From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F259372B3E; Fri, 23 Jan 2026 05:55:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769147720; cv=none; b=kV5rgt1MTsv2ugYIuCJUfNEqUTv0YcDKiUQSXcwmhjvrainz1uIKzfR+ML7UmyP5jzJgKei3tlRUaPpWWDuC2IyREkhRy0Ijgu7/onstFalG98xeumfzDfMBCHTwiOkHEpIIfUAZIOMlOpHr4SoFKEsed7c0yRSIop/B18z2ZNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769147720; c=relaxed/simple; bh=AshL+gXPoIG3qqr7OO2chsFUhi+3/LfRd6/uBwxw5No=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NcvYqkjtqYIRBHTokj0UJwoomokR26oCn+mvO79TVRD2A1AKJvSjR0KdbBFhpB3kin0I9WcBV6xcM4gwY1dQDjxEJtWJD7HEqjG3yNI6NHoBmCTL3JB/R5211YL8z0CehYwUl7H5NCND6Tn8FKPIGlc9mfFPDrGHZjKspJLNHUY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l+NfzNlt; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="l+NfzNlt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 957BDC19422; Fri, 23 Jan 2026 05:55:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769147718; bh=AshL+gXPoIG3qqr7OO2chsFUhi+3/LfRd6/uBwxw5No=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=l+NfzNlt2T8ZxdGSVcPAoxpI58ZVs7X6gvyD3fUk7/tKLg1GkqWn4s8tqlCmnaC5e TaMqFyfT0vfkMEhkTGessiim8eOnmjiop1iDPvmgnDGp1QzwXCNPMDFDk9dZH+rJCf Kh6V2f8HC52xPuhXPL/aPigfgpkGgM5wwjbl3Q93Afn3Bk0REORhuydinRtKxHwDMF iEBdJ3N4GM6mVSbYZqQghHuvQP+9+ipeCiEcwBSvQlaSr4BwL+Sas2jNKkT3v0vXvI MUYi/yHZMuLDLFDHjgphtT1HQW/gcauUq92nQp58oPIDO+cZeiHznwr2KcR+VSoLMu wSch+v8tNa0Xw== Message-ID: Date: Fri, 23 Jan 2026 06:55:15 +0100 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] serial: Fix not set tty->port race condition To: Krzysztof Kozlowski , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Cc: stable@vger.kernel.org References: <20260122170031.433724-2-krzysztof.kozlowski@oss.qualcomm.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 22. 01. 26, 18:00, Krzysztof Kozlowski wrote: > Revert commit bfc467db60b7 ("serial: remove redundant > tty_port_link_device()") because the tty_port_link_device() is not > redundant: the tty->port has to be confured before we call > uart_configure_port(), otherwise user-space can open console without TTY > linked to the driver. > > This tty_port_link_device() was added explicitly to avoid this exact > issue in commit fb2b90014d78 ("tty: link tty and port before configuring > it as console"), so offending commit basically reverted the fix saying > it is redundant without addressing the actual race condition presented > there. > > Reproducible always as tty->port warning on Qualcomm SoC with most of > devices disabled, so with very fast boot, and one serial device being > the console: > > printk: legacy console [ttyMSM0] enabled > printk: legacy console [ttyMSM0] enabled > printk: legacy bootconsole [qcom_geni0] disabled > printk: legacy bootconsole [qcom_geni0] disabled > ------------[ cut here ]------------ > tty_init_dev: ttyMSM driver does not set tty->port. This would crash the kernel. Fix the driver! > WARNING: drivers/tty/tty_io.c:1414 at tty_init_dev.part.0+0x228/0x25c, CPU#2: systemd/1 > Modules linked in: socinfo tcsrcc_eliza gcc_eliza sm3_ce fuse ipv6 > CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G S 6.19.0-rc4-next-20260108-00024-g2202f4d30aa8 #73 PREEMPT > Tainted: [S]=CPU_OUT_OF_SPEC > Hardware name: Qualcomm Technologies, Inc. Eliza (DT) > ... > tty_init_dev.part.0 (drivers/tty/tty_io.c:1414 (discriminator 11)) (P) > tty_open (arch/arm64/include/asm/atomic_ll_sc.h:95 (discriminator 3) drivers/tty/tty_io.c:2073 (discriminator 3) drivers/tty/tty_io.c:2120 (discriminator 3)) > chrdev_open (fs/char_dev.c:411) > do_dentry_open (fs/open.c:962) > vfs_open (fs/open.c:1094) > do_open (fs/namei.c:4634) > path_openat (fs/namei.c:4793) > do_filp_open (fs/namei.c:4820) > do_sys_openat2 (fs/open.c:1391 (discriminator 3)) > ... > Starting Network Name Resolution... > > Apparently the flow with this small Yocto-based ramdisk user-space is: > > driver (qcom_geni_serial.c): user-space: > ============================ =========== > qcom_geni_serial_probe() > uart_add_one_port() > serial_core_register_port() > serial_core_add_one_port() > uart_configure_port() > register_console() > | > | open console > | ... > | tty_init_dev() > | driver->ports[idx] is NULL > | > tty_port_register_device_attr_serdev() > tty_port_link_device() <- set driver->ports[idx] > > Fixes: bfc467db60b7 ("serial: remove redundant tty_port_link_device()") > Cc: > Signed-off-by: Krzysztof Kozlowski > --- > drivers/tty/serial/serial_core.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 0534b2eb1682..116f33f0643f 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -3077,6 +3077,7 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u > if (uport->cons && uport->dev) > of_console_check(uport->dev->of_node, uport->cons->name, uport->line); > > + tty_port_link_device(port, drv->tty_driver, uport->line); Bah, so add a comment or I (or somebody) remove it again eventually :(. thanks, -- js suse labs