[PATCH v3][for 4.15] dmaengine: dmatest: move callback wait queue to thread context

[Dan Williams]

On Fri, Nov 17, 2017 at 9:17 AM, Adam Wallis <awallis at codeaurora.org> wrote:
> On 11/17/2017 12:01 PM, Adam Wallis wrote:
>> On 11/17/2017 10:57 AM, Dan Williams wrote:
>>> On Fri, Nov 17, 2017 at 7:28 AM, Adam Wallis <awallis at codeaurora.org> wrote:
>>>> On 11/17/2017 10:12 AM, Dan Williams wrote:
>>>>> On Fri, Nov 17, 2017 at 6:11 AM, Adam Wallis <awallis at codeaurora.org> wrote:
>>>>>> Commit adfa543e7314 ("dmatest: don't use set_freezable_with_signal()")
>>>>>> introduced a bug (that is in fact documented by the patch commit text)
>>>>>> that leaves behind a dangling pointer. Since the done_wait structure is
>>>>>> allocated on the stack, future invocations to the DMATEST can produce
>>>>>> undesirable results (e.g., corrupted spinlocks).
>>>>>>
>>>>>> Commit a9df21e34b42 ("dmaengine: dmatest: warn user when dma test times
>>>>>> out") attempted to WARN the user that the stack was likely corrupted but
>>>>>> did not fix the actual issue.
>>>>>>
>>>>>> This patch fixes the issue by pushing the wait queue and callback
>>>>>> structs into the the thread structure. If a failure occurs due to time,
>>>>>> dmaengine_terminate_all will force the callback to safely call
>>>>>> wake_up_all() without possibility of using a freed pointer.
>>>>>>
>>>>>> Cc: stable at vger.kernel.org # 4.13.x: a9df21e: dmatest: Warn User
>>>>>> Cc: stable at vger.kernel.org # 4.13.x
>>>>>> Cc: stable at vger.kernel.org # 4.14.x
>>>>>
>>>>
>>>> Sure - do you want me to remove them? I was just following the instructions on
>>>> stable.
>>>
>>> It's not broken, just a note for next time.
>>>
> One last question - if all we need is Fixes and CC stable...how do we indicate a
> dependency (for a cherry pick)?

For cherry picks the document does say to include multiple "Cc:
stable" lines. So ignore what I said you're following the proper
process.

The way I've handled this is to just wait for the -stable team to
notify that the patch does not apply and send a custom backport at
that point.