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Date: Mon, 22 Jun 2026 08:56:40 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Runyu Xiao <runyu.xiao@seu.edu.cn>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>, "David S. Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
 stable@vger.kernel.org
Subject: Re: [PATCH net] net: au1000: move free_irq out of the close-time
 spinlocked section
Message-ID: <20260622085640.14e0018f@kernel.org>
In-Reply-To: <20260619151816.1144289-1-runyu.xiao@seu.edu.cn>
References: <20260619151816.1144289-1-runyu.xiao@seu.edu.cn>
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On Fri, 19 Jun 2026 23:18:16 +0800 Runyu Xiao wrote:
> au1000_close() calls free_irq() while aup->lock is still held with
> spin_lock_irqsave(). free_irq() can sleep because it takes the IRQ
> descriptor request mutex, so it does not belong inside the close-time
> spinlocked section.
> 
> This was found by our static analysis tool and then confirmed by manual
> review of the in-tree au1000_close() .ndo_stop path. The reviewed path
> keeps aup->lock held across the MAC reset, queue stop and
> free_irq(dev->irq, dev).
> 
> A directed runtime validation kept that ndo_stop carrier and the same
> free_irq(dev->irq, dev) operation under the driver lock. Lockdep reported
> "BUG: sleeping function called from invalid context" and "Invalid wait
> context" while free_irq() was taking desc->request_mutex, with
> au1000_close() and free_irq() on the stack.
> 
> Drop aup->lock before freeing the IRQ. The protected close-time work still
> stops the device and queue before IRQ teardown, but the sleepable IRQ core
> path now runs outside the spinlocked section.

Do you really think that this bug matters if nobody fixed it on
a 20+ year old platform?

Please do not point your AI scanning tools at old code!
The patch is valid I guess but we have heaps of bugs like this
that _nobody care about in practice_! You're wasting everyone's
time.