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Date:   Wed, 11 May 2022 16:01:47 +0200
From:   Halil Pasic <pasic@linux.ibm.com>
To:     Jason Wang <jasowang@redhat.com>
Cc:     Cornelia Huck <cohuck@redhat.com>, mst <mst@redhat.com>,
        virtualization <virtualization@lists.linux-foundation.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Marc Zyngier <maz@kernel.org>, eperezma <eperezma@redhat.com>,
        Cindy Lu <lulu@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
        Halil Pasic <pasic@linux.ibm.com>
Subject: Re: [PATCH V4 0/9] rework on the IRQ hardening of virtio
Message-ID: <20220511160147.46cbf2fb.pasic@linux.ibm.com>
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        <CACGkMEvfkUpsY4LRTuH7w18DZdq+w3=Ef6b-0sG0XvzVUVKdzg@mail.gmail.com>
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On Wed, 11 May 2022 10:22:59 +0800
Jason Wang <jasowang@redhat.com> wrote:

> >        CPU0
> >        ----
> >   lock(&vcdev->irq_lock);
> >   <Interrupt>
> >     lock(&vcdev->irq_lock);
> >
> >  *** DEADLOCK ***  
> 
> It looks to me we need to use write_lock_irq()/write_unlock_irq() to
> do the synchronization.
> 
> And we probably need to keep the
> read_lock_irqsave()/read_lock_irqrestore() logic since I can see the
> virtio_ccw_int_handler() to be called from process context (e.g from
> the io_subchannel_quiesce()).
> 

Sounds correct.

Regards,
Halil