linux-kernel - Re: [PATCH] staging: vt6655: replace spin_lock_irqsave with spin

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Message-ID: <CA+sZ8B__mUdYxCBqzD4TGAKKcaa1FtLsrJCQD=b9aYBKJhZUTA@mail.gmail.com>
Date:   Thu, 15 Sep 2022 19:10:08 +0200
From:   Nam Cao <namcaov@...il.com>
To:     Philipp Hortmann <philipp.g.hortmann@...il.com>
Cc:     forest@...ttletooquiet.net, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev
Subject: Re: [PATCH] staging: vt6655: replace spin_lock_irqsave with spin_lock

On Wed, Sep 14, 2022 at 8:55 PM Philipp Hortmann
<philipp.g.hortmann@...il.com> wrote:
>
> On 9/14/22 10:00, Nam Cao wrote:
> > In vt6655 driver, there is a single interrupt handler: vnt_interrupt(),
> > and it does not take the spinlock. The interrupt handler only schedules
> > a workqueue, and the spinlock is taken in this workqueue. Thus, there is
> > no need to use spin_lock_irqsave, as the spinlock is never taken by an
> > interrupt. Replace spin_lock_irqsave (and spin_unlock_irqsave) with
> > spin_lock (and spin_unlock).
> >
> > Signed-off-by: Nam Cao <namcaov@...il.com>
>
> Hi Nam,
>
> I am lol ... my computer freezed (you don mind if I do not try this
> patch again? Please send a v2) ;-)
> I was digging for the log see below. (kern.log)
> I hope you can do something with it.

Thank you so much for testing the patch and providing the log. I think my patch
introduces deadlock, which caused your computer to freeze. My bad, sorry about
that. I may send v2 in the future, when I fully understand what is going on.

Best regards,
Nam