linux-kernel - Re: [PATCH v2] staging: axis-fifo: fix sleep while holding mutex

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Message-ID: <CAMp7ucpoyXDWM=xndZTEc7H1OJSH6sJO2qFLYsux6iwSTHu-aQ@mail.gmail.com>
Date: Tue, 3 Feb 2026 16:44:11 +0300
From: Baran Arda <baran9arda@...il.com>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: ovidiu.panait.oss@...il.com, gshahrouzi@...il.com, 
	linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: axis-fifo: fix sleep while holding mutex

Hi Greg,
I didnt think there was an issue, I thought I identified a pattern and
wanted to improve speed with this update.

This was just compile tested. I didnt realize it would create a _race
condition_.

I occasionally review staging drivers for cleanup opportunities for
learning linux kernel. I do not have access to this driver.

best regards,
Baran Arda

Greg KH <gregkh@...uxfoundation.org>, 3 Şub 2026 Sal, 15:02 tarihinde
şunu yazdı:
>
> On Tue, Feb 03, 2026 at 02:48:58PM +0300, Baran Arda wrote:
> > The driver calls wait_event_interruptible_timeout() while holding a mutex. This can lead to a deadlock or poor performance as the mutex is held while the process is sleeping, preventing other processes from accessing the device. This patch moves the wait_event call outside of the mutex lock in both read and write operations.
>
> What kind of tool was used to "find and fix" this "issue"?
>
> And how was this tested?
>
> And are you _sure_ it is correct?  (hint, I think you just broke the
> driver's logic, please look closely at your patch...)
>
> And what caused you to want to make this change to this driver?  Do you
> have access to this hardware?
>
> thanks,
>
> greg k-h