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb,
-                                  struct shm_handle *handle)
+void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb,
+                                  struct lttng_ust_shm_handle *handle)
 {
        struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
        unsigned long num_subbuf_alloc;
        unsigned int i;
 
@@ -175,7 +180,7 @@ void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb,
 void channel_backend_reset(struct channel_backend *chanb)
 {
        struct channel *chan = caa_container_of(chanb, struct channel, backend);
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
 
        /*
         * Don't reset buf_size, subbuf_size, subbuf_size_order,
@@ -190,11 +195,10 @@ void channel_backend_reset(struct channel_backend *chanb)
  * @chanb: channel backend
  * @name: channel name
  * @config: client ring buffer configuration
- * @priv: client private data
  * @parent: dentry of parent directory, %NULL for root directory
  * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
  * @num_subbuf: number of sub-buffers (power of 2)
- * @shm_handle: shared memory handle
+ * @lttng_ust_shm_handle: shared memory handle
  *
  * Returns channel pointer if successful, %NULL otherwise.
  *
@@ -206,36 +210,35 @@ void channel_backend_reset(struct channel_backend *chanb)
  */
 int channel_backend_init(struct channel_backend *chanb,
                         const char *name,
-                        const struct lib_ring_buffer_config *config,
-                        void *priv, size_t subbuf_size, size_t num_subbuf,
-                        struct shm_handle *handle)
+                        const struct lttng_ust_lib_ring_buffer_config *config,
+                        size_t subbuf_size, size_t num_subbuf,
+                        struct lttng_ust_shm_handle *handle)
 {
        struct channel *chan = caa_container_of(chanb, struct channel, backend);
        unsigned int i;
        int ret;
-       size_t shmsize = 0, bufshmsize = 0, num_subbuf_alloc;
+       size_t shmsize = 0, num_subbuf_alloc;
 
        if (!name)
                return -EPERM;
 
-       if (!(subbuf_size && num_subbuf))
-               return -EPERM;
-
        /* Check that the subbuffer size is larger than a page. */
        if (subbuf_size < PAGE_SIZE)
                return -EINVAL;
 
        /*
-        * Make sure the number of subbuffers and subbuffer size are power of 2.
+        * Make sure the number of subbuffers and subbuffer size are
+        * power of 2, and nonzero.
         */
-       CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1);
-       CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1);
+       if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
+               return -EINVAL;
+       if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
+               return -EINVAL;
 
        ret = subbuffer_id_check_index(config, num_subbuf);
        if (ret)
                return ret;
 
-       chanb->priv = priv;
        chanb->buf_size = num_subbuf * subbuf_size;
        chanb->subbuf_size = subbuf_size;
        chanb->buf_size_order = get_count_order(chanb->buf_size);
@@ -246,23 +249,23 @@ int channel_backend_init(struct channel_backend *chanb,
        chanb->num_subbuf = num_subbuf;
        strncpy(chanb->name, name, NAME_MAX);
        chanb->name[NAME_MAX - 1] = '\0';
-       chanb->config = config;
+       memcpy(&chanb->config, config, sizeof(*config));
 
        /* Per-cpu buffer size: control (prior to backend) */
-       shmsize = offset_align(shmsize, __alignof__(struct lib_ring_buffer));
-       shmsize += sizeof(struct lib_ring_buffer);
+       shmsize = offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer));
+       shmsize += sizeof(struct lttng_ust_lib_ring_buffer);
 
