From: Steven Rostedt (Red Hat) Date: Mon, 23 Nov 2015 22:35:24 +0000 (-0500) Subject: ring-buffer: Put back the length if crossed page with add_timestamp X-Git-Tag: v4.4-rc4~15^2~1 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=bd1b7cd360f529394936f28746eb4aaa12d6770a;p=linux-2.6-block.git ring-buffer: Put back the length if crossed page with add_timestamp Commit fcc742eaad7c "ring-buffer: Add event descriptor to simplify passing data" added a descriptor that holds various data instead of passing around several variables through parameters. The problem was that one of the parameters was modified in a function and the code was designed not to have an effect on that modified parameter. Now that the parameter is a descriptor and any modifications to it are non-volatile, the size of the data could be unnecessarily expanded. Remove the extra space added if a timestamp was added and the event went across the page. Cc: stable@vger.kernel.org # 4.3+ Fixes: fcc742eaad7c "ring-buffer: Add event descriptor to simplify passing data" Signed-off-by: Steven Rostedt --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 4dd6d5bc4e11..9c6045a27ba3 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2797,8 +2797,11 @@ rb_reserve_next_event(struct ring_buffer *buffer, event = __rb_reserve_next(cpu_buffer, &info); - if (unlikely(PTR_ERR(event) == -EAGAIN)) + if (unlikely(PTR_ERR(event) == -EAGAIN)) { + if (info.add_timestamp) + info.length -= RB_LEN_TIME_EXTEND; goto again; + } if (!event) goto out_fail;