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From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Rik van Riel <riel@surriel.com>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	 kernel-team@meta.com
Subject: Re: [PATCH] input/evdev: move kill_fasync() outside buffer_lock to fix SOFTIRQ deadlock
Date: Wed, 13 May 2026 13:01:58 -0700	[thread overview]
Message-ID: <agTXYr_fFGiJ7lAe@google.com> (raw)
In-Reply-To: <20260513115000.77ec5975@fangorn>

Hi Rik,

On Wed, May 13, 2026 at 11:50:00AM -0400, Rik van Riel wrote:
> buffer_lock is a SOFTIRQ-safe spinlock. kill_fasync() acquires fa_lock
> (SOFTIRQ-unsafe), creating a potential SOFTIRQ-safe->SOFTIRQ-unsafe lock
> ordering violation that lockdep flags as a deadlock.
> 
> Fix by moving the kill_fasync() call to evdev_pass_values() after
> buffer_lock is released, alongside the existing wake_up_interruptible_poll().
> 
> The wakeup condition check is the same in __pass_event() and
> evdev_pass_values()

Does this really fix anything? This code is running holding
input->event_lock with IRQs off...

Thanks.

-- 
Dmitry

  reply	other threads:[~2026-05-13 20:02 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-13 15:50 [PATCH] input/evdev: move kill_fasync() outside buffer_lock to fix SOFTIRQ deadlock Rik van Riel
2026-05-13 20:01 ` Dmitry Torokhov [this message]
2026-05-14 13:06   ` Rik van Riel
2026-05-14  7:06 ` sashiko-bot

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