        /* Per-cpu buffer size: backend */
        /* num_subbuf + 1 is the worse case */
        num_subbuf_alloc = num_subbuf + 1;
-       shmsize += offset_align(shmsize, __alignof__(struct lib_ring_buffer_backend_pages_shmp));
-       shmsize += sizeof(struct lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc;
-       shmsize += offset_align(bufshmsize, PAGE_SIZE);
+       shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
+       shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc;
+       shmsize += offset_align(shmsize, PAGE_SIZE);
        shmsize += subbuf_size * num_subbuf_alloc;
-       shmsize += offset_align(bufshmsize, __alignof__(struct lib_ring_buffer_backend_pages));
-       shmsize += sizeof(struct lib_ring_buffer_backend_pages) * num_subbuf_alloc;
-       shmsize += offset_align(bufshmsize, __alignof__(struct lib_ring_buffer_backend_subbuffer));
-       shmsize += sizeof(struct lib_ring_buffer_backend_subbuffer) * num_subbuf;
+       shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages));
+       shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages) * num_subbuf_alloc;
+       shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
+       shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) * num_subbuf;
        /* Per-cpu buffer size: control (after backend) */
        shmsize += offset_align(shmsize, __alignof__(struct commit_counters_hot));
        shmsize += sizeof(struct commit_counters_hot) * num_subbuf;
@@ -270,18 +273,19 @@ int channel_backend_init(struct channel_backend *chanb,
        shmsize += sizeof(struct commit_counters_cold) * num_subbuf;
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-               struct lib_ring_buffer *buf;
+               struct lttng_ust_lib_ring_buffer *buf;
                /*
                 * We need to allocate for all possible cpus.
                 */
                for_each_possible_cpu(i) {
                        struct shm_object *shmobj;
 
-                       shmobj = shm_object_table_append(handle->table, shmsize);
+                       shmobj = shm_object_table_alloc(handle->table, shmsize,
+                                       SHM_OBJECT_SHM);
                        if (!shmobj)
                                goto end;
-                       align_shm(shmobj, __alignof__(struct lib_ring_buffer));
-                       set_shmp(chanb->buf[i].shmp, zalloc_shm(shmobj, sizeof(struct lib_ring_buffer)));
+                       align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer));
+                       set_shmp(chanb->buf[i].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer)));
                        buf = shmp(handle, chanb->buf[i].shmp);
                        if (!buf)
                                goto end;
@@ -293,16 +297,18 @@ int channel_backend_init(struct channel_backend *chanb,
                }
        } else {
                struct shm_object *shmobj;
-               struct lib_ring_buffer *buf;
+               struct lttng_ust_lib_ring_buffer *buf;
 
-               shmobj = shm_object_table_append(handle->table, shmsize);
+               shmobj = shm_object_table_alloc(handle->table, shmsize,
+                                       SHM_OBJECT_SHM);
                if (!shmobj)
                        goto end;
-               align_shm(shmobj, __alignof__(struct lib_ring_buffer));
-               set_shmp(chanb->buf[0].shmp, zalloc_shm(shmobj, sizeof(struct lib_ring_buffer)));
+               align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer));
+               set_shmp(chanb->buf[0].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer)));
                buf = shmp(handle, chanb->buf[0].shmp);
                if (!buf)
                        goto end;
+               set_shmp(buf->self, chanb->buf[0].shmp._ref);
                ret = lib_ring_buffer_create(buf, chanb, -1,
                                        handle, shmobj);
                if (ret)
@@ -313,15 +319,6 @@ int channel_backend_init(struct channel_backend *chanb,
        return 0;
 
 free_bufs:
-       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-               for_each_possible_cpu(i) {
-                       struct lib_ring_buffer *buf = shmp(handle, chanb->buf[i].shmp);
-
-                       if (!buf->backend.allocated)
-                               continue;
-                       lib_ring_buffer_free(buf, handle);
-               }
-       }
        /* We only free the buffer data upon shm teardown */
 end:
        return -ENOMEM;
@@ -334,26 +331,9 @@ end:
  * Destroy all channel buffers and frees the channel.
  */
 void channel_backend_free(struct channel_backend *chanb,
-                         struct shm_handle *handle)
+                         struct lttng_ust_shm_handle *handle)
 {
-       const struct lib_ring_buffer_config *config = chanb->config;
-       unsigned int i;
-
-       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-               for_each_possible_cpu(i) {
-                       struct lib_ring_buffer *buf = shmp(handle, chanb->buf[i].shmp);
-
-                       if (!buf->backend.allocated)
-                               continue;
-                       lib_ring_buffer_free(buf, handle);
-               }
-       } else {
-               struct lib_ring_buffer *buf = shmp(handle, chanb->buf[0].shmp);
-
-               CHAN_WARN_ON(chanb, !buf->backend.allocated);
-               lib_ring_buffer_free(buf, handle);
-       }
-       /* We only free the buffer data upon shm teardown */
+       /* SHM teardown takes care of everything */
 }
 
