X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=libringbuffer%2Fring_buffer_frontend.c;h=84c6726e97a2d66ec612bc083aaa4ca36ab6225a;hb=0bf3c920174f81b8675984010785b8af9b9b1b59;hp=76f369e9bc7bbee03faf55627c254855ddf54f40;hpb=03d2d2938911e2641038313211b08546338953c3;p=lttng-ust.git

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 76f369e9..84c6726e 100644
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -80,8 +80,9 @@
 /* Print DBG() messages about events lost only every 1048576 hits */
 #define DBG_PRINT_NR_LOST	(1UL << 20)
 
-#define LTTNG_UST_RB_SIG		SIGRTMIN
-#define LTTNG_UST_RB_SIG_TEARDOWN	SIGRTMIN + 1
+#define LTTNG_UST_RB_SIG_FLUSH		SIGRTMIN
+#define LTTNG_UST_RB_SIG_READ		SIGRTMIN + 1
+#define LTTNG_UST_RB_SIG_TEARDOWN	SIGRTMIN + 2
 #define CLOCKID		CLOCK_MONOTONIC
 
 /*
@@ -106,12 +107,17 @@
 struct switch_offsets {
 	unsigned long begin, end, old;
 	size_t pre_header_padding, size;
-	unsigned int switch_new_start:1, switch_new_end:1, switch_old_start:1,
-		     switch_old_end:1;
+	unsigned int switch_new_start:1, switch_old_start:1, switch_old_end:1;
 };
 
 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,
@@ -121,15 +127,21 @@ void lib_ring_buffer_print_errors(struct channel *chan,
  * Handle timer teardown race wrt memory free of private data by
  * ring buffer signals are handled by a single thread, which permits
  * a synchronization point between handling of each signal.
- * Protected by the ust mutex.
+ * Protected by the lock within the structure.
  */
 struct timer_signal_data {
 	pthread_t tid;	/* thread id managing signals */
 	int setup_done;
 	int qs_done;
+	pthread_mutex_t lock;
 };
 
-static struct timer_signal_data timer_signal;
+static struct timer_signal_data timer_signal = {
+	.tid = 0,
+	.setup_done = 0,
+	.qs_done = 0,
+	.lock = PTHREAD_MUTEX_INITIALIZER,
+};
 
 /**
  * lib_ring_buffer_reset - Reset ring buffer to initial values.
@@ -262,29 +274,6 @@ free_chanbuf:
 	return ret;
 }
 
-#if 0
-static void switch_buffer_timer(unsigned long data)
-{
-	struct lttng_ust_lib_ring_buffer *buf = (struct lttng_ust_lib_ring_buffer *)data;
-	struct channel *chan = shmp(handle, buf->backend.chan);
-	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
-
-	/*
-	 * Only flush buffers periodically if readers are active.
-	 */
-	if (uatomic_read(&buf->active_readers))
-		lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, handle);
-
-	//TODO timers
-	//if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-	//	mod_timer_pinned(&buf->switch_timer,
-	//			 jiffies + chan->switch_timer_interval);
-	//else
-	//	mod_timer(&buf->switch_timer,
-	//		  jiffies + chan->switch_timer_interval);
-}
-#endif //0
-
 static
 void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 {
@@ -299,23 +288,79 @@ void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 	handle = chan->handle;
 	config = &chan->backend.config;
 
-	DBG("Timer for channel %p\n", chan);
+	DBG("Switch timer for channel %p\n", chan);
 
+	/*
+	 * Only flush buffers periodically if readers are active.
+	 */
+	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 =
 				shmp(handle, chan->backend.buf[cpu].shmp);
+			if (uatomic_read(&buf->active_readers))
+				lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
+					chan->handle);
+		}
+	} else {
+		struct lttng_ust_lib_ring_buffer *buf =
+			shmp(handle, chan->backend.buf[0].shmp);
 
+		if (uatomic_read(&buf->active_readers))
 			lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
 				chan->handle);
+	}
+	pthread_mutex_unlock(&wakeup_fd_mutex);
+	return;
+}
+
+static
+void lib_ring_buffer_channel_do_read(struct channel *chan)
+{
+	const struct lttng_ust_lib_ring_buffer_config *config;
+	struct lttng_ust_shm_handle *handle;
+	int cpu;
+
+	handle = chan->handle;
+	config = &chan->backend.config;
+
+	/*
+	 * Only flush buffers periodically if readers are active.
+	 */
+	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 =
+				shmp(handle, chan->backend.buf[cpu].shmp);
+
+			if (uatomic_read(&buf->active_readers)
+			    && lib_ring_buffer_poll_deliver(config, buf,
+					chan, handle)) {
+				lib_ring_buffer_wakeup(buf, handle);
+			}
 		}
 	} else {
 		struct lttng_ust_lib_ring_buffer *buf =
 			shmp(handle, chan->backend.buf[0].shmp);
 
