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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ZY62ca9F; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 235F2606A31A; Tue, 27 Oct 2026 06:09:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ZY62ca9F Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C75C1F01825; Tue, 27 Oct 2026 06:09:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793081349; bh=PvUfohqTveZnoV3DgFtksSsIE02EL0Iiz/+3F4CWDFk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ZY62ca9FjdH0FUeYesY6VkwRjc+4tmxUFt0orOxyEXsd2joZPCANqPk2eZR7MseYl S8jLo+ASnLYPll5PcE7izn+lKIMotVAEiPe0Sr4iUJM3115VYr+2rBc7Y2ZELbwLhV GBWwgH+UPmjiDEZIJzvs5wxfG/gcxmOdRS/WpqRJSPQOy+8tHK5EnC7tm/DgFK7U5G pB8dRRp5oi9b7OzppcZ9SaNQdsOOB7z4BFEpsaLOjMhcz3h3eBdOwLSXjz61k0QY12 PYHDQCkFMnMvA2AgQozqJ5NmIW3N2v2Wqnq4y8GWRXC0mYAVxfBJttA1HFgaloaFze dTLE02M93gWlQ== Message-ID: <53624662-e94e-4fcb-9902-7fa4143c7689@kernel.org> Date: Tue, 27 Oct 2026 07:09:05 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] serial: 8250: clear RX trigger callbacks when removing a port To: James Hilliard , Greg Kroah-Hartman , Crescent Hsieh Cc: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , Andy Shevchenko , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261024-submit-serial-8250-rxtrig-lifetime-v1-v1-1-731b78d5003d@gmail.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 24. 10. 26, 22:05, James Hilliard wrote: > serial8250_unregister_port() removes the device supplied by a driver and > normally re-registers the persistent slot as an unknown legacy port. The > slot retains its RX trigger callbacks and sysfs attribute group, so the > replacement rx_trig_bytes attribute can still call the removed driver's > code. Unloading that driver leaves the callbacks pointing into freed > module text. > > Clear both callbacks after uart_remove_one_port() has drained the old > sysfs users and before registering the fallback port. Its RX trigger > attribute then uses the generic handlers, which reject a port without > FIFO capabilities. > > Also copy the callbacks unconditionally during registration. A replacement > port without custom handlers must use the generic implementation instead > of inheriting callbacks from the previous owner of the slot. I don't understand why this is a problem only for the two callbacks. Care to elaborate? > Fixes: 8a6c543cf8b3 ("serial: 8250: allow UART drivers to override rx_trig_bytes handling") > Signed-off-by: James Hilliard > --- > drivers/tty/serial/8250/8250_core.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c > index 42319843cb5b..c638e10c43e2 100644 > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -830,10 +830,8 @@ static int __serial8250_register_8250_port(struct uart_8250_port *uart, > uart->port.get_divisor = up->port.get_divisor; > if (up->port.set_divisor) > uart->port.set_divisor = up->port.set_divisor; > - if (up->port.get_rxtrig) > - uart->port.get_rxtrig = up->port.get_rxtrig; > - if (up->port.set_rxtrig) > - uart->port.set_rxtrig = up->port.set_rxtrig; > + uart->port.get_rxtrig = up->port.get_rxtrig; > + uart->port.set_rxtrig = up->port.set_rxtrig; > if (up->port.startup) > uart->port.startup = up->port.startup; > if (up->port.shutdown) > @@ -953,6 +951,9 @@ void serial8250_unregister_port(struct uart_8250_port *uart) > } > > uart_remove_one_port(&serial8250_reg, &uart->port); > + /* The fallback port must use the generic RX trigger handlers. */ > + uart->port.get_rxtrig = NULL; > + uart->port.set_rxtrig = NULL; > if (serial8250_isa_devs) { > uart->port.flags &= ~UPF_BOOT_AUTOCONF; > uart->port.type = PORT_UNKNOWN; thanks, -- js suse labs