Fix fork handling, where child shares shm with parent

[lttng-ust.git] / libringbuffer / ring_buffer_frontend.c

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 6de8336861e4dadc43d77cf4f77140c54f67f64f..53d269d29644d9ef5578848f702099951b8fbd6a 100644 (file)
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -83,26 +83,15 @@ struct switch_offsets {
 
 __thread unsigned int lib_ring_buffer_nesting;
 
+/*
+ * TODO: this is unused. Errors are saved within the ring buffer.
+ * Eventually, allow consumerd to print these errors.
+ */
 static
 void lib_ring_buffer_print_errors(struct channel *chan,
                                  struct lttng_ust_lib_ring_buffer *buf, int cpu,
                                  struct lttng_ust_shm_handle *handle);
 
-/*
- * Must be called under cpu hotplug protection.
- */
-void lib_ring_buffer_free(struct lttng_ust_lib_ring_buffer *buf,
-                         struct lttng_ust_shm_handle *handle)
-{
-       struct channel *chan = shmp(handle, buf->backend.chan);
-
-       lib_ring_buffer_print_errors(chan, buf, buf->backend.cpu, handle);
-       /* buf->commit_hot will be freed by shm teardown */
-       /* buf->commit_cold will be freed by shm teardown */
-
-       lib_ring_buffer_backend_free(&buf->backend);
-}
-
 /**
  * lib_ring_buffer_reset - Reset ring buffer to initial values.
  * @buf: Ring buffer.
@@ -175,7 +164,6 @@ int lib_ring_buffer_create(struct lttng_ust_lib_ring_buffer *buf,
        const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
        struct channel *chan = caa_container_of(chanb, struct channel, backend);
        void *priv = channel_get_private(chan);
-       unsigned int num_subbuf;
        size_t subbuf_header_size;
        u64 tsc;
        int ret;
@@ -207,9 +195,6 @@ int lib_ring_buffer_create(struct lttng_ust_lib_ring_buffer *buf,
                goto free_commit;
        }
 
-       num_subbuf = chan->backend.num_subbuf;
-       //init_waitqueue_head(&buf->read_wait);
-
        /*
         * Write the subbuffer header for first subbuffer so we know the total
         * duration of data gathering.
@@ -235,7 +220,6 @@ free_init:
 free_commit:
        /* commit_hot will be freed by shm teardown */
 free_chanbuf:
-       lib_ring_buffer_backend_free(&buf->backend);
        return ret;
 }
 
@@ -600,9 +584,6 @@ void channel_release(struct channel *chan, struct lttng_ust_shm_handle *handle,
 void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
                int shadow)
 {
-       const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
-       int cpu;
-
        if (shadow) {
                channel_release(chan, handle, shadow);
                return;
@@ -610,42 +591,11 @@ void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
 
        channel_unregister_notifiers(chan, handle);
 
-       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-               for_each_channel_cpu(cpu, chan) {
-                       struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[cpu].shmp);
-
-                       if (config->cb.buffer_finalize)
-                               config->cb.buffer_finalize(buf,
-                                                          channel_get_private(chan),
-                                                          cpu, handle);
-                       if (buf->backend.allocated)
-                               lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH,
-                                               handle);
-                       /*
-                        * Perform flush before writing to finalized.
-                        */
-                       cmm_smp_wmb();
-                       CMM_ACCESS_ONCE(buf->finalized) = 1;
-                       //wake_up_interruptible(&buf->read_wait);
-               }
-       } else {
-               struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[0].shmp);
+       /*
+        * Note: the consumer takes care of finalizing and switching the
+        * buffers.
+        */
 
-               if (config->cb.buffer_finalize)
-                       config->cb.buffer_finalize(buf, channel_get_private(chan), -1, handle);
-               if (buf->backend.allocated)
-                       lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH,
-                                               handle);
-               /*
-                * Perform flush before writing to finalized.
-                */
-               cmm_smp_wmb();
-               CMM_ACCESS_ONCE(buf->finalized) = 1;
-               //wake_up_interruptible(&buf->read_wait);
-       }
-       CMM_ACCESS_ONCE(chan->finalized) = 1;
-       //wake_up_interruptible(&chan->hp_wait);
-       //wake_up_interruptible(&chan->read_wait);
        /*
         * sessiond/consumer are keeping a reference on the shm file
         * descriptor directly. No need to refcount.
@@ -973,7 +923,7 @@ void lib_ring_buffer_print_subbuffer_errors(struct lttng_ust_lib_ring_buffer *bu
        commit_count_sb = v_read(config, &shmp_index(handle, buf->commit_cold, cons_idx)->cc_sb);
 
        if (subbuf_offset(commit_count, chan) != 0)
-               ERRMSG("ring buffer %s, cpu %d: "
+               DBG("ring buffer %s, cpu %d: "
                       "commit count in subbuffer %lu,\n"
                       "expecting multiples of %lu bytes\n"
                       "  [ %lu bytes committed, %lu bytes reader-visible ]\n",
@@ -981,7 +931,7 @@ void lib_ring_buffer_print_subbuffer_errors(struct lttng_ust_lib_ring_buffer *bu
                       chan->backend.subbuf_size,
                       commit_count, commit_count_sb);
 
-       ERRMSG("ring buffer: %s, cpu %d: %lu bytes committed\n",
+       DBG("ring buffer: %s, cpu %d: %lu bytes committed\n",
               chan->backend.name, cpu, commit_count);
 }
 
@@ -1008,7 +958,7 @@ void lib_ring_buffer_print_buffer_errors(struct lttng_ust_lib_ring_buffer *buf,
        write_offset = v_read(config, &buf->offset);
        cons_offset = uatomic_read(&buf->consumed);
        if (write_offset != cons_offset)
-               ERRMSG("ring buffer %s, cpu %d: "
+               DBG("ring buffer %s, cpu %d: "
                       "non-consumed data\n"
                       "  [ %lu bytes written, %lu bytes read ]\n",
                       chan->backend.name, cpu, write_offset, cons_offset);
@@ -1030,7 +980,7 @@ void lib_ring_buffer_print_errors(struct channel *chan,
        const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
        void *priv = channel_get_private(chan);
 
-       ERRMSG("ring buffer %s, cpu %d: %lu records written, "
+       DBG("ring buffer %s, cpu %d: %lu records written, "
                          "%lu records overrun\n",
                          chan->backend.name, cpu,
                          v_read(config, &buf->records_count),
@@ -1039,7 +989,7 @@ void lib_ring_buffer_print_errors(struct channel *chan,
        if (v_read(config, &buf->records_lost_full)
            || v_read(config, &buf->records_lost_wrap)
            || v_read(config, &buf->records_lost_big))
-               ERRMSG("ring buffer %s, cpu %d: records were lost. Caused by:\n"
+               DBG("ring buffer %s, cpu %d: records were lost. Caused by:\n"
                       "  [ %lu buffer full, %lu nest buffer wrap-around, "
                       "%lu event too big ]\n",
                       chan->backend.name, cpu,