-			lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
-				chan->handle);
+		if (uatomic_read(&buf->active_readers)
+		    && lib_ring_buffer_poll_deliver(config, buf,
+				chan, handle)) {
+			lib_ring_buffer_wakeup(buf, handle);
+		}
 	}
+	pthread_mutex_unlock(&wakeup_fd_mutex);
+}
+
+static
+void lib_ring_buffer_channel_read_timer(int sig, siginfo_t *si, void *uc)
+{
+	struct channel *chan;
+
+	assert(CMM_LOAD_SHARED(timer_signal.tid) == pthread_self());
+	chan = si->si_value.sival_ptr;
+	DBG("Read timer for channel %p\n", chan);
+	lib_ring_buffer_channel_do_read(chan);
 	return;
 }
 
@@ -328,7 +373,11 @@ void rb_setmask(sigset_t *mask)
 	if (ret) {
 		PERROR("sigemptyset");
 	}
-	ret = sigaddset(mask, LTTNG_UST_RB_SIG);
+	ret = sigaddset(mask, LTTNG_UST_RB_SIG_FLUSH);
+	if (ret) {
+		PERROR("sigaddset");
+	}
+	ret = sigaddset(mask, LTTNG_UST_RB_SIG_READ);
 	if (ret) {
 		PERROR("sigaddset");
 	}
@@ -352,12 +401,16 @@ void *sig_thread(void *arg)
 	for (;;) {
 		signr = sigwaitinfo(&mask, &info);
 		if (signr == -1) {
-			PERROR("sigwaitinfo");
+			if (errno != EINTR)
+				PERROR("sigwaitinfo");
 			continue;
 		}
-		if (signr == LTTNG_UST_RB_SIG) {
+		if (signr == LTTNG_UST_RB_SIG_FLUSH) {
 			lib_ring_buffer_channel_switch_timer(info.si_signo,
 					&info, NULL);
+		} else if (signr == LTTNG_UST_RB_SIG_READ) {
+			lib_ring_buffer_channel_read_timer(info.si_signo,
+					&info, NULL);
 		} else if (signr == LTTNG_UST_RB_SIG_TEARDOWN) {
 			cmm_smp_mb();
 			CMM_STORE_SHARED(timer_signal.qs_done, 1);
@@ -370,7 +423,6 @@ void *sig_thread(void *arg)
 }
 
 /*
- * Called with ust_lock() held.
  * Ensure only a single thread listens on the timer signal.
  */
 static
@@ -379,8 +431,9 @@ void lib_ring_buffer_setup_timer_thread(void)
 	pthread_t thread;
 	int ret;
 
+	pthread_mutex_lock(&timer_signal.lock);
 	if (timer_signal.setup_done)
-		return;
+		goto end;
 
 	ret = pthread_create(&thread, NULL, &sig_thread, NULL);
 	if (ret) {
@@ -393,11 +446,64 @@ void lib_ring_buffer_setup_timer_thread(void)
 		PERROR("pthread_detach");
 	}
 	timer_signal.setup_done = 1;
+end:
+	pthread_mutex_unlock(&timer_signal.lock);
 }
 
 /*
- * Called with ust_lock() held.
+ * Wait for signal-handling thread quiescent state.
  */
+static
+void lib_ring_buffer_wait_signal_thread_qs(unsigned int signr)
+{
+	sigset_t pending_set;
+	int ret;
+
+	/*
+	 * We need to be the only thread interacting with the thread
+	 * that manages signals for teardown synchronization.
+	 */
+	pthread_mutex_lock(&timer_signal.lock);
+
+	/*
+	 * Ensure we don't have any signal queued for this channel.
+	 */
+	for (;;) {
+		ret = sigemptyset(&pending_set);
+		if (ret == -1) {
+			PERROR("sigemptyset");
+		}
+		ret = sigpending(&pending_set);
+		if (ret == -1) {
+			PERROR("sigpending");
+		}
+		if (!sigismember(&pending_set, signr))
+			break;
+		caa_cpu_relax();
+	}
+
+	/*
+	 * From this point, no new signal handler will be fired that
+	 * would try to access "chan". However, we still need to wait
+	 * for any currently executing handler to complete.
+	 */
+	cmm_smp_mb();
+	CMM_STORE_SHARED(timer_signal.qs_done, 0);
+	cmm_smp_mb();
+
+	/*
+	 * Kill with LTTNG_UST_RB_SIG_TEARDOWN, so signal management
+	 * thread wakes up.
+	 */
+	kill(getpid(), LTTNG_UST_RB_SIG_TEARDOWN);
+
+	while (!CMM_LOAD_SHARED(timer_signal.qs_done))
+		caa_cpu_relax();
+	cmm_smp_mb();
+
+	pthread_mutex_unlock(&timer_signal.lock);
+}
+
 static
 void lib_ring_buffer_channel_switch_timer_start(struct channel *chan)
 {
@@ -413,7 +519,7 @@ void lib_ring_buffer_channel_switch_timer_start(struct channel *chan)
 	lib_ring_buffer_setup_timer_thread();
 
