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tracing: Wake up ring buffer waiters on closing of the file

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commit f3ddb74ad0790030c9592229fb14d8c451f4e9a8 upstream.

When the file that represents the ring buffer is closed, there may be
waiters waiting on more input from the ring buffer. Call
ring_buffer_wake_waiters() to wake up any waiters when the file is
closed.

Link: https://lkml.kernel.org/r/20220927231825.182416969@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: e30f53aad2202 ("tracing: Do not busy wait in buffer splice")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steven Rostedt (Google) 2022-09-27 19:15:27 -04:00 committed by Greg Kroah-Hartman
parent 48272aa48d
commit 2475de2bc0
2 changed files with 16 additions and 0 deletions
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1
include/linux/trace_events.h
View File

@ -91,6 +91,7 @@ struct trace_iterator {
unsigned int temp_size;
char *fmt; /* modified format holder */
unsigned int fmt_size;
long wait_index;
/* trace_seq for __print_flags() and __print_symbolic() etc. */
struct trace_seq tmp_seq;

15
kernel/trace/trace.c
View File

@ -8117,6 +8117,12 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
__trace_array_put(iter->tr);
iter->wait_index++;
/* Make sure the waiters see the new wait_index */
smp_wmb();
ring_buffer_wake_waiters(iter->array_buffer->buffer, iter->cpu_file);
if (info->spare)
ring_buffer_free_read_page(iter->array_buffer->buffer,
info->spare_cpu, info->spare);
@ -8270,6 +8276,8 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
/* did we read anything? */
if (!spd.nr_pages) {
long wait_index;
if (ret)
goto out;
@ -8277,10 +8285,17 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK))
goto out;
wait_index = READ_ONCE(iter->wait_index);
ret = wait_on_pipe(iter, iter->tr->buffer_percent);
if (ret)
goto out;
/* Make sure we see the new wait_index */
smp_rmb();
if (wait_index != iter->wait_index)
goto out;
goto again;
}