From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760651Ab3GSOO7 (ORCPT ); Fri, 19 Jul 2013 10:14:59 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:32652 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755765Ab3GSOOu (ORCPT ); Fri, 19 Jul 2013 10:14:50 -0400 X-Authority-Analysis: v=2.0 cv=e9yEuNV/ c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=Ciwy3NGCPMMA:10 a=xVgifgPhGo0A:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=CYTwX-1TC0UA:10 a=20KFwNOVAAAA:8 a=VwQbUJbxAAAA:8 a=JfrnYn6hAAAA:8 a=9eudB-iudPty_y5Cnl4A:9 a=jEp0ucaQiEUA:10 a=3Rfx1nUSh_UA:10 a=jeBq3FmKZ4MA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Message-Id: <20130719141448.888692179@goodmis.org> User-Agent: quilt/0.60-1 Date: Fri, 19 Jul 2013 10:12:28 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Frederic Weisbecker , Andrew Morton , Peter Zijlstra , Oleg Nesterov Subject: [for-next-3.11][PATCH 04/12] tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty References: <20130719141224.703522101@goodmis.org> Content-Disposition: inline; filename=0004-tracing-function-Avoid-perf_trace_buf_-if-event_func.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleg Nesterov perf_trace_buf_prepare() + perf_trace_buf_submit(head, task => NULL) make no sense if hlist_empty(head). Change perf_ftrace_function_call() to check event_function.perf_events beforehand. Link: http://lkml.kernel.org/r/20130617170204.GA19803@redhat.com Acked-by: Peter Zijlstra Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt --- kernel/trace/trace_event_perf.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 84b1e04..12df557 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -266,6 +266,10 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, struct pt_regs regs; int rctx; + head = this_cpu_ptr(event_function.perf_events); + if (hlist_empty(head)) + return; + #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ sizeof(u64)) - sizeof(u32)) @@ -279,8 +283,6 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, entry->ip = ip; entry->parent_ip = parent_ip; - - head = this_cpu_ptr(event_function.perf_events); perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0, 1, ®s, head, NULL); -- 1.7.10.4