From 7ee1768ddb3075ae3a0801cc2d0ea4195530a7db Mon Sep 17 00:00:00 2001 From: Pekka Paalanen Date: Sun, 23 Nov 2008 21:24:30 +0200 Subject: [PATCH] x86, mmiotrace: fix buffer overrun detection Impact: fix mmiotrace overrun tracing When ftrace framework moved to use the ring buffer facility, the buffer overrun detection was broken after 2.6.27 by commit | commit 3928a8a2d98081d1bc3c0a84a2d70e29b90ecf1c | Author: Steven Rostedt | Date: Mon Sep 29 23:02:41 2008 -0400 | | ftrace: make work with new ring buffer | | This patch ports ftrace over to the new ring buffer. The detection is now fixed by using the ring buffer API. When mmiotrace detects a buffer overrun, it will report the number of lost events. People reading an mmiotrace log must know if something was missed, otherwise the data may not make sense. Signed-off-by: Pekka Paalanen Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/trace_mmiotrace.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c index f28484618ff..e62cbf78eab 100644 --- a/kernel/trace/trace_mmiotrace.c +++ b/kernel/trace/trace_mmiotrace.c @@ -18,12 +18,14 @@ struct header_iter { static struct trace_array *mmio_trace_array; static bool overrun_detected; +static unsigned long prev_overruns; static void mmio_reset_data(struct trace_array *tr) { int cpu; overrun_detected = false; + prev_overruns = 0; tr->time_start = ftrace_now(tr->cpu); for_each_online_cpu(cpu) @@ -128,16 +130,12 @@ static void mmio_close(struct trace_iterator *iter) static unsigned long count_overruns(struct trace_iterator *iter) { - int cpu; unsigned long cnt = 0; -/* FIXME: */ -#if 0 - for_each_online_cpu(cpu) { - cnt += iter->overrun[cpu]; - iter->overrun[cpu] = 0; - } -#endif - (void)cpu; + unsigned long over = ring_buffer_overruns(iter->tr->buffer); + + if (over > prev_overruns) + cnt = over - prev_overruns; + prev_overruns = over; return cnt; } -- 2.20.1