From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758190Ab0CMC7w (ORCPT ); Fri, 12 Mar 2010 21:59:52 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:42385 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757806Ab0CMC65 (ORCPT ); Fri, 12 Mar 2010 21:58:57 -0500 X-Authority-Analysis: v=1.0 c=1 a=X2CRS_YvNPgA:10 a=GzHTLUccyWwA:10 a=20KFwNOVAAAA:8 a=VwQbUJbxAAAA:8 a=omOdbC7AAAAA:8 a=meVymXHHAAAA:8 a=MeR8Nho3YvcMjC9bkv8A:9 a=qbGv0Q4E2z_XmG4gKR8A:7 a=cWzmtdUlVHdwmH1-eDxTVx4g4dUA:4 a=jEp0ucaQiEUA:10 a=LI9Vle30uBYA:10 a=jeBq3FmKZ4MA:10 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.89.75 Message-Id: <20100313025854.864204406@goodmis.org> User-Agent: quilt/0.48-1 Date: Fri, 12 Mar 2010 21:56:58 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , Li Zefan , Lai Jiangshan , stable@kernel.org Subject: [PATCH 3/5] tracing: Use same local variable when resetting the ring buffer References: <20100313025655.104950166@goodmis.org> Content-Disposition: inline; filename=0003-tracing-Use-same-local-variable-when-resetting-the-r.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt In the ftrace code that resets the ring buffer it references the buffer with a local variable, but then uses the tr->buffer as the parameter to reset. If the wakeup tracer is running, which can switch the tr->buffer with the max saved buffer, this can break the requirement of disabling the buffer before the reset. buffer = tr->buffer; ring_buffer_record_disable(buffer); synchronize_sched(); __tracing_reset(tr->buffer, cpu); If the tr->buffer is swapped, then the reset is not happening to the buffer that was disabled. This will cause the ring buffer to fail. Found with Li Zefan's ftrace_stress_test. Cc: stable@kernel.org Reported-by: Lai Jiangshan Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6af8d7b..60de37b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -840,10 +840,10 @@ out: mutex_unlock(&trace_types_lock); } -static void __tracing_reset(struct trace_array *tr, int cpu) +static void __tracing_reset(struct ring_buffer *buffer, int cpu) { ftrace_disable_cpu(); - ring_buffer_reset_cpu(tr->buffer, cpu); + ring_buffer_reset_cpu(buffer, cpu); ftrace_enable_cpu(); } @@ -855,7 +855,7 @@ void tracing_reset(struct trace_array *tr, int cpu) /* Make sure all commits have finished */ synchronize_sched(); - __tracing_reset(tr, cpu); + __tracing_reset(buffer, cpu); ring_buffer_record_enable(buffer); } @@ -873,7 +873,7 @@ void tracing_reset_online_cpus(struct trace_array *tr) tr->time_start = ftrace_now(tr->cpu); for_each_online_cpu(cpu) - __tracing_reset(tr, cpu); + __tracing_reset(buffer, cpu); ring_buffer_record_enable(buffer); } -- 1.7.0