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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2015-12-22 17:25:18 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-07 22:43:17 -0800
commit4c127fd16e6b33ecb7badc091480c84ea9aebeb6 (patch)
tree6f1d3882b0b6803660b9f89e610e56a04d6c983a /drivers/hwtracing
parent042d4460b5b4379a12f375045ff9065cf6758735 (diff)
stm class: Fix locking in unbinding policy path
Right now, if stm device removal has to unbind from a policy (that is, an stm device that has STP policy, gets removed), it will trigger a nested lock on the stm device's policy mutex. This patch fixes the problem by moving the locking from the policy unbinding to policy removal (configfs path), where it's actually needed; the other caller of the policy unbinding function already takes the mutex around the call. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r--drivers/hwtracing/stm/policy.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
index 11ab6d01adf6..94d3abfb737a 100644
--- a/drivers/hwtracing/stm/policy.c
+++ b/drivers/hwtracing/stm/policy.c
@@ -272,13 +272,17 @@ void stp_policy_unbind(struct stp_policy *policy)
{
struct stm_device *stm = policy->stm;
+ /*
+ * stp_policy_release() will not call here if the policy is already
+ * unbound; other users should not either, as no link exists between
+ * this policy and anything else in that case
+ */
if (WARN_ON_ONCE(!policy->stm))
return;
- mutex_lock(&stm->policy_mutex);
- stm->policy = NULL;
- mutex_unlock(&stm->policy_mutex);
+ lockdep_assert_held(&stm->policy_mutex);
+ stm->policy = NULL;
policy->stm = NULL;
stm_put_device(stm);
@@ -287,8 +291,16 @@ void stp_policy_unbind(struct stp_policy *policy)
static void stp_policy_release(struct config_item *item)
{
struct stp_policy *policy = to_stp_policy(item);
+ struct stm_device *stm = policy->stm;
+ /* a policy *can* be unbound and still exist in configfs tree */
+ if (!stm)
+ return;
+
+ mutex_lock(&stm->policy_mutex);
stp_policy_unbind(policy);
+ mutex_unlock(&stm->policy_mutex);
+
kfree(policy);
}