 	sev.sigev_notify = SIGEV_SIGNAL;
-	sev.sigev_signo = LTTNG_UST_RB_SIG;
+	sev.sigev_signo = LTTNG_UST_RB_SIG_FLUSH;
 	sev.sigev_value.sival_ptr = chan;
 	ret = timer_create(CLOCKID, &sev, &chan->switch_timer);
 	if (ret == -1) {
@@ -431,14 +537,10 @@ void lib_ring_buffer_channel_switch_timer_start(struct channel *chan)
 	}
 }
 
-/*
- * Called with ust_lock() held.
- */
 static
 void lib_ring_buffer_channel_switch_timer_stop(struct channel *chan)
 {
-	sigset_t pending_set;
-	int sig_is_pending, ret;
+	int ret;
 
 	if (!chan->switch_timer_interval || !chan->switch_timer_enabled)
 		return;
@@ -448,144 +550,79 @@ void lib_ring_buffer_channel_switch_timer_stop(struct channel *chan)
 		PERROR("timer_delete");
 	}
 
-	/*
-	 * Ensure we don't have any signal queued for this channel.
-	 */
-	for (;;) {
-		ret = sigemptyset(&pending_set);
-		if (ret == -1) {
-			PERROR("sigemptyset");
-		}
-		ret = sigpending(&pending_set);
-		if (ret == -1) {
-			PERROR("sigpending");
-		}
-		sig_is_pending = sigismember(&pending_set, LTTNG_UST_RB_SIG);
-		if (!sig_is_pending)
-			break;
-		caa_cpu_relax();
-	}
-
-	/*
-	 * From this point, no new signal handler will be fired that
-	 * would try to access "chan". However, we still need to wait
-	 * for any currently executing handler to complete.
-	 */
-	cmm_smp_mb();
-	CMM_STORE_SHARED(timer_signal.qs_done, 0);
-	cmm_smp_mb();
-
-	/*
-	 * Kill with LTTNG_UST_RB_SIG_TEARDOWN, so signal management
-	 * thread wakes up.
-	 */
-	kill(getpid(), LTTNG_UST_RB_SIG_TEARDOWN);
-
-	while (!CMM_LOAD_SHARED(timer_signal.qs_done))
-		caa_cpu_relax();
-	cmm_smp_mb();
+	lib_ring_buffer_wait_signal_thread_qs(LTTNG_UST_RB_SIG_FLUSH);
 
 	chan->switch_timer = 0;
 	chan->switch_timer_enabled = 0;
 }
 
-#if 0
-/*
- * Polling timer to check the channels for data.
- */
-static void read_buffer_timer(unsigned long data)
+static
+void lib_ring_buffer_channel_read_timer_start(struct channel *chan)
 {
-	struct lttng_ust_lib_ring_buffer *buf = (struct lttng_ust_lib_ring_buffer *)data;
-	struct channel *chan = shmp(handle, buf->backend.chan);
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
+	struct sigevent sev;
+	struct itimerspec its;
+	int ret;
 
-	CHAN_WARN_ON(chan, !buf->backend.allocated);
+	if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER
+			|| !chan->read_timer_interval || chan->read_timer_enabled)
+		return;
 
-	if (uatomic_read(&buf->active_readers))
-	    && lib_ring_buffer_poll_deliver(config, buf, chan)) {
-		//TODO
-		//wake_up_interruptible(&buf->read_wait);
-		//wake_up_interruptible(&chan->read_wait);
-	}
+	chan->read_timer_enabled = 1;
 
-	//TODO
-	//if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-	//	mod_timer_pinned(&buf->read_timer,
-	//			 jiffies + chan->read_timer_interval);
-	//else
-	//	mod_timer(&buf->read_timer,
-	//		  jiffies + chan->read_timer_interval);
-}
-#endif //0
+	lib_ring_buffer_setup_timer_thread();
 
