[v2] drivers: soc: ti: knav_qmss_queue: Pass lockdep expression to RCU lists
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Message ID 20200117133048.31708-1-frextrite@gmail.com
State Mainlined
Commit feec214afb53f17554c9c0c85f72de709b7ba3e4
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Series
  • [v2] drivers: soc: ti: knav_qmss_queue: Pass lockdep expression to RCU lists
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Commit Message

Amol Grover Jan. 17, 2020, 1:30 p.m. UTC
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(-)

Comments

Santosh Shilimkar Jan. 17, 2020, 6:24 p.m. UTC | #1
On 1/17/20 5:30 AM, Amol Grover wrote:
> 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.
> 
Looks fine to me.

Hi Olof, Arnd,
Can you please pick this one and apply to your driver-soc branch ?
I already sent out pull request and hence the request.

regards,
Santosh
Olof Johansson Jan. 17, 2020, 7:25 p.m. UTC | #2
On Fri, Jan 17, 2020 at 10:24:04AM -0800, santosh.shilimkar@oracle.com wrote:
> On 1/17/20 5:30 AM, Amol Grover wrote:
> > 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.
> > 
> Looks fine to me.
> 
> Hi Olof, Arnd,
> Can you please pick this one and apply to your driver-soc branch ?
> I already sent out pull request and hence the request.

Hi,

Can you please email the whole patch with sign-off to
soc@kernel.org? Otherwise it won't end up in patchwork, which is how we track
patches and pull requests these days.


Thanks,

-Olof
Amol Grover Jan. 18, 2020, 4:07 a.m. UTC | #3
On Fri, Jan 17, 2020 at 11:25:55AM -0800, Olof Johansson wrote:
> On Fri, Jan 17, 2020 at 10:24:04AM -0800, santosh.shilimkar@oracle.com wrote:
> > On 1/17/20 5:30 AM, Amol Grover wrote:
> > > 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.
> > > 
> > Looks fine to me.
> > 
> > Hi Olof, Arnd,
> > Can you please pick this one and apply to your driver-soc branch ?
> > I already sent out pull request and hence the request.
> 
> Hi,
> 
> Can you please email the whole patch with sign-off to
> soc@kernel.org? Otherwise it won't end up in patchwork, which is how we track
> patches and pull requests these days.
> 

Thank you Santosh and Olof. I'm resending the patch to soc@kernel.org
as well.

Thanks
Amol

> 
> Thanks,
> 
> -Olof

Patch
diff mbox series

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;		\