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 f8c106c6eb12f372f723e98668fdd10cd3bce625..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.
@@ -231,7 +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;
 }
 
@@ -596,9 +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;
@@ -606,42 +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.