There's no chance of sleeping here, the reader is giving up the
lock and possibly waking up the writer who is waiting on it.
Reported-by: Chunyu Hu <[email protected]>
Signed-off-by: Andrew Halaney <[email protected]>
---
Hello,
I ran into a warning caused by this, and I think the warning is
incorrect. Please let me know if I'm wrong!
I'm working off of linux-5.12.y-rt, but this applies cleanly to older
stable branches as well.
Thanks,
Andrew
kernel/locking/rwsem-rt.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
index 274172d5bb3a..b61edc4dcb73 100644
--- a/kernel/locking/rwsem-rt.c
+++ b/kernel/locking/rwsem-rt.c
@@ -198,7 +198,6 @@ void __up_read(struct rw_semaphore *sem)
if (!atomic_dec_and_test(&sem->readers))
return;
- might_sleep();
raw_spin_lock_irq(&m->wait_lock);
/*
* Wake the writer, i.e. the rtmutex owner. It might release the
--
2.30.2
On Tue, Apr 06, 2021 at 05:19:52PM -0500, Andrew Halaney wrote:
> There's no chance of sleeping here, the reader is giving up the
> lock and possibly waking up the writer who is waiting on it.
>
> Reported-by: Chunyu Hu <[email protected]>
> Signed-off-by: Andrew Halaney <[email protected]>
> ---
> Hello,
>
> I ran into a warning caused by this, and I think the warning is
> incorrect. Please let me know if I'm wrong!
> I'm working off of linux-5.12.y-rt, but this applies cleanly to older
> stable branches as well.
>
> Thanks,
> Andrew
>
> kernel/locking/rwsem-rt.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
> index 274172d5bb3a..b61edc4dcb73 100644
> --- a/kernel/locking/rwsem-rt.c
> +++ b/kernel/locking/rwsem-rt.c
> @@ -198,7 +198,6 @@ void __up_read(struct rw_semaphore *sem)
> if (!atomic_dec_and_test(&sem->readers))
> return;
>
> - might_sleep();
> raw_spin_lock_irq(&m->wait_lock);
> /*
> * Wake the writer, i.e. the rtmutex owner. It might release the
> --
> 2.30.2
>
Just a gentle follow up, any feedback?
Thanks,
Andrew
On Mon, Apr 26 2021 at 11:42, Andrew Halaney wrote:
> On Tue, Apr 06, 2021 at 05:19:52PM -0500, Andrew Halaney wrote:
>> There's no chance of sleeping here, the reader is giving up the
>> lock and possibly waking up the writer who is waiting on it.
>>
>> Reported-by: Chunyu Hu <[email protected]>
>> Signed-off-by: Andrew Halaney <[email protected]>
>> ---
>> Hello,
>>
>> I ran into a warning caused by this, and I think the warning is
>> incorrect. Please let me know if I'm wrong!
>> I'm working off of linux-5.12.y-rt, but this applies cleanly to older
>> stable branches as well.
>>
>> Thanks,
>> Andrew
>>
>> kernel/locking/rwsem-rt.c | 1 -
>> 1 file changed, 1 deletion(-)
>>
>> diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
>> index 274172d5bb3a..b61edc4dcb73 100644
>> --- a/kernel/locking/rwsem-rt.c
>> +++ b/kernel/locking/rwsem-rt.c
>> @@ -198,7 +198,6 @@ void __up_read(struct rw_semaphore *sem)
>> if (!atomic_dec_and_test(&sem->readers))
>> return;
>>
>> - might_sleep();
>> raw_spin_lock_irq(&m->wait_lock);
>> /*
>> * Wake the writer, i.e. the rtmutex owner. It might release the
>> --
>> 2.30.2
>
> Just a gentle follow up, any feedback?
Looks correct. Will go into the next rt-release.
Thanks,
tglx
On Mon, Apr 26, 2021 at 08:16:34PM +0200, Thomas Gleixner wrote:
> On Mon, Apr 26 2021 at 11:42, Andrew Halaney wrote:
> > On Tue, Apr 06, 2021 at 05:19:52PM -0500, Andrew Halaney wrote:
> >> There's no chance of sleeping here, the reader is giving up the
> >> lock and possibly waking up the writer who is waiting on it.
> >>
> >> Reported-by: Chunyu Hu <[email protected]>
> >> Signed-off-by: Andrew Halaney <[email protected]>
> >> ---
> >> Hello,
> >>
> >> I ran into a warning caused by this, and I think the warning is
> >> incorrect. Please let me know if I'm wrong!
