From: sashiko-bot@kernel.org
To: "Weidong Wang" <weidongw@illinois.edu>
Cc: linux-serial@vger.kernel.org
Subject: Re: [PATCH] serial: 8250_pci: don't re-enable an enabled device on resume
Date: Thu, 12 Nov 2026 07:16:55 +0000 [thread overview]
Message-ID: <sashiko-outbox-210581@kernel.org> (raw)
In-Reply-To: <20261112-c3-n108-v1-1-d48f8da5894e@illinois.edu>
> From: Weidong Wang <weidongw@illinois.edu>
>
> pciserial_resume_one() calls pci_enable_device() on every resume. Probe
> already enabled the device with pcim_enable_device() and suspend does
> not disable it, so each suspend/resume cycle adds one to enable_cnt
> that nothing drops. After N cycles, unbinding the driver leaves
> enable_cnt at N and the device enabled.
>
> Only re-enable the device when it is actually disabled.
>
> Found by an AI code review agent (an LLM-based bug-finding tool
> developed by Zijie Zhao and the submitter) and confirmed on an
> unmodified kernel, without error injection, on x86_64 under QEMU with
> the "pci-serial" device (1b36:0002), which 8250_pci drives: after five
> s2idle cycles with pm_test=devices, /sys/bus/pci/devices/.../enable
> read 6, and 5 after unbinding the driver; without the suspend
> cycles it read 1, and 0 after unbinding.
>
> With this patch it stays at 1 across the cycles and drops to 0 on
> unbind.
>
> The reproducer, fix and changelog were drafted with AI assistance
> (Claude), then reviewed and tested by the submitter.
>
> Cc: Zijie Zhao <zijie4@illinois.edu>
> Signed-off-by: Weidong Wang <weidongw@illinois.edu>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261112-c3-n108-v1-1-d48f8da5894e@illinois.edu?part=1
prev parent reply other threads:[~2026-11-12 7:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-12 7:07 [PATCH] serial: 8250_pci: don't re-enable an enabled device on resume Weidong Wang
2026-11-12 7:07 ` Weidong Wang via B4 Relay
2026-11-12 7:16 ` sashiko-bot [this message]
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