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Groups > linux.kernel > #1327938
| From | Alexander Shishkin <alexander.shishkin@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [QUEUED v0 04/19] stm class: Fix locking in unbinding policy path |
| Date | 2016-02-05 17:50 +0100 |
| Message-ID | <qYRK2-2JM-31@gated-at.bofh.it> (permalink) |
| References | <qYRAm-2Gm-19@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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>
---
drivers/hwtracing/stm/policy.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
index 11ab6d01ad..94d3abfb73 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);
}
--
2.7.0
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[QUEUED v0 00/19] stm class/intel_th: Patches in my queue Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 10/19] stm class: Use a signed return type for stm_find_master_chan Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 05/19] stm class: Fix link list locking Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 01/19] stm class: Hide STM-specific options if STM is disabled Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 06/19] stm class: Fix an off-by-one in master array allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 07/19] stm class: Prevent user-controllable allocations Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 02/19] intel_th: INTEL_TH should depend on HAS_DMA Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 09/19] intel_th: pci: Add Broxton SOC support Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 11/19] intel_th: Depend on HAS_IOMEM Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 12/19] intel_th: gth: Remove commented-out code Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 08/19] intel_th: pci: Add Apollo Lake SOC support Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:40 +0100 [QUEUED v0 03/19] stm class: Select CONFIG_SRCU Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 18/19] intel_th: Set root device's drvdata early Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 17/19] stm class: dummy_stm: Create multiple devices Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 16/19] stm class: Support devices with multiple instances Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 04/19] stm class: Fix locking in unbinding policy path Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 19/19] intel_th: Use real device index in the node names Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 13/19] intel_th: Update scratchpad bits according to enabled output activity Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 15/19] intel_th: sth: Sanitize packet callback's return values Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100 [QUEUED v0 14/19] stm class: Use driver's packet callback's return value Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-02-05 17:50 +0100
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