From: Andrea Righi <righi.andrea@gmail.com>
To: davej@codemonkey.org.uk, Andrew Morton <akpm@linux-foundation.org>
Cc: cpufreq@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH -mm] cpufreq: BUG: using smp_processor_id() in preemptible code
Date: Thu, 18 Sep 2008 22:43:40 +0200 [thread overview]
Message-ID: <48D2BD7C.4070300@gmail.com> (raw)
Use get_cpu()/put_cpu() in cpufreq_ondemand init routine, instead of
smp_processor_id() to avoid the following BUG:
[ 35.313118] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/4952
[ 35.313132] caller is cpufreq_gov_dbs_init+0xa/0x8f [cpufreq_ondemand]
[ 35.313140] Pid: 4952, comm: modprobe Not tainted 2.6.27-rc5-mm1 #23
[ 35.313145] Call Trace:
[ 35.313158] [<ffffffff80361ff7>] debug_smp_processor_id+0xd7/0xe0
[ 35.313167] [<ffffffffa010800a>] cpufreq_gov_dbs_init+0xa/0x8f [cpufreq_ondemand]
[ 35.313176] [<ffffffff8020903b>] _stext+0x3b/0x160
[ 35.313185] [<ffffffff804768c5>] __mutex_unlock_slowpath+0xe5/0x190
[ 35.313195] [<ffffffff8026236a>] trace_hardirqs_on_caller+0xca/0x140
[ 35.313205] [<ffffffff8026ef4c>] sys_init_module+0xdc/0x210
[ 35.313212] [<ffffffff8020b7cb>] system_call_fastpath+0x16/0x1b
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
---
drivers/cpufreq/cpufreq_ondemand.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index aaa9e19..3098a94 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -638,8 +638,11 @@ static int __init cpufreq_gov_dbs_init(void)
{
int err;
cputime64_t wall;
- u64 idle_time = get_cpu_idle_time_us(smp_processor_id(), &wall);
+ u64 idle_time;
+ int cpu = get_cpu();
+ idle_time = get_cpu_idle_time_us(cpu, &wall);
+ put_cpu();
if (idle_time != -1ULL) {
/* Idle micro accounting is supported. Use finer thresholds */
dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
--
1.5.4.3
reply other threads:[~2008-09-18 20:43 UTC|newest]
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