From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Guenter Roeck <linux@roeck-us.net>,
Clark Williams <clrkwllms@kernel.org>,
linux-rt-devel@lists.linux.dev,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: possible circular locking dependency backtrace seen when enabling PREEMPT_RT
Date: Wed, 12 Feb 2025 18:21:52 +0100 [thread overview]
Message-ID: <20250212172152.6f66lcrk@linutronix.de> (raw)
In-Reply-To: <20250212120706.7e169c2b@gandalf.local.home>
On 2025-02-12 12:07:06 [-0500], Steven Rostedt wrote:
>
> Expanding on my argument. Why does it work for non-PREEMPT_RT but not for
> PREEMPT_RT?
The semantics are different. It is not a race on !RT but *might* happen
on RT.
The other alternative would be to add additional locking into
pcnet32_access() and avoid having the lock in the ISR.
But this driver/ hardware is old and probably hardly used outside of
qemu. We did not have any reports about this recently. We had a few
reports within the net stack but this is gone now.
So. Adding your suggestion into the core code just to satisfy one driver
is not something I had in mind.
> -- Steve
Sebastian
next prev parent reply other threads:[~2025-02-12 17:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-12 15:56 possible circular locking dependency backtrace seen when enabling PREEMPT_RT Guenter Roeck
2025-02-12 16:45 ` Steven Rostedt
2025-02-12 16:59 ` Sebastian Andrzej Siewior
2025-02-12 17:03 ` Steven Rostedt
2025-02-12 17:07 ` Steven Rostedt
2025-02-12 17:21 ` Sebastian Andrzej Siewior [this message]
2025-02-12 17:09 ` Sebastian Andrzej Siewior
2025-02-12 17:18 ` Steven Rostedt
2025-02-12 17:24 ` Sebastian Andrzej Siewior
2025-02-12 17:33 ` Steven Rostedt
2025-02-13 8:38 ` Sebastian Andrzej Siewior
2025-02-12 17:54 ` Guenter Roeck
2025-02-12 18:17 ` Steven Rostedt
2025-02-12 16:56 ` Sebastian Andrzej Siewior
2025-02-12 18:36 ` Guenter Roeck
2025-02-13 8:28 ` Sebastian Andrzej Siewior
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