From: Andreas Herrmann <andreas.herrmann3@amd.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: <linux-kernel@vger.kernel.org>, <cpufreq@vger.kernel.org>,
Tejun Heo <tj@kernel.org>, <stable@vger.kernel.org>
Subject: [PATCH] cpufreq, powernow-k8: Fix usage of smp_processor_id() in preemptible code
Date: Tue, 9 Oct 2012 21:38:44 +0200 [thread overview]
Message-ID: <20121009193844.GC7724@alberich> (raw)
Commit 6889125b8b4e09c5e53e6ecab3433bed1ce198c9
(cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU)
causes powernow-k8 to trigger a preempt warning, e.g.:
BUG: using smp_processor_id() in preemptible [00000000] code: cpufreq/3776
caller is powernowk8_target+0x20/0x49
Pid: 3776, comm: cpufreq Not tainted 3.6.0 #9
Call Trace:
[<ffffffff8125b447>] debug_smp_processor_id+0xc7/0xe0
[<ffffffff814877e7>] powernowk8_target+0x20/0x49
[<ffffffff81482b02>] __cpufreq_driver_target+0x82/0x8a
[<ffffffff81484fc6>] cpufreq_governor_performance+0x4e/0x54
[<ffffffff81482c50>] __cpufreq_governor+0x8c/0xc9
[<ffffffff81482e6f>] __cpufreq_set_policy+0x1a9/0x21e
[<ffffffff814839af>] store_scaling_governor+0x16f/0x19b
[<ffffffff81484f16>] ? cpufreq_update_policy+0x124/0x124
[<ffffffff8162b4a5>] ? _raw_spin_unlock_irqrestore+0x2c/0x49
[<ffffffff81483640>] store+0x60/0x88
[<ffffffff811708c0>] sysfs_write_file+0xf4/0x130
[<ffffffff8111243b>] vfs_write+0xb5/0x151
[<ffffffff811126e0>] sys_write+0x4a/0x71
[<ffffffff816319a9>] system_call_fastpath+0x16/0x1b
Fix this by using get_cpu/put_cpu in powernowk8_target().
Cc: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
---
drivers/cpufreq/powernow-k8.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 1a40935..3d1df2a 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1220,17 +1220,20 @@ static long powernowk8_target_fn(void *arg)
static int powernowk8_target(struct cpufreq_policy *pol,
unsigned targfreq, unsigned relation)
{
+ int this_cpu, ret;
struct powernowk8_target_arg pta = { .pol = pol, .targfreq = targfreq,
.relation = relation };
- /*
- * Must run on @pol->cpu. cpufreq core is responsible for ensuring
- * that we're bound to the current CPU and pol->cpu stays online.
- */
- if (smp_processor_id() == pol->cpu)
- return powernowk8_target_fn(&pta);
- else
- return work_on_cpu(pol->cpu, powernowk8_target_fn, &pta);
+ this_cpu = get_cpu();
+ if (this_cpu == pol->cpu) {
+ ret = powernowk8_target_fn(&pta);
+ put_cpu();
+ } else {
+ put_cpu();
+ ret = work_on_cpu(pol->cpu, powernowk8_target_fn, &pta);
+ }
+
+ return ret;
}
/* Driver entry point to verify the policy and range of frequencies */
--
1.7.12
next reply other threads:[~2012-10-09 19:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-09 19:38 Andreas Herrmann [this message]
2012-10-10 0:18 ` [PATCH] cpufreq, powernow-k8: Fix usage of smp_processor_id() in preemptible code Tejun Heo
2012-10-10 12:48 ` Andreas Herrmann
2012-10-10 12:51 ` Tejun Heo
2012-10-12 15:18 ` [PATCH] cpufreq, powernow-k8: Remove " Andreas Herrmann
2012-10-14 8:27 ` Rafael J. Wysocki
2012-10-14 15:40 ` Borislav Petkov
2012-10-15 5:50 ` Rafael J. Wysocki
2012-10-15 8:40 ` Borislav Petkov
2012-10-15 17:56 ` Rafael J. Wysocki
2012-10-24 21:57 ` Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121009193844.GC7724@alberich \
--to=andreas.herrmann3@amd.com \
--cc=cpufreq@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rjw@sisk.pl \
--cc=stable@vger.kernel.org \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).