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From: Ferry Toth <fntoth@gmail.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ferry Toth <ftoth@exalondelft.nl>
Cc: Ruslan Bilovol <ruslan.bilovol@gmail.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
	Pawel Laszczak <pawell@cadence.com>,
	Felipe Balbi <balbi@kernel.org>, Jack Pham <jackp@codeaurora.org>,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-doc@vger.kernel.org, Lorenzo Colitti <lorenzo@google.com>,
	Wesley Cheng <wcheng@codeaurora.org>,
	robh+dt@kernel.org, agross@kernel.org,
	bjorn.andersson@linaro.org, frowand.list@gmail.com,
	devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	heikki.krogerus@linux.intel.com,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Pavel Hofman <pavel.hofman@ivitera.com>
Subject: Re: [PATCH v2 1/3] Revert "usb: gadget: u_audio: add real feedback implementation"
Date: Fri, 27 Aug 2021 22:41:05 +0200	[thread overview]
Message-ID: <605f5ae5-365d-80be-42a4-8d273a20c3d7@gmail.com> (raw)
In-Reply-To: <YSiiTrW/ZF2PyGWd@kroah.com>

Op 27-08-2021 om 10:29 schreef Greg Kroah-Hartman:
> On Thu, Aug 26, 2021 at 08:57:37PM +0200, Ferry Toth wrote:
>> This reverts commit e89bb4288378b85c82212b60dc98ecda6b3d3a70.
>>
>> The commit is part of a series with commit
>> 24f779dac8f3efb9629adc0e486914d93dc45517 causing a BUG on dwc3
>> hardware, at least on Intel Merrifield platform when configured
>> through configfs:
>> BUG: kernel NULL pointer dereference, address: 0000000000000008
>> ...
>> RIP: 0010:dwc3_gadget_del_and_unmap_request+0x19/0xe0
>> ...
>> Call Trace:
>>   dwc3_remove_requests.constprop.0+0x12f/0x170
>>   __dwc3_gadget_ep_disable+0x7a/0x160
>>   dwc3_gadget_ep_disable+0x3d/0xd0
>>   usb_ep_disable+0x1c/0x70
>>   u_audio_stop_capture+0x79/0x120 [u_audio]
>>   afunc_set_alt+0x73/0x80 [usb_f_uac2]
>>   composite_setup+0x224/0x1b90 [libcomposite]
>>
>> Pavel's suggestion to add
>> `echo "adaptive" > functions/uac2.usb0/c_sync` to the configfs script
>> resolves the issue.
>> Thinh suggests "the crash is probably because of f_uac2 prematurely
>> freeing feedback request before its completion. usb_ep_dequeue() is
>> asynchronous. dwc2() may treat it as a synchronous call so you didn't
>> get a crash."
>>
>> Revert as this is a regression and the kernel shouldn't crash depending
>> on configuration parameters.
> 
> Are these normal configuration options in the wild, or is this just
> something that you "can do"?

It's a work around suggested by Pavel, a line that can be added to 
configfs script.

>> Signed-off-by: Ferry Toth <ftoth@exalondelft.nl>
> 
> I need an ack from the original authors to revert all this...

A fix has appeared:
https://lore.kernel.org/linux-usb/1jfsuvw817.fsf@starbuckisacylon.baylibre.com/T/#m922149b7e74204c8ed1bed2c624910ab4eafd43c

This has been acked by Felipe. If we can get that in 5.14.0 it would be 
preferable to reverting this series.

> thanks,
> 
> greg k-h
> 


  reply	other threads:[~2021-08-27 20:41 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 18:57 [PATCH v2 0/3] Revert "usb: gadget: u_audio: add real feedback implementation" Ferry Toth
2021-08-26 18:57 ` [PATCH v2 1/3] " Ferry Toth
2021-08-27  8:29   ` Greg Kroah-Hartman
2021-08-27 20:41     ` Ferry Toth [this message]
2021-08-26 18:57 ` [PATCH v2 2/3] Revert "usb: gadget: f_uac2: add adaptive sync support for capture" Ferry Toth
2021-08-26 18:57 ` [PATCH v2 3/3] Revert "usb: gadget: f_uac2/u_audio: add feedback endpoint support" Ferry Toth
2021-08-27  7:59 ` [PATCH v2 0/3] Revert "usb: gadget: u_audio: add real feedback implementation" Jerome Brunet
2021-08-27  9:15   ` Andy Shevchenko
2021-08-27 20:44     ` Ferry Toth
2021-08-27  8:27 ` Greg Kroah-Hartman
2021-08-27 20:49   ` Ferry Toth

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