Re: [PATCH v2] tty: pty: preserve open slaves after rejected locked open

[sashiko-bot@kernel.org]

> Opening a locked PTY slave fails with EIO, but the failure path sets
> TTY_IO_ERROR on the shared slave tty. Previously opened slave files then
> fail I/O even though their master is still open.
> 
> tty_open() releases a file after the slave open callback fails. Merely
> skipping TTY_IO_ERROR on the rejected open is insufficient: pty_close()
> can mistake the failed file for the last slave and close the master.
> Counting tty references is also insufficient because a real last close
> can race the failed open and its release.
> 
> Track which slave files opened successfully. Ignore failed files during
> close, and mark the master peer closed only when the last successful
> slave file closes. In-kernel callers may pass NULL instead of a file;
> retain the count-based close behavior for those callers. A selftest
> checks locked opens with zero, one, and two existing slave files, plus
> ordinary last-slave close behavior.
> 
> Fixes: 699390354da6 ("pty: Ignore slave pty close() if never successfully opened")
> Assisted-by: LLM
> Signed-off-by: Akira Patafio <kokokoala4211@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261002202455.25324-1-kokokoala4211@gmail.com?part=1