-static void lib_ring_buffer_start_read_timer(struct lttng_ust_lib_ring_buffer *buf,
-			   struct lttng_ust_shm_handle *handle)
-{
-	struct channel *chan = shmp(handle, buf->backend.chan);
-	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
+	sev.sigev_notify = SIGEV_SIGNAL;
+	sev.sigev_signo = LTTNG_UST_RB_SIG_READ;
+	sev.sigev_value.sival_ptr = chan;
+	ret = timer_create(CLOCKID, &sev, &chan->read_timer);
+	if (ret == -1) {
+		PERROR("timer_create");
+	}
 
-	if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER
-	    || !chan->read_timer_interval
-	    || buf->read_timer_enabled)
-		return;
+	its.it_value.tv_sec = chan->read_timer_interval / 1000000;
+	its.it_value.tv_nsec = chan->read_timer_interval % 1000000;
+	its.it_interval.tv_sec = its.it_value.tv_sec;
+	its.it_interval.tv_nsec = its.it_value.tv_nsec;
 
-	//TODO
-	//init_timer(&buf->read_timer);
-	//buf->read_timer.function = read_buffer_timer;
-	//buf->read_timer.expires = jiffies + chan->read_timer_interval;
-	//buf->read_timer.data = (unsigned long)buf;
-
-	//if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-	//	add_timer_on(&buf->read_timer, buf->backend.cpu);
-	//else
-	//	add_timer(&buf->read_timer);
-	buf->read_timer_enabled = 1;
+	ret = timer_settime(chan->read_timer, 0, &its, NULL);
+	if (ret == -1) {
+		PERROR("timer_settime");
+	}
 }
 
-static void lib_ring_buffer_stop_read_timer(struct lttng_ust_lib_ring_buffer *buf,
-			   struct lttng_ust_shm_handle *handle)
+static
+void lib_ring_buffer_channel_read_timer_stop(struct channel *chan)
 {
-	struct channel *chan = shmp(handle, buf->backend.chan);
 	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
+	int ret;
 
 	if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER
-	    || !chan->read_timer_interval
-	    || !buf->read_timer_enabled)
+			|| !chan->read_timer_interval || !chan->read_timer_enabled)
 		return;
 
-	//TODO
-	//del_timer_sync(&buf->read_timer);
+	ret = timer_delete(chan->read_timer);
+	if (ret == -1) {
+		PERROR("timer_delete");
+	}
+
 	/*
 	 * do one more check to catch data that has been written in the last
 	 * timer period.
 	 */
-	if (lib_ring_buffer_poll_deliver(config, buf, chan, handle)) {
-		//TODO
-		//wake_up_interruptible(&buf->read_wait);
-		//wake_up_interruptible(&chan->read_wait);
-	}
-	buf->read_timer_enabled = 0;
+	lib_ring_buffer_channel_do_read(chan);
+
+	lib_ring_buffer_wait_signal_thread_qs(LTTNG_UST_RB_SIG_READ);
+
+	chan->read_timer = 0;
+	chan->read_timer_enabled = 0;
 }
 
 static void channel_unregister_notifiers(struct channel *chan,
 			   struct lttng_ust_shm_handle *handle)
 {
-	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
-	int cpu;
-
 	lib_ring_buffer_channel_switch_timer_stop(chan);
-	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-		for_each_possible_cpu(cpu) {
-			struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[cpu].shmp);
-
-			lib_ring_buffer_stop_read_timer(buf, handle);
-		}
-	} else {
-		struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[0].shmp);
-
-		lib_ring_buffer_stop_read_timer(buf, handle);
-	}
-	//channel_backend_unregister_notifiers(&chan->backend);
+	lib_ring_buffer_channel_read_timer_stop(chan);
 }
 
 static void channel_print_errors(struct channel *chan,
@@ -612,7 +649,6 @@ 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);
@@ -649,7 +685,7 @@ struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buff
 		   size_t num_subbuf, unsigned int switch_timer_interval,
 		   unsigned int read_timer_interval)
 {
-	int ret, cpu;
+	int ret;
 	size_t shmsize, chansize;
 	struct channel *chan;
 	struct lttng_ust_shm_handle *handle;
@@ -720,29 +756,12 @@ struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buff
 
 	chan->handle = handle;
 	chan->commit_count_mask = (~0UL >> chan->backend.num_subbuf_order);
-	chan->switch_timer_interval = switch_timer_interval;
-
-	//TODO
-	//chan->read_timer_interval = read_timer_interval;
-	//init_waitqueue_head(&chan->read_wait);
-	//init_waitqueue_head(&chan->hp_wait);
 
