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Date:   Fri, 11 Oct 2019 11:36:33 +0200
From:   Johan Hovold <johan@kernel.org>
To:     Daniel Vetter <daniel@ffwll.ch>
Cc:     Johan Hovold <johan@kernel.org>, Rob Clark <robdclark@gmail.com>,
        Sean Paul <sean@poorly.run>,
        Fabien Dessenne <fabien.dessenne@st.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Harald Freudenberger <freude@linux.ibm.com>,
        David Airlie <airlied@linux.ie>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, linux-s390@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH 0/4] treewide: fix interrupted release
Message-ID: <20191011093633.GD27819@localhost>
References: <20191010131333.23635-1-johan@kernel.org>
 <20191010135043.GA16989@phenom.ffwll.local>
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On Thu, Oct 10, 2019 at 03:50:43PM +0200, Daniel Vetter wrote:
> On Thu, Oct 10, 2019 at 03:13:29PM +0200, Johan Hovold wrote:
> > Two old USB drivers had a bug in them which could lead to memory leaks
> > if an interrupted process raced with a disconnect event.
> > 
> > Turns out we had a few more driver in other subsystems with the same
> > kind of bug in them.

> Random funny idea: Could we do some debug annotations (akin to
> might_sleep) that splats when you might_sleep_interruptible somewhere
> where interruptible sleeps are generally a bad idea? Like in
> fops->release?

There's nothing wrong with interruptible sleep in fops->release per se,
it's just that drivers cannot return -ERESTARTSYS and friends and expect
to be called again later.

The return value from release() is ignored by vfs, and adding a splat in
__fput() to catch these buggy drivers might be overkill.

Johan