Re: [PATCH net-next] 6pack: drop redundant locking and refcounting

[Dan Carpenter <dan.carpenter@linaro.org>]

On Tue, Sep 23, 2025 at 02:07:06PM +0800, Qingfang Deng wrote:
> The TTY layer already serializes line discipline operations with
> tty->ldisc_sem, so the extra disc_data_lock and refcnt in 6pack
> are unnecessary.
> 
> Removing them simplifies the code and also resolves a lockdep warning
> reported by syzbot. The warning did not indicate a real deadlock, since
> the write-side lock was only taken in process context with hardirqs
> disabled.
> 
> Reported-by: syzbot+5fd749c74105b0e1b302@syzkaller.appspotmail.com
> Signed-off-by: Qingfang Deng <dqfext@gmail.com>

checkpatch says:

WARNING: Reported-by: should be immediately followed by Closes: with a URL to the report

Which is relevant here because Google has apparently deleted their
search button and is only displaying the AI button.  "The email address
syzbot+5fd749c74105b0e1b302@syzkaller.appspotmail.com is an automated
sender used by ..."  Thanks, AI!  I can still press enter to do a Google
search but there are no results with syzbot ID.

I can't find a search button on the syzbot website.

Ah.  Let's check lore.  Hooray!  How did we ever survive before lore?
https://lore.kernel.org/all/000000000000e8231f0601095c8e@google.com/

Please add the Closes tag and resend.  Otherwise it looks good.  Thanks!

This code was copy and pasted from drivers/net/ppp/ppp_synctty.c btw so
that's a similar thing if anyone wants to fix that.

KTODO: remove sp_get/put() from ppp_synctty.c

regards,
dan carpenter