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 07DF62EA48F; Fri, 23 Jan 2026 07:35:21 +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=1769153722; cv=none; b=PjospcIG/KHwyy+WgXu8gagdlS3oTE3N/9GutL373zaMkj4fVA+FfjMZEt2rHrTnRgr7SZe6ZF5gWFOgDEfnk38Aq1NbU3I+xklJ281uDz11JV1vrNWC3H4s4R2yxlsxR4RgDFBxhdxUpx3jA/RM971KNVWMNHpdt//DDm9+g7Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769153722; c=relaxed/simple; bh=GKOeyS1K3rfOAmVVi3P0BY1kZ4FOXbUQ5mLzkw9Qnhk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=dixQsRn86yyomBJ8GCmNL92kdY5JAsGBnBzvollRonmlx9p/aE3M2j5iEoMBqQrVgFYGT8//pLXKWikHfK10I5HS2SG3J9r/E3VaHHoEvIlfGQRXtnuySwmTQnS/aESrpE564aDJ/8gVZe7G7CnlHLVPASAn3wUZ4jjVJBJ8fsU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cdnFHa6a; 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="cdnFHa6a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 913A9C4CEF1; Fri, 23 Jan 2026 07:35:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769153721; bh=GKOeyS1K3rfOAmVVi3P0BY1kZ4FOXbUQ5mLzkw9Qnhk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cdnFHa6acOhen3sG8YsgihUo67aSjrJ11MNnbM4wzKfrCG+DvmnzzDj8XAXm9u0/x o+ODFNva8MQpI61LQnbSq2C1fqAb0mx8DG7TUIr51+aO2ohjrUz6ocKnPNMaEGKiSA y7tgcbAchwN/odopNH1/ImC948GoArXGwnrD9NNnOjqKEqio//Hd9BU3jFTCzb8U3j cso9KRc4X/uYBEqmf4lTSysxgoRgJJCwGYBRM1SLhJhhpv3MoZ/1rikCpQHq6XxHld ZDqMqgseZExfl4fRdajbneQHBLSLXW7w7XfW96yMhrZXeyu17xJBk6jo89kxMOkkDt Agh1MH4qECfiA== Message-ID: <9a5867b0-a271-43b9-9b02-743185ee83c2@kernel.org> Date: Fri, 23 Jan 2026 08:35:18 +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 v2] 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: <20260123072139.53293-2-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 23. 01. 26, 8:21, 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 Thanks for the update. Reviewed-by: Jiri Slaby -- js suse labs