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* [Linux-kernel-mentees] [PATCH v2] drivers: soc: ti: knav_qmss_queue: Pass lockdep expression to RCU lists
@ 2020-01-17 13:30 Amol Grover
  2020-01-17 18:24 ` santosh.shilimkar
  0 siblings, 1 reply; 6+ messages in thread
From: Amol Grover @ 2020-01-17 13:30 UTC (permalink / raw)
  To: Santosh Shilimkar
  Cc: Paul E . McKenney, linux-kernel, linux-arm-kernel,
	Joel Fernandes, linux-kernel-mentees

inst->handles is traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of knav_dev_lock.

Hence, add corresponding lockdep expression to silence false-positive
lockdep warnings, and harden RCU lists.

Add macro for the corresponding lockdep expression.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v2:
- Remove rcu_read_lock_held() from lockdep expression since it is
  implicitly checked for.

 drivers/soc/ti/knav_qmss_queue.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/ti/knav_qmss_queue.c b/drivers/soc/ti/knav_qmss_queue.c
index 1ccc9064e1eb..37f3db6c041c 100644
--- a/drivers/soc/ti/knav_qmss_queue.c
+++ b/drivers/soc/ti/knav_qmss_queue.c
@@ -25,6 +25,8 @@
 
 static struct knav_device *kdev;
 static DEFINE_MUTEX(knav_dev_lock);
+#define knav_dev_lock_held() \
+	lockdep_is_held(&knav_dev_lock)
 
 /* Queue manager register indices in DTS */
 #define KNAV_QUEUE_PEEK_REG_INDEX	0
@@ -52,8 +54,9 @@ static DEFINE_MUTEX(knav_dev_lock);
 #define knav_queue_idx_to_inst(kdev, idx)			\
 	(kdev->instances + (idx << kdev->inst_shift))
 
-#define for_each_handle_rcu(qh, inst)			\
-	list_for_each_entry_rcu(qh, &inst->handles, list)
+#define for_each_handle_rcu(qh, inst)				\
+	list_for_each_entry_rcu(qh, &inst->handles, list,	\
+				knav_dev_lock_held())
 
 #define for_each_instance(idx, inst, kdev)		\
 	for (idx = 0, inst = kdev->instances;		\
-- 
2.24.1

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^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [Linux-kernel-mentees] [PATCH v2] drivers: soc: ti: knav_qmss_queue: Pass lockdep expression to RCU lists
@ 2020-01-18  4:24 Amol Grover
  2020-01-18 18:06 ` santosh.shilimkar
  0 siblings, 1 reply; 6+ messages in thread
From: Amol Grover @ 2020-01-18  4:24 UTC (permalink / raw)
  To: Santosh Shilimkar, Olof Johansson
  Cc: Paul E . McKenney, santosh.shilimkar, linux-kernel, soc, arm,
	Joel Fernandes, linux-kernel-mentees, linux-arm-kernel

inst->handles is traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of knav_dev_lock.

Hence, add corresponding lockdep expression to silence false-positive
lockdep warnings, and harden RCU lists.

Add macro for the corresponding lockdep expression.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v2:
- Remove rcu_read_lock_held() from lockdep expression since it is
  implicitly checked for.

 drivers/soc/ti/knav_qmss_queue.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/ti/knav_qmss_queue.c b/drivers/soc/ti/knav_qmss_queue.c
index 1ccc9064e1eb..37f3db6c041c 100644
--- a/drivers/soc/ti/knav_qmss_queue.c
+++ b/drivers/soc/ti/knav_qmss_queue.c
@@ -25,6 +25,8 @@
 
 static struct knav_device *kdev;
 static DEFINE_MUTEX(knav_dev_lock);
+#define knav_dev_lock_held() \
+	lockdep_is_held(&knav_dev_lock)
 
 /* Queue manager register indices in DTS */
 #define KNAV_QUEUE_PEEK_REG_INDEX	0
@@ -52,8 +54,9 @@ static DEFINE_MUTEX(knav_dev_lock);
 #define knav_queue_idx_to_inst(kdev, idx)			\
 	(kdev->instances + (idx << kdev->inst_shift))
 
-#define for_each_handle_rcu(qh, inst)			\
-	list_for_each_entry_rcu(qh, &inst->handles, list)
+#define for_each_handle_rcu(qh, inst)				\
+	list_for_each_entry_rcu(qh, &inst->handles, list,	\
+				knav_dev_lock_held())
 
 #define for_each_instance(idx, inst, kdev)		\
 	for (idx = 0, inst = kdev->instances;		\
-- 
2.24.1

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Linux-kernel-mentees@lists.linuxfoundation.org
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^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2020-01-18 18:07 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-17 13:30 [Linux-kernel-mentees] [PATCH v2] drivers: soc: ti: knav_qmss_queue: Pass lockdep expression to RCU lists Amol Grover
2020-01-17 18:24 ` santosh.shilimkar
2020-01-17 19:25   ` Olof Johansson
2020-01-18  4:07     ` Amol Grover
2020-01-18  4:24 Amol Grover
2020-01-18 18:06 ` santosh.shilimkar

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