From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758861Ab3GZNGb (ORCPT ); Fri, 26 Jul 2013 09:06:31 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:30237 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757038Ab3GZNFR (ORCPT ); Fri, 26 Jul 2013 09:05:17 -0400 X-Authority-Analysis: v=2.0 cv=KJ7Y/S5o c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=Ciwy3NGCPMMA:10 a=AGr_jgBdTAoA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=LiBVAXjy5VsA:10 a=VwQbUJbxAAAA:8 a=Q-fNiiVtAAAA:8 a=1XWaLZrsAAAA:8 a=S4XTqWYCxZEdMK2QbjYA:9 a=jeBq3FmKZ4MA:10 a=lcTMV_K9oDIA:10 a=UTB_XpHje0EA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Message-Id: <20130726130513.428993451@goodmis.org> User-Agent: quilt/0.60-1 Date: Fri, 26 Jul 2013 09:03:36 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Ingo Molnar , Andrew Morton , Arend van Spril , Alexander Z Lam , Vaibhav Nagarnaik , David Sharp , Subject: [PATCH 9/9] tracing: Remove locking trace_types_lock from tracing_reset_all_online_cpus() References: <20130726130327.911599518@goodmis.org> Content-Disposition: inline; filename=0009-tracing-Remove-locking-trace_types_lock-from-tracing.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (Red Hat)" Commit a82274151af "tracing: Protect ftrace_trace_arrays list in trace_events.c" added taking the trace_types_lock mutex in trace_events.c as there were several locations that needed it for protection. Unfortunately, it also encapsulated a call to tracing_reset_all_online_cpus() which also takes the trace_types_lock, causing a deadlock. This happens when a module has tracepoints and has been traced. When the module is removed, the trace events module notifier will grab the trace_types_lock, do a bunch of clean ups, and also clears the buffer by calling tracing_reset_all_online_cpus. This doesn't happen often which explains why it wasn't caught right away. Commit a82274151af was marked for stable, which means this must be sent to stable too. Link: http://lkml.kernel.org/r/51EEC646.7070306@broadcom.com Reported-by: Arend van Spril Tested-by: Arend van Spriel Cc: Alexander Z Lam Cc: Vaibhav Nagarnaik Cc: David Sharp Cc: stable@vger.kernel.org # 3.10 Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 69cba47..882ec1d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1224,18 +1224,17 @@ void tracing_reset_current(int cpu) tracing_reset(&global_trace.trace_buffer, cpu); } +/* Must have trace_types_lock held */ void tracing_reset_all_online_cpus(void) { struct trace_array *tr; - mutex_lock(&trace_types_lock); list_for_each_entry(tr, &ftrace_trace_arrays, list) { tracing_reset_online_cpus(&tr->trace_buffer); #ifdef CONFIG_TRACER_MAX_TRACE tracing_reset_online_cpus(&tr->max_buffer); #endif } - mutex_unlock(&trace_types_lock); } #define SAVED_CMDLINES 128 -- 1.7.10.4