 /**
@@ -366,19 +346,19 @@ void channel_backend_free(struct channel_backend *chanb,
  * Should be protected by get_subbuf/put_subbuf.
  * Returns the length copied.
  */
-size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset,
-                           void *dest, size_t len, struct shm_handle *handle)
+size_t lib_ring_buffer_read(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset,
+                           void *dest, size_t len, struct lttng_ust_shm_handle *handle)
 {
        struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
        ssize_t orig_len;
-       struct lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
        unsigned long sb_bindex, id;
 
        orig_len = len;
        offset &= chanb->buf_size - 1;
 
-       if (unlikely(!len))
+       if (caa_unlikely(!len))
                return 0;
        id = bufb->buf_rsb.id;
        sb_bindex = subbuffer_id_get_index(config, id);
@@ -390,7 +370,7 @@ size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset,
        CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
        CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
                     && subbuffer_id_is_noref(config, id));
-       memcpy(dest, shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & ~(chanb->subbuf_size - 1)), len);
+       memcpy(dest, shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)), len);
        return orig_len;
 }
 
@@ -401,19 +381,22 @@ size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset,
  * @dest : destination address
  * @len : destination's length
  *
- * return string's length
+ * Return string's length, or -EINVAL on error.
  * Should be protected by get_subbuf/put_subbuf.
+ * Destination length should be at least 1 to hold '\0'.
  */
-int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offset,
-                             void *dest, size_t len, struct shm_handle *handle)
+int lib_ring_buffer_read_cstr(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset,
+                             void *dest, size_t len, struct lttng_ust_shm_handle *handle)
 {
        struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
        ssize_t string_len, orig_offset;
        char *str;
-       struct lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
        unsigned long sb_bindex, id;
 
+       if (caa_unlikely(!len))
+               return -EINVAL;
        offset &= chanb->buf_size - 1;
        orig_offset = offset;
        id = bufb->buf_rsb.id;
@@ -426,7 +409,7 @@ int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offse
        CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
        CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
                     && subbuffer_id_is_noref(config, id));
-       str = shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & ~(chanb->subbuf_size - 1));
+       str = shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1));
        string_len = strnlen(str, len);
        if (dest && len) {
                memcpy(dest, str, string_len);
@@ -445,13 +428,13 @@ int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offse
  * 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 *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb,
+void *lib_ring_buffer_read_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb,
                                          size_t offset,
-                                         struct shm_handle *handle)
+                                         struct lttng_ust_shm_handle *handle)
 {
-       struct lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
        struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
        unsigned long sb_bindex, id;
 
        offset &= chanb->buf_size - 1;
@@ -460,7 +443,7 @@ void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb,
        rpages = shmp_index(handle, bufb->array, sb_bindex);
        CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
                     && subbuffer_id_is_noref(config, id));
-       return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & ~(chanb->subbuf_size - 1));
+       return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1));
 }
 
 /**
@@ -473,14 +456,14 @@ void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb,
  * it's always at the beginning of a page, it's safe to write directly to this
  * address, as long as the write is never bigger than a page size.
  */
-void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb,
+void *lib_ring_buffer_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb,
                                     size_t offset,
-                                    struct shm_handle *handle)
+                                    struct lttng_ust_shm_handle *handle)
 {
        size_t sbidx;
-       struct lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
        struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend;
-       const struct lib_ring_buffer_config *config = chanb->config;
+       const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
        unsigned long sb_bindex, id;
 
        offset &= chanb->buf_size - 1;
@@ -490,5 +473,5 @@ void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb,
        rpages = shmp_index(handle, bufb->array, sb_bindex);
        CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
                     && subbuffer_id_is_noref(config, id));
-       return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & ~(chanb->subbuf_size - 1));
+       return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1));
 }
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