diff options
| author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2015-12-22 17:25:18 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-07 22:43:17 -0800 |
| commit | 4c127fd16e6b33ecb7badc091480c84ea9aebeb6 (patch) | |
| tree | 6f1d3882b0b6803660b9f89e610e56a04d6c983a /drivers/hwtracing | |
| parent | 042d4460b5b4379a12f375045ff9065cf6758735 (diff) | |
| download | lwn-4c127fd16e6b33ecb7badc091480c84ea9aebeb6.tar.gz lwn-4c127fd16e6b33ecb7badc091480c84ea9aebeb6.zip | |
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.c | 18 |
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); } |