Add mutex for channel wakeup fd update

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

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 76f369e9bc7bbee03faf55627c254855ddf54f40..871d96d1c6e07848348cadbeb872d5a480214add 100644 (file)
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -112,6 +112,12 @@ struct switch_offsets {
 
 DEFINE_URCU_TLS(unsigned int, lib_ring_buffer_nesting);
 
+/*
+ * wakeup_fd_mutex protects wakeup fd use by timer from concurrent
+ * close.
+ */
+static pthread_mutex_t wakeup_fd_mutex = PTHREAD_MUTEX_INITIALIZER;
+
 static
 void lib_ring_buffer_print_errors(struct channel *chan,
                                struct lttng_ust_lib_ring_buffer *buf, int cpu,
@@ -301,6 +307,7 @@ void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 
        DBG("Timer for channel %p\n", chan);
 
+       pthread_mutex_lock(&wakeup_fd_mutex);
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
                for_each_possible_cpu(cpu) {
                        struct lttng_ust_lib_ring_buffer *buf =
@@ -316,6 +323,7 @@ void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
                        lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
                                chan->handle);
        }
+       pthread_mutex_unlock(&wakeup_fd_mutex);
        return;
 }
 
@@ -612,7 +620,6 @@ static void channel_print_errors(struct channel *chan,
 static void channel_free(struct channel *chan,
                struct lttng_ust_shm_handle *handle)
 {
-       channel_print_errors(chan, handle);
        channel_backend_free(&chan->backend, handle);
        /* chan is freed by shm teardown */
        shm_object_table_destroy(handle->table);
@@ -754,7 +761,8 @@ error_table_alloc:
 }
 
 struct lttng_ust_shm_handle *channel_handle_create(void *data,
-                                       uint64_t memory_map_size)
+                                       uint64_t memory_map_size,
+                                       int wakeup_fd)
 {
        struct lttng_ust_shm_handle *handle;
        struct shm_object *object;
@@ -769,7 +777,7 @@ struct lttng_ust_shm_handle *channel_handle_create(void *data,
                goto error_table_alloc;
        /* Add channel object */
        object = shm_object_table_append_mem(handle->table, data,
-                       memory_map_size);
+                       memory_map_size, wakeup_fd);
        if (!object)
                goto error_table_object;
        /* struct channel is at object 0, offset 0 (hardcoded) */
@@ -830,6 +838,10 @@ void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
                 * switching the buffers.
                 */
                channel_unregister_notifiers(chan, handle);
+               /*
+                * The consumer prints errors.
+                */
+               channel_print_errors(chan, handle);
        }
 
        /*
@@ -865,7 +877,27 @@ struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
        return shmp(handle, chan->backend.buf[cpu].shmp);
 }
 
-int ring_buffer_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+                       struct channel *chan,
+                       struct lttng_ust_shm_handle *handle)
+{
+       struct shm_ref *ref;
+
+       ref = &handle->chan._ref;
+       return shm_close_wait_fd(handle, ref);
+}
+
+int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+                       struct channel *chan,
+                       struct lttng_ust_shm_handle *handle)
+{
+       struct shm_ref *ref;
+
+       ref = &handle->chan._ref;
+       return shm_close_wakeup_fd(handle, ref);
+}
+
+int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
                        struct channel *chan,
                        struct lttng_ust_shm_handle *handle,
                        int cpu)
@@ -882,12 +914,13 @@ int ring_buffer_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *con
        return shm_close_wait_fd(handle, ref);
 }
 
-int ring_buffer_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
                        struct channel *chan,
                        struct lttng_ust_shm_handle *handle,
                        int cpu)
 {
        struct shm_ref *ref;
+       int ret;
 
        if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) {
                cpu = 0;
@@ -896,7 +929,10 @@ int ring_buffer_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *c
                        return -EINVAL;
        }
        ref = &chan->backend.buf[cpu].shmp._ref;
-       return shm_close_wakeup_fd(handle, ref);
+       pthread_mutex_lock(&wakeup_fd_mutex);
+       ret = shm_close_wakeup_fd(handle, ref);
+       pthread_mutex_unlock(&wakeup_fd_mutex);
+       return ret;
 }
 
 int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,