From: Andrew Halaney <ahalaney@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: bigeasy@linutronix.de, linux-kernel@vger.kernel.org,
linux-rt-users@vger.kernel.org, Chunyu Hu <chuhu@redhat.com>
Subject: Re: [RT PATCH] locking/rwsem-rt: Remove might_sleep() in __up_read()
Date: Thu, 8 Jul 2021 14:51:25 -0500 [thread overview]
Message-ID: <20210708195125.zxqsxy5bpccgxb2n@halaneylaptop> (raw)
In-Reply-To: <877dkoud19.ffs@nanos.tec.linutronix.de>
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 <chuhu@redhat.com>
> >> Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
> >> ---
> >> 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
next prev parent reply other threads:[~2021-07-08 19:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 22:19 [RT PATCH] locking/rwsem-rt: Remove might_sleep() in __up_read() Andrew Halaney
2021-04-26 16:42 ` Andrew Halaney
2021-04-26 18:16 ` Thomas Gleixner
2021-07-08 19:51 ` Andrew Halaney [this message]
2021-07-09 13:48 ` Thomas Gleixner
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