Re: [PATCH] mtd: spi-nor: scope the exclusive RWW lock

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello,

On 10/08/2026 at 10:25:28 +02, "Michael Walle" <mwalle@kernel.org> wrote:

> On Sun Aug 9, 2026 at 10:42 AM CEST, Runyu Xiao wrote:
>> spi_nor_rww_start_exclusive() is used as a wait_event_killable()
>> condition. The raw mutex_lock() leaves nor->lock held when the busy
>> condition returns false, so the waiter can block the active operation that
>> must clear the RWW state.
>>
>> Use the same scoped mutex guard as the other RWW start helpers so the
>> mutex is released on both the busy and successful condition paths. The
>> state flags remain the handoff to the caller, while
>> spi_nor_rww_end_exclusive() continues
>> to acquire the mutex when clearing them.
>>
>> The change was checked by comparing the original and patched source.
>
> What do you mean? Was this AI assisted?
>
>> A source-level check of the original wait condition found that it takes
>> `nor->lock` and returns false while an RWW operation is still active. The
>> patched source was checked for a scoped mutex guard that releases
>> `nor->lock` before the wait condition returns. A user-space pthread model
>> held `nor->lock` on the false-condition path and showed that the
>> operation-ending path then blocks when it needs the same mutex. No live
>> SPI-NOR test was run.
>
> What do you mean by "user-space pthread model"? Ported this into
> user-space and tried it there? Please keep the commit message
> precise and don't use any AI gibberish. Please, explain what's going
> on with your own sentences. That way, it shows at least some
> understanding what you are trying to change here.
>
> That being said, there is something odd about that commit. Tudor, do
> you know why you've omitted the guard() in
> spi_nor_rww_start_exclusive()?

I agree with Michael, the fix looks legitimate, however the commit log
is unreadable and should be a 3-line straightforward paragraph.

Thanks,
Miquèl

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