SoW-2019-0002: Dynamic Snapshot

[deliverable/lttng-modules.git] / lib / ringbuffer / ring_buffer_frontend.c

diff --git a/lib/ringbuffer/ring_buffer_frontend.c b/lib/ringbuffer/ring_buffer_frontend.c
index 3cab365264e87431530c449648b8a9d6314449e4..37786150af299c9436f94936c82f0bbbc4c7af33 100644 (file)
--- a/lib/ringbuffer/ring_buffer_frontend.c
+++ b/lib/ringbuffer/ring_buffer_frontend.c
@@ -133,6 +133,8 @@ void lib_ring_buffer_free(struct lib_ring_buffer *buf)
 {
        struct channel *chan = buf->backend.chan;
 
+       irq_work_sync(&buf->wakeup_pending);
+
        lib_ring_buffer_print_errors(chan, buf, buf->backend.cpu);
        lttng_kvfree(buf->commit_hot);
        lttng_kvfree(buf->commit_cold);
@@ -206,6 +208,19 @@ void channel_reset(struct channel *chan)
 }
 EXPORT_SYMBOL_GPL(channel_reset);
 
+static void lib_ring_buffer_pending_wakeup_buf(struct irq_work *entry)
+{
+       struct lib_ring_buffer *buf = container_of(entry, struct lib_ring_buffer,
+                                                  wakeup_pending);
+       wake_up_interruptible(&buf->read_wait);
+}
+
+static void lib_ring_buffer_pending_wakeup_chan(struct irq_work *entry)
+{
+       struct channel *chan = container_of(entry, struct channel, wakeup_pending);
+       wake_up_interruptible(&chan->read_wait);
+}
+
 /*
  * Must be called under cpu hotplug protection.
  */
@@ -268,6 +283,7 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf,
 
        init_waitqueue_head(&buf->read_wait);
        init_waitqueue_head(&buf->write_wait);
+       init_irq_work(&buf->wakeup_pending, lib_ring_buffer_pending_wakeup_buf);
        raw_spin_lock_init(&buf->raw_tick_nohz_spinlock);
 
        /*
@@ -854,6 +870,7 @@ struct channel *channel_create(const struct lib_ring_buffer_config *config,
        kref_init(&chan->ref);
        init_waitqueue_head(&chan->read_wait);
        init_waitqueue_head(&chan->hp_wait);
+       init_irq_work(&chan->wakeup_pending, lib_ring_buffer_pending_wakeup_chan);
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
@@ -963,6 +980,8 @@ void *channel_destroy(struct channel *chan)
        const struct lib_ring_buffer_config *config = &chan->backend.config;
        void *priv;
 
+       irq_work_sync(&chan->wakeup_pending);
+
        channel_unregister_notifiers(chan);
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
@@ -2356,13 +2375,14 @@ void lib_ring_buffer_check_deliver_slow(const struct lib_ring_buffer_config *con
                                                 commit_count, idx);
 
                /*
-                * RING_BUFFER_WAKEUP_BY_WRITER wakeup is not lock-free.
+                * RING_BUFFER_WAKEUP_BY_WRITER uses an irq_work to issue
+                * the wakeups.
                 */
                if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER
                    && atomic_long_read(&buf->active_readers)
                    && lib_ring_buffer_poll_deliver(config, buf, chan)) {
-                       wake_up_interruptible(&buf->read_wait);
-                       wake_up_interruptible(&chan->read_wait);
+                       irq_work_queue(&buf->wakeup_pending);
+                       irq_work_queue(&chan->wakeup_pending);
                }
 
        }