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

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: e30f53aad2 ("tracing: Do not busy wait in buffer splice")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2022-09-27 19:15:27 -04:00
parent 7e9fbbb1b7
commit f3ddb74ad0
2 changed files with 16 additions and 0 deletions
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1
include/linux/trace_events.h
View File

@ -92,6 +92,7 @@ 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

@ -8160,6 +8160,12 @@ 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);
@ -8313,6 +8319,8 @@ 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;
@ -8320,10 +8328,17 @@ 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;
}