Re: [PATCH 3/3] tty: n_hdlc: fix read() hangup check

[sashiko-bot@kernel.org]

> When a tty is hung up, the file ops are generally set to
> hung_up_tty_fops, but this is not the case for, for example,
> /dev/console.
> 
> Make sure to check the TTY_HUPPING flag so that a hangup is detected and
> read() returns zero also with /dev/console (as is done for n_tty [1]).
> 
> Note that before commit c96cf923a98d ("tty: Don't block on IO when ldisc
> change is pending") a task hanging up the tty would get stuck in
> uninterruptible sleep when there are blocked readers, but since then
> read() incorrectly returns -EAGAIN instead.
> 
> The false-positive stuck hangup issue was flagged by an LLM.
> 
> [1] 28b0f8a6962a ("tty: make n_tty_read() always abort if hangup is in progress")
> 
> Fixes: 1035b63d3c6f ("n_hdlc: fix read and write locking")
> Cc: stable@vger.kernel.org	# 2.6.38
> Signed-off-by: Johan Hovold <johan@kernel.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261028132049.728457-1-johan@kernel.org?part=3