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From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	linux-iio <linux-iio@vger.kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH v1 1/5] iio: pressure: bmp280: Tolerate IRQ before registering
Date: Sun, 22 Mar 2020 23:15:13 +0200	[thread overview]
Message-ID: <CAHp75VcUPSmCnKFSm8y6Nq_qCcMHHihACC+49FyzrawAqMjQDA@mail.gmail.com> (raw)
In-Reply-To: <20200322171216.3260cd37@archlinux>

On Sun, Mar 22, 2020 at 7:14 PM Jonathan Cameron <jic23@kernel.org> wrote:
> On Tue, 17 Mar 2020 12:18:09 +0200
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
>
> > With DEBUG_SHIRQ enabled we have a kernel crash
> >
> > [  116.482696] BUG: kernel NULL pointer dereference, address: 0000000000000000
> >
> > ...
> >
> > [  116.606571] Call Trace:
> > [  116.609023]  <IRQ>
> > [  116.611047]  complete+0x34/0x50
> > [  116.614206]  bmp085_eoc_irq+0x9/0x10 [bmp280]
> >
> > because DEBUG_SHIRQ mechanism fires an IRQ before registration and drivers
> > ought to be able to handle an interrupt happening before request_irq() returns.
> >
> > Fixes: aae953949651 ("iio: pressure: bmp280: add support for BMP085 EOC interrupt")
> > Cc: Linus Walleij <linus.walleij@linaro.org>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>
> Hmm. Nasty corner case but fair enough to fix it up.
> I guess we should audit other drivers for similar paths...

One can easily test, no device even needed (however in this case I have one)

...

> > -     if (data->use_eoc)
> > -             init_completion(&data->done);
> > +     reinit_completion(&data->done);
>
> reinit on the completion when we don't even have an interrupt
> (hence data->use_eoc == false) seems excessive.  Why did
> you drop the conditional?

It's harmless and gives less code I believe.
But if you insist I can put it back.

-- 
With Best Regards,
Andy Shevchenko

  reply	other threads:[~2020-03-22 21:15 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-17 10:18 [PATCH v1 1/5] iio: pressure: bmp280: Tolerate IRQ before registering Andy Shevchenko
2020-03-17 10:18 ` [PATCH v1 2/5] iio: pressure: bmp280: Use IIO_DEVICE_ATTR_RO macro Andy Shevchenko
2020-03-22 17:16   ` Jonathan Cameron
2020-03-22 21:17     ` Andy Shevchenko
2020-03-23  9:38       ` Jonathan Cameron
2020-03-17 10:18 ` [PATCH v1 3/5] iio: pressure: bmp280: Explicitly mark GPIO optional Andy Shevchenko
2020-03-17 10:18 ` [PATCH v1 4/5] iio: pressure: bmp280: Drop unneeded explicit castings Andy Shevchenko
2020-03-22 17:21   ` Jonathan Cameron
2020-03-22 21:20     ` Andy Shevchenko
2020-03-17 10:18 ` [PATCH v1 5/5] iio: pressure: bmp280: Join string literals back Andy Shevchenko
2020-03-22 17:12 ` [PATCH v1 1/5] iio: pressure: bmp280: Tolerate IRQ before registering Jonathan Cameron
2020-03-22 21:15   ` Andy Shevchenko [this message]
2020-03-23  9:40     ` Jonathan Cameron
2020-03-23 10:08       ` Andy Shevchenko

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