From: Steven Rostedt (VMware) Date: Fri, 27 Nov 2020 16:20:58 +0000 (-0500) Subject: ring-buffer: Update write stamp with the correct ts X-Git-Tag: v5.9.14~61 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fd3a46f25bb4ffc1f80fe1925a031a82982aeb14;p=thirdparty%2Fkernel%2Fstable.git ring-buffer: Update write stamp with the correct ts commit 55ea4cf403800af2ce6b125bc3d853117e0c0456 upstream. The write stamp, used to calculate deltas between events, was updated with the stale "ts" value in the "info" structure, and not with the updated "ts" variable. This caused the deltas between events to be inaccurate, and when crossing into a new sub buffer, had time go backwards. Link: https://lkml.kernel.org/r/20201124223917.795844-1-elavila@google.com Cc: stable@vger.kernel.org Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp") Reported-by: "J. Avila" Tested-by: Daniel Mentz Tested-by: Will McVicker Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 9d69fdf0c5205..1bcccff95bd2a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3291,7 +3291,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, /* Nothing came after this event between C and E */ info->delta = ts - info->after; (void)rb_time_cmpxchg(&cpu_buffer->write_stamp, - info->after, info->ts); + info->after, ts); info->ts = ts; } else { /*