diff options
| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-09-28 13:39:38 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-10-26 12:34:31 +0200 |
| commit | be60f698c2769ce8cd9bc8df294e3a0df0924e51 (patch) | |
| tree | 744463501926eefbbe2969ffb41affa30d3423e3 /kernel | |
| parent | 5201dd81aef7f2b864f765cc4fa54e7c11f89c67 (diff) | |
ring-buffer: Add ring_buffer_wake_waiters()
commit 7e9fbbb1b776d8d7969551565bc246f74ec53b27 upstream.
On closing of a file that represents a ring buffer or flushing the file,
there may be waiters on the ring buffer that needs to be woken up and exit
the ring_buffer_wait() function.
Add ring_buffer_wake_waiters() to wake up the waiters on the ring buffer
and allow them to exit the wait loop.
Link: https://lkml.kernel.org/r/20220928133938.28dc2c27@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 15693458c4bc0 ("tracing/ring-buffer: Move poll wake ups into ring buffer code")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 5613b5ea766e..eda8f5a744a7 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -405,6 +405,7 @@ struct rb_irq_work { struct irq_work work; wait_queue_head_t waiters; wait_queue_head_t full_waiters; + long wait_index; bool waiters_pending; bool full_waiters_pending; bool wakeup_full; @@ -889,6 +890,37 @@ static void rb_wake_up_waiters(struct irq_work *work) } /** + * ring_buffer_wake_waiters - wake up any waiters on this ring buffer + * @buffer: The ring buffer to wake waiters on + * + * In the case of a file that represents a ring buffer is closing, + * it is prudent to wake up any waiters that are on this. + */ +void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + struct rb_irq_work *rbwork; + + if (cpu == RING_BUFFER_ALL_CPUS) { + + /* Wake up individual ones too. One level recursion */ + for_each_buffer_cpu(buffer, cpu) + ring_buffer_wake_waiters(buffer, cpu); + + rbwork = &buffer->irq_work; + } else { + cpu_buffer = buffer->buffers[cpu]; + rbwork = &cpu_buffer->irq_work; + } + + rbwork->wait_index++; + /* make sure the waiters see the new index */ + smp_wmb(); + + rb_wake_up_waiters(&rbwork->work); +} + +/** * ring_buffer_wait - wait for input to the ring buffer * @buffer: buffer to wait on * @cpu: the cpu buffer to wait on @@ -903,6 +935,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full) struct ring_buffer_per_cpu *cpu_buffer; DEFINE_WAIT(wait); struct rb_irq_work *work; + long wait_index; int ret = 0; /* @@ -921,6 +954,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full) work = &cpu_buffer->irq_work; } + wait_index = READ_ONCE(work->wait_index); while (true) { if (full) @@ -985,6 +1019,11 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full) } schedule(); + + /* Make sure to see the new wait index */ + smp_rmb(); + if (wait_index != work->wait_index) + break; } if (full) |