+	chan->switch_timer_interval = switch_timer_interval;
+	chan->read_timer_interval = read_timer_interval;
 	lib_ring_buffer_channel_switch_timer_start(chan);
-	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
-		/*
-		 * In case of non-hotplug cpu, if the ring-buffer is allocated
-		 * in early initcall, it will not be notified of secondary cpus.
-		 * In that off case, we need to allocate for all possible cpus.
-		 */
-		for_each_possible_cpu(cpu) {
-			struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[cpu].shmp);
-			lib_ring_buffer_start_read_timer(buf, handle);
-		}
-	} else {
-		struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[0].shmp);
+	lib_ring_buffer_channel_read_timer_start(chan);
 
-		lib_ring_buffer_start_read_timer(buf, handle);
-	}
 	return handle;
 
 error_backend_init:
@@ -754,7 +773,8 @@ 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 +789,7 @@ 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 +850,10 @@ 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 +889,27 @@ 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 +926,13 @@ 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 +941,10 @@ 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,
@@ -978,7 +1026,7 @@ nodata:
 }
 
 /**
- * lib_ring_buffer_put_snapshot - move consumed counter forward
+ * lib_ring_buffer_move_consumer - move consumed counter forward
  * @buf: ring buffer
  * @consumed_new: new consumed count value
  */
@@ -1366,42 +1414,6 @@ void lib_ring_buffer_switch_new_start(struct lttng_ust_lib_ring_buffer *buf,
 					     handle);
 }
 
-/*
- * lib_ring_buffer_switch_new_end: finish switching current subbuffer
- *
- * The only remaining threads could be the ones with pending commits. They will
- * have to do the deliver themselves.
- */
-static
-void lib_ring_buffer_switch_new_end(struct lttng_ust_lib_ring_buffer *buf,
-				    struct channel *chan,
-				    struct switch_offsets *offsets,
-				    uint64_t tsc,
-				    struct lttng_ust_shm_handle *handle)
-{
-	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
-	unsigned long endidx = subbuf_index(offsets->end - 1, chan);
-	unsigned long commit_count, padding_size, data_size;
-
-	data_size = subbuf_offset(offsets->end - 1, chan) + 1;
-	padding_size = chan->backend.subbuf_size - data_size;
-	subbuffer_set_data_size(config, &buf->backend, endidx, data_size,
-				handle);
-
-	/*
-	 * Order all writes to buffer before the commit count update that will
-	 * determine that the subbuffer is full.
-	 */
-	cmm_smp_wmb();
-	v_add(config, padding_size, &shmp_index(handle, buf->commit_hot, endidx)->cc);
-	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, endidx)->cc);
-	lib_ring_buffer_check_deliver(config, buf, chan, offsets->end - 1,
-				  commit_count, endidx, handle);
-	lib_ring_buffer_write_commit_counter(config, buf, chan, endidx,
-					     offsets->end, commit_count,
-					     padding_size, handle);
-}
-
 /*
  * Returns :
  * 0 if ok
@@ -1554,7 +1566,6 @@ int lib_ring_buffer_try_reserve_slow(struct lttng_ust_lib_ring_buffer *buf,
 	offsets->begin = v_read(config, &buf->offset);
 	offsets->old = offsets->begin;
 	offsets->switch_new_start = 0;
-	offsets->switch_new_end = 0;
 	offsets->switch_old_end = 0;
 	offsets->pre_header_padding = 0;
 
@@ -1686,14 +1697,6 @@ int lib_ring_buffer_try_reserve_slow(struct lttng_ust_lib_ring_buffer *buf,
 		 */
 	}
 	offsets->end = offsets->begin + offsets->size;
-
-	if (caa_unlikely(subbuf_offset(offsets->end, chan) == 0)) {
-		/*
-		 * The offset_end will fall at the very beginning of the next
-		 * subbuffer.
-		 */
-		offsets->switch_new_end = 1;	/* For offsets->begin */
-	}
 	return 0;
 }
 
@@ -1767,9 +1770,6 @@ int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 	if (caa_unlikely(offsets.switch_new_start))
 		lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc, handle);
 
-	if (caa_unlikely(offsets.switch_new_end))
-		lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc, handle);
-
 	ctx->slot_size = offsets.size;
 	ctx->pre_offset = offsets.begin;
 	ctx->buf_offset = offsets.begin + offsets.pre_header_padding;