1 files changed, 35 insertions, 5 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 96079180de3d..5040d44fe5a3 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -445,7 +445,10 @@ int ring_buffer_print_page_header(struct trace_seq *s)
 struct rb_irq_work {
         struct irq_work                 work;
         wait_queue_head_t               waiters;
+        wait_queue_head_t               full_waiters;
         bool                            waiters_pending;
+        bool                            full_waiters_pending;
+        bool                            wakeup_full;
 };
 
 /*
@@ -527,6 +530,10 @@ static void rb_wake_up_waiters(struct irq_work *work)
         struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work);
 
         wake_up_all(&rbwork->waiters);
+        if (rbwork->wakeup_full) {
+                rbwork->wakeup_full = false;
+                wake_up_all(&rbwork->full_waiters);
+        }
 }
 
 /**
@@ -551,9 +558,11 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full)
          * data in any cpu buffer, or a specific buffer, put the
          * caller on the appropriate wait queue.
          */
-        if (cpu == RING_BUFFER_ALL_CPUS)
+        if (cpu == RING_BUFFER_ALL_CPUS) {
                 work = &buffer->irq_work;
-        else {
+                /* Full only makes sense on per cpu reads */
+                full = false;
+        } else {
                 if (!cpumask_test_cpu(cpu, buffer->cpumask))
                         return -ENODEV;
                 cpu_buffer = buffer->buffers[cpu];
@@ -562,7 +571,10 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full)
 
 
         while (true) {
-                prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE);
+                if (full)
+                        prepare_to_wait(&work->full_waiters, &wait, TASK_INTERRUPTIBLE);
+                else
+                        prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE);
 
                 /*
                  * The events can happen in critical sections where
@@ -584,7 +596,10 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full)
                  * that is necessary is that the wake up happens after
                  * a task has been queued. It's OK for spurious wake ups.
                  */
-                work->waiters_pending = true;
+                if (full)
+                        work->full_waiters_pending = true;
+                else
+                        work->waiters_pending = true;
 
                 if (signal_pending(current)) {
                         ret = -EINTR;
@@ -613,7 +628,10 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full)
                 schedule();
         }
 
-        finish_wait(&work->waiters, &wait);
+        if (full)
+                finish_wait(&work->full_waiters, &wait);
+        else
+                finish_wait(&work->waiters, &wait);
 
         return ret;
 }
@@ -1228,6 +1246,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int nr_pages, int cpu)
         init_completion(&cpu_buffer->update_done);
         init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters);
         init_waitqueue_head(&cpu_buffer->irq_work.waiters);
+        init_waitqueue_head(&cpu_buffer->irq_work.full_waiters);
 
         bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
                             GFP_KERNEL, cpu_to_node(cpu));
@@ -2799,6 +2818,8 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer,
 static __always_inline void
 rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
 {
+        bool pagebusy;
+
         if (buffer->irq_work.waiters_pending) {
                 buffer->irq_work.waiters_pending = false;
                 /* irq_work_queue() supplies it's own memory barriers */
@@ -2810,6 +2831,15 @@ rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
                 /* irq_work_queue() supplies it's own memory barriers */
                 irq_work_queue(&cpu_buffer->irq_work.work);
         }
+
+        pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;
+
+        if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) {
+                cpu_buffer->irq_work.wakeup_full = true;
+                cpu_buffer->irq_work.full_waiters_pending = false;
+                /* irq_work_queue() supplies it's own memory barriers */
+                irq_work_queue(&cpu_buffer->irq_work.work);
+        }
 }
 
 /**