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 B228E17C21C; Thu, 12 Feb 2026 08:41:13 +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=1770885673; cv=none; b=ZbFWaYHJah9HxrI66mZda4nl1TWA5Uwalsoy1myyTmNomIDeeD6eozrq2LOnDZgKamjY5tTsd0GugwXYf0fQZeofXlxpP5HEpaIW2oms5mad56R3RLsiBdRet5rAtiKOFpU3SyKY0cJyigVvIhyTTyddbPPB3JkmIQekbly2fRk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770885673; c=relaxed/simple; bh=v5a8soip+JsJkAMMNBhXJydPIRTWc9cL910WD2WRa9E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AoG3SBbdHsCKn+vzjPHhU6jwUF7pmHXpnT9KZnWrmvjPvMR1yoxAjhvZej0Ydd9dvyfhcP7deGnMEc66qB4G1i1p70y8g/Ry61r0eEsnPVSFzZY664IA+A0eimZrY1/vcE55BwI8+wmq4VGzVHGU7hW/Hi5iNhIdAW0bsFmdbtM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UKCZ9zaX; 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="UKCZ9zaX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9392C4CEF7; Thu, 12 Feb 2026 08:41:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770885673; bh=v5a8soip+JsJkAMMNBhXJydPIRTWc9cL910WD2WRa9E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=UKCZ9zaXVICCIZ0tNCgWREolaxtAZbSeCJomL3OUKyY1Ue+eMGn1iPqKSjy+rAwoP P9vFu9jtcmHw/+/LYncs31V3Dud0FEAMPuY4Es9b0j2gaXGu7/iRedjD87D01Ev7qO noBHTNKIkC8oHv0hvA96L/j/Ug0YGSJbaCwHJSOlD9Me5fRILJdDfwg5dyLa5a8XuB 7K8ahw2VGdBbXlHhG/cWBq/6CeXKzSLYG0QpzJIF1uMQuFICq21aTY/ZtNX1Cuq18t /gBPU5Ku2aINyamkI6MIB8JzcoHnNBjX0SdVaLjHD0qoWTG0OTwWEbboLMsKedaMtD LSB2fG2h6sjqg== Message-ID: <5964c41f-ddd3-406d-91b1-62fa33364163@kernel.org> Date: Thu, 12 Feb 2026 09:41:08 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] serial: 8250: always disable IRQ during THRE test To: Alban Bedel , linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Nam Cao , Andy Shevchenko , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , Greg Kroah-Hartman , Lennert Buytenhek , Peng Zhang , stable@vger.kernel.org, Muchun Song , Maximilian Lueer References: <20260209113207.2118445-1-alban.bedel@lht.dlh.de> 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 09. 02. 26, 12:32, Alban Bedel wrote: > From: Peng Zhang > > commit 039d4926379b ("serial: 8250: Toggle IER bits on only after irq > has been set up") moved IRQ setup before the THRE test, so the interrupt > handler can run during the test and race with its IIR reads. This can > produce wrong THRE test results and cause spurious registration of the > serial8250_backup_timeout timer. Unconditionally disable the IRQ for the > short duration of the test and re-enable it afterwards to avoid the race. > > Cc: stable@vger.kernel.org > Fixes: 039d4926379b ("serial: 8250: Toggle IER bits on only after irq has been set up") > Signed-off-by: Peng Zhang > Reviewed-by: Muchun Song > Signed-off-by: Alban Bedel > Tested-by: Maximilian Lueer > --- > Changelog: > > v2: Replaced disable_irq_nosync() with disable_irq() to prevent interrupts > that are currently being handled This made me to check, why/how this is possible. It appears to be, but only thanks to: 205d300aea75 serial: 8250: change lock order in serial8250_do_startup() And the change should be documented in the commit log. Especially to avoid stable backports to trees without 205d300aea75. thanks, -- js suse labs