linux-kernel - Re: [PATCH v2 1/2] gpiolib: cdev: Fix &lr->wait.lock deadlock issue

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Message-ID: <ZJlwG4zzmm4ArMNX@smile.fi.intel.com>
Date:   Mon, 26 Jun 2023 14:01:47 +0300
From:   "andy@...nel.org" <andy@...nel.org>
To:     YE Chengfeng <cyeaa@...nect.ust.hk>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] gpiolib: cdev: Fix &lr->wait.lock deadlock issue

On Mon, Jun 26, 2023 at 10:39:56AM +0000, YE Chengfeng wrote:
> linereq_put_event is called from both interrupt context (e.g.,
> edge_irq_thread) and process context (process_hw_ts_thread).
> Therefore, interrupt should be disabled before acquiring lock
> &lr->wait.lock inside linereq_put_event to avoid deadlock when
> the lock is held in process context and edge_irq_thread comes.
> 
> Similarly, linereq_read_unlocked running in process context
> also acquies the same lock. It also need to disable interrupt
> otherwise deadlock could happen if the irq edge_irq_thread
> comes to execution while the lock is held.
> 
> Fix the two potential deadlock issues by spin_lock_bh() and
> spin_lock_irq() separately.

Side note: You have two patches in something that seems to be the series,
but lacks the references in email headers. Whenever you send a series,
do not forget to add --thread to `git send-email`.

-- 
With Best Regards,
Andy Shevchenko