Re: [PATCH] mhi: Fix double dma free

[Bhaumik Bhatt <bbhatt@codeaurora.org>]

On 2021-02-09 08:06 AM, Loic Poulain wrote:
> On Tue, 9 Feb 2021 at 16:55, Jeffrey Hugo <jhugo@codeaurora.org> wrote:
>> 
>> On 2/9/2021 8:53 AM, Loic Poulain wrote:
>> > mhi_deinit_chan_ctxt functionthat takes care of unitializing channel
>> > resources, including unmapping coherent MHI areas, can be called
>> > from different path in case of controller unregistering/removal:
>> >   - From a client driver remove callback, via mhi_unprepare_channel
>> >   - From mhi_driver_remove that unitialize all channels
>> >
>> > mhi_driver_remove()
>> > |-> driver->remove()
>> > |    |-> mhi_unprepare_channel()
>> > |        |-> mhi_deinit_chan_ctxt()
>> > |...
>> > |-> mhi_deinit_chan_ctxt()
>> >
>> > This leads to double dma freeing...
>> >
>> > Fix that by preventing deinit for already uninitialized channel.
>> >
>> > Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
>> > Reported-by: Kalle Valo <kvalo@codeaurora.org>
>> > ---
>> 
>> Seems like this should have a Fixes: tag, no?
> 
> Right, thanks, i'll add it in V2 once I get feedback.

Hi Loic, Mani,

I saw this same issue a while back but could not collect the logs for 
it.

I had already pushed a patch to fix this differently [1] which was 
recently reviewed by Hemant.

Although there wasn't a purposeful fixes tag for it. I think the culprit 
for this issue is [2]:

As it allows the unprepare to go through on remove(), which was 
traditionally not allowed and
ends up uncovering this issue as it fixes another.

Channel updates [3] address that and provide a bunch of other 
improvements. Please consider them.

Thanks,
Bhaumik

[1] https://lkml.org/lkml/2021/2/4/1161
[2] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/bus/mhi?h=v5.11-rc7&id=a7f422f2f89e7d48aa66e6488444a4c7f01269d5
[3] https://lkml.org/lkml/2021/2/4/1155

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