> >> I'm working off of linux-5.12.y-rt, but this applies cleanly to older
> >> stable branches as well.
> >>
> >> Thanks,
> >> Andrew
> >>
> >> kernel/locking/rwsem-rt.c | 1 -
> >> 1 file changed, 1 deletion(-)
> >>
> >> diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
> >> index 274172d5bb3a..b61edc4dcb73 100644
> >> --- a/kernel/locking/rwsem-rt.c
> >> +++ b/kernel/locking/rwsem-rt.c
> >> @@ -198,7 +198,6 @@ void __up_read(struct rw_semaphore *sem)
> >> if (!atomic_dec_and_test(&sem->readers))
> >> return;
> >>
> >> - might_sleep();
> >> raw_spin_lock_irq(&m->wait_lock);
> >> /*
> >> * Wake the writer, i.e. the rtmutex owner. It might release the
> >> --
> >> 2.30.2
> >
> > Just a gentle follow up, any feedback?
>
> Looks correct. Will go into the next rt-release.
>
> Thanks,
>
> tglx
>
Hi Thomas,
I see a new release (v5.13-rt1) was created, and with it rwsem
was overhauled entirely making this patch pointless for linux-rt-devel.
That being said, it's a little unclear to me how RT only patches
make their way to the maintained branches over in linux-stable-rt.
I think it should be applied to:
v4.9-rt
v4.14-rt
v4.19-rt
v5.4-rt
v5.10-rt
to remove the incorrect warning, unless those branches plan to backport
the latest RT patchset with the new rwsem implementation. Is there a
proper way for me signal that?
Thanks,
Andrew
Andrew,
On Thu, Jul 08 2021 at 14:51, Andrew Halaney wrote:
Cc+ stable-rt folks and leave context untrimmed.
> On Mon, Apr 26, 2021 at 08:16:34PM +0200, Thomas Gleixner wrote:
>> On Mon, Apr 26 2021 at 11:42, Andrew Halaney wrote:
>> > On Tue, Apr 06, 2021 at 05:19:52PM -0500, Andrew Halaney wrote:
>> >> There's no chance of sleeping here, the reader is giving up the
>> >> lock and possibly waking up the writer who is waiting on it.
>> >>
>> >> Reported-by: Chunyu Hu <[email protected]>
>> >> Signed-off-by: Andrew Halaney <[email protected]>
>> >> ---
>> >> Hello,
>> >>
>> >> I ran into a warning caused by this, and I think the warning is
>> >> incorrect. Please let me know if I'm wrong!
>> >> I'm working off of linux-5.12.y-rt, but this applies cleanly to older
>> >> stable branches as well.
>> >>
>> >> Thanks,
>> >> Andrew
>> >>
>> >> kernel/locking/rwsem-rt.c | 1 -
>> >> 1 file changed, 1 deletion(-)
>> >>
>> >> diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
>> >> index 274172d5bb3a..b61edc4dcb73 100644
>> >> --- a/kernel/locking/rwsem-rt.c
>> >> +++ b/kernel/locking/rwsem-rt.c
>> >> @@ -198,7 +198,6 @@ void __up_read(struct rw_semaphore *sem)
>> >> if (!atomic_dec_and_test(&sem->readers))
>> >> return;
>> >>
>> >> - might_sleep();
>> >> raw_spin_lock_irq(&m->wait_lock);
>> >> /*
>> >> * Wake the writer, i.e. the rtmutex owner. It might release the
>> >> --
>> >> 2.30.2
>> >
>> > Just a gentle follow up, any feedback?
>>
>> Looks correct. Will go into the next rt-release.
>>
>> Thanks,
>>
>> tglx
>>
>
> Hi Thomas,
>
> I see a new release (v5.13-rt1) was created, and with it rwsem
> was overhauled entirely making this patch pointless for linux-rt-devel.
>
> That being said, it's a little unclear to me how RT only patches
> make their way to the maintained branches over in linux-stable-rt.
> I think it should be applied to:
> v4.9-rt
> v4.14-rt
> v4.19-rt
> v5.4-rt
> v5.10-rt
> to remove the incorrect warning, unless those branches plan to backport
> the latest RT patchset with the new rwsem implementation. Is there a
> proper way for me signal that?
See Cc.
Thanks,
tglx