From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Miao Xie , Steven Rostedt , Kamal Mostafa Subject: [PATCH 3.8 072/166] ftrace: Initialize the ftrace profiler for each possible cpu Date: Wed, 15 Jan 2014 13:51:26 -0800 Message-Id: <1389822780-4729-73-git-send-email-kamal@canonical.com> In-Reply-To: <1389822780-4729-1-git-send-email-kamal@canonical.com> References: <1389822780-4729-1-git-send-email-kamal@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.8.13.16 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Miao Xie commit c4602c1c818bd6626178d6d3fcc152d9f2f48ac0 upstream. Ftrace currently initializes only the online CPUs. This implementation has two problems: - If we online a CPU after we enable the function profile, and then run the test, we will lose the trace information on that CPU. Steps to reproduce: # echo 0 > /sys/devices/system/cpu/cpu1/online # cd /tracing/ # echo >> set_ftrace_filter # echo 1 > function_profile_enabled # echo 1 > /sys/devices/system/cpu/cpu1/online # run test - If we offline a CPU before we enable the function profile, we will not clear the trace information when we enable the function profile. It will trouble the users. Steps to reproduce: # cd /tracing/ # echo >> set_ftrace_filter # echo 1 > function_profile_enabled # run test # cat trace_stat/function* # echo 0 > /sys/devices/system/cpu/cpu1/online # echo 0 > function_profile_enabled # echo 1 > function_profile_enabled # cat trace_stat/function* # run test # cat trace_stat/function* So it is better that we initialize the ftrace profiler for each possible cpu every time we enable the function profile instead of just the online ones. Link: http://lkml.kernel.org/r/1387178401-10619-1-git-send-email-miaox@cn.fujitsu.com Signed-off-by: Miao Xie Signed-off-by: Steven Rostedt Signed-off-by: Kamal Mostafa --- kernel/trace/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 03dbc77..35d7565 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -720,7 +720,7 @@ static int ftrace_profile_init(void) int cpu; int ret = 0; - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { ret = ftrace_profile_init_cpu(cpu); if (ret) break; -- 1.8.3.2