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tracing: Wake up waiters when tracing is disabled

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commit 2b0fd9a59b upstream.

When tracing is disabled, there's no reason that waiters should stay
waiting, wake them up, otherwise tasks get stuck when they should be
flushing the buffers.

Cc: stable@vger.kernel.org
Fixes: e30f53aad2 ("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) 2022-09-28 18:22:20 -04:00 committed by Greg Kroah-Hartman
parent 2475de2bc0
commit 32eb54a986
1 changed files with 6 additions and 0 deletions
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6
kernel/trace/trace.c
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@ -8291,6 +8291,10 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
if (ret)
goto out;
/* No need to wait after waking up when tracing is off */
if (!tracer_tracing_is_on(iter->tr))
goto out;
/* Make sure we see the new wait_index */
smp_rmb();
if (wait_index != iter->wait_index)
@ -9000,6 +9004,8 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
tracer_tracing_off(tr);
if (tr->current_trace->stop)
tr->current_trace->stop(tr);
/* Wake up any waiters */
ring_buffer_wake_waiters(buffer, RING_BUFFER_ALL_CPUS);
}
mutex_unlock(&trace_types_lock);
}