Re: Regression in inv_mpu6050: 4.6.0-rc5

From: Jonathan Cameron <jic23@jic23.retrosnub.co.uk>
To: Greg KH <gregkh@linuxfoundation.org>,
	Jonathan Cameron <jic23@kernel.org>
Cc: Crestez Dan Leonard <cdleonard@gmail.com>,
	One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
	Michael Welling <mwelling@ieee.org>,
	mranostay@gmail.com, linux-kernel@vger.kernel.org,
	daniel.baluta@intel.com, linux-iio@vger.kernel.org
Subject: Re: Regression in inv_mpu6050: 4.6.0-rc5
Date: Wed, 04 May 2016 19:15:34 +0100	[thread overview]
Message-ID: <3501B085-798A-409C-8055-1FD4DD5019D3@jic23.retrosnub.co.uk> (raw)
In-Reply-To: <20160504172443.GA27422@kroah.com>

On 4 May 2016 18:24:43 BST, Greg KH <gregkh@linuxfoundation.org> wrote:
>On Wed, May 04, 2016 at 08:49:06AM +0100, Jonathan Cameron wrote:
>> On 03/05/16 19:54, Crestez Dan Leonard wrote:
>> > On 05/01/2016 10:58 PM, Jonathan Cameron wrote:
>> >> On 27/04/16 16:56, One Thousand Gnomes wrote:
>> >>> On Tue, 26 Apr 2016 18:07:55 -0500
>> >>> Michael Welling <mwelling@ieee.org> wrote:
>> >>>
>> >>>> On Tue, Apr 26, 2016 at 11:26:51PM +0100, One Thousand Gnomes
>wrote:
>> >>>>>
>> >>>>> This now causes us to crash and burn on the ASUS T100TA
>Baytrail/T
>> >>>>> platforms
>> >>>>>  
>> >>>>
>> >>>> I believe this regression has already been patched.
>> >>>>
>> >>>> Check the latest commits in linux-next.
>> >>>>
>> >>>>
>https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/log/drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c
>> >>>>
>> >>>> See if the latest patches fix your issue.
>> >>>
>> >>> It does - as this is a regression can we please get those fixes
>into the
>> >>> next -rc ?
>> >>>
>> >> I'm afraid I'm lost in this one - which patch caused the
>regression and
>> >> which one fixed it?  The only patches I can immediately see in
>next
>> >> both introduce and then squish a similar bug, but neither of them
>> >> has hit Linus' tree yet.
>> >>
>> >> Or are we dealing with what was fixed in:
>> >> c816d9e7 iio: imu: mpu6050: fix possible NULL dereferences
>> >> I had understood that one as more hypothetical than real...
>> >>
>> >> Unfortunately I'm travelling and I suspect that means this will
>only get
>> >> in just after the release (so for 4.6.1) once I've confirmed which
>fixes
>> >> we actually need to backport.
>> >>
>> > Commit
>> >     c816d9e7: iio: imu: mpu6050: fix possible NULL dereferences
>> > Fixes:
>> >     33da559f: iio: imu: mpu6050: add mpu6500 register settings
>> > 
>> > As far as I can tell this crash will always happen when the device
>is
>> > probed via ACPI.
>> 
>> Hi Greg,
>> 
>> A quick heads up.
>> 
>> Unfortunately this regression has come up whilst I'm travelling and
>> don't have appropriate signing keys with me to do a pull request.
>> Should be able to do one tomorrow evening as I'll back home.
>> 
>> Turns out the 'possible' is quite common and causing a mess.
>> Even better the fix actually has a fix as well... 
>> 
>> Fastest option is probably a cherry pick of:
>> 
>> c816d9e7: iio: imu: mpu6050: fix possible NULL dereferences
>> 718ba46e: iio: imu: mpu6050: Fix name/chip_id when using ACPI
>
>From where?
Doh.

Both already in your staging-next. Confusion was over the seriousness of the issue so went via wrong route.

>
>> 
>> I'll send you a pull request of my 
>> togreg-in-a-hurry branch tomorrow.
>> 
>> Sorry for these being so late in the cycle.
>> 
>> Anyhow, run for train time. 
>
>You can always just send me patches, no need for it to always be a pull
>request if you can't do that for some reason.

Good point, nothing like limited time to make one an idiot sometimes!

Jonathan
>
>thanks,
>
>greg k-h

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