linux-kernel - Re: [PATCH v4 2/2] PCI/aer_inject: Convert inject_lock to raw_spinlock

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Message-ID: <20251103200253.SlYC8MU7@linutronix.de>
Date: Mon, 3 Nov 2025 21:02:53 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Guangbo Cui <jckeep.cuiguangbo@...il.com>,
	Clark Williams <clrkwllms@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Waiman Long <longman@...hat.com>, linux-rt-devel@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v4 2/2] PCI/aer_inject: Convert inject_lock to
 raw_spinlock_t

On 2025-11-03 20:21:20 [+0100], Peter Zijlstra wrote:
> On Sun, Nov 02, 2025 at 10:57:06AM +0000, Guangbo Cui wrote:
> > The AER injection path may run in interrupt-disabled context while
> > holding inject_lock. On PREEMPT_RT kernels, spinlock_t becomes a
> > sleeping lock, so it must not be taken while a raw_spinlock_t is held.
> > Doing so violates lock ordering rules and trigger lockdep reports
> > such as “Invalid wait context”.
> > 
> > Convert inject_lock to raw_spinlock_t to ensure non-sleeping locking
> > semantics. The protected list is bounded and used only for debugging,
> > so raw locking will not cause latency issues.
> 
> Bounded how?

I think I used the term "not bounded" and said "it does not matter
because it is debugging only". Best would be to leave that part and use
only "only for debugging".

> Also,

Sebastian