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Thu, 05 Mar 2026 08:49:10 -0800 (PST) Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.400.21\)) Subject: Re: [net,v4] serial: caif: hold tty->link reference in ldisc_open and ser_release From: Shuangpeng In-Reply-To: <20260304173956.0081d8ea@kernel.org> Date: Thu, 5 Mar 2026 11:48:59 -0500 Cc: davem@davemloft.net, edumazet@google.com, linux-kernel@vger.kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, horms@kernel.org, jiayuan.chen@shopee.com, jirislaby@kernel.org, andrew+netdev@lunn.ch, gregkh@linuxfoundation.org, shaojijie@huawei.com Content-Transfer-Encoding: quoted-printable Message-Id: <951CE2C2-6B03-4EA2-B4AE-D78A47EFC75E@gmail.com> References: <20260301220525.1546355-1-shuangpeng.kernel@gmail.com> <20260304012612.2592839-1-kuba@kernel.org> <20260304173956.0081d8ea@kernel.org> To: Jakub Kicinski X-Mailer: Apple Mail (2.3864.400.21) > On Mar 4, 2026, at 20:39, Jakub Kicinski wrote: >=20 > On Wed, 4 Mar 2026 20:23:20 -0500 Shuangpeng wrote: >>> Can this dereference NULL? The tty->link field is only set for PTY >>> (pseudo-terminal) pairs. For regular serial ports and other non-PTY >>> devices, tty->link is NULL. >>>=20 >>> The CAIF line discipline can be attached to any TTY device via the >>> TIOCSETD ioctl. When ser_release() is called to clean up a = ser_device >>> that was created for a non-PTY TTY device, tty->link would be NULL. >>>=20 >>> Should this check for NULL before calling tty_kref_put()? >>>=20 >>=20 >> tty_kref_get() / tty_kref_put() are NULL-safe, so calling them with >> tty->link =3D=3D NULL is not a functional issue. >>=20 >> I can add explicit if (tty->link) guards to improve readability if = you prefer. >=20 > Sorry, I should have checked, I'm surprised the AI agent got something > this basic wrong. Just the Fixes tag, then.. Thanks for confirming. If there are no other concerns, I'll update the = Fixes=20 tag and send the final version.=