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authorDave Jones <davej@redhat.com>2006-07-07 12:31:27 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-07 09:46:45 -0700
commita496e25dfb25493a57bcee5d66875d6ff80a9093 (patch)
treee0dc7f0f8151f6cf0ddc9ef987a6750e4e4a9ea3
parent120bda20c6f64b32e8bfbdd7b34feafaa5f5332e (diff)
[PATCH] Fix cpufreq vs hotplug lockdep recursion.
[ There's some not quite baked bits in cpufreq-git right now so sending this on as a patch instead ] On Thu, 2006-07-06 at 07:58 -0700, Tom London wrote: > After installing .2356 I get this each time I boot: > ======================================================= > [ INFO: possible circular locking dependency detected ] > ------------------------------------------------------- > S06cpuspeed/1620 is trying to acquire lock: > (dbs_mutex){--..}, at: [<c060d6bb>] mutex_lock+0x21/0x24 > > but task is already holding lock: > (cpucontrol){--..}, at: [<c060d6bb>] mutex_lock+0x21/0x24 > > which lock already depends on the new lock. > make sure the cpu hotplug recursive mutex (yuck) is taken early in the cpufreq codepaths to avoid a AB-BA deadlock. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/cpufreq/cpufreq.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1ba4039777e..8d328186f77 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -423,6 +423,8 @@ static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
if (cpufreq_parse_governor(str_governor, &new_policy.policy, &new_policy.governor))
return -EINVAL;
+ lock_cpu_hotplug();
+
/* Do not use cpufreq_set_policy here or the user_policy.max
will be wrongly overridden */
mutex_lock(&policy->lock);
@@ -432,6 +434,8 @@ static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
policy->user_policy.governor = policy->governor;
mutex_unlock(&policy->lock);
+ unlock_cpu_hotplug();
+
return ret ? ret : count;
}