From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (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 544A32D77E3; Thu, 12 Feb 2026 10:15:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770891358; cv=none; b=k+agMuZqg5kwb8hntwsEXqB66u/iuKoOdOVfACFmDzjs+iQ8ZowwBCXmdSGVjLXHCaZYAOZH+14QfC0BFdigMWGpGk7RIPbpPDoMlTd/8l3/Uz3ghzOOOW0VVnwN8aK0e59E9B81RENGYU7iFtELm9zfGF8sHRvHClO/UM1ylK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770891358; c=relaxed/simple; bh=Wk89nFUepuSXaXCGvF8acoSpbg0D5i8pnzVyOgeRsro=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=D9yiCNlZS/AAdSS0TEw02OSArMUzmI5LosN2raNfSH85cBV43POy7P/SBb87/Et8ym596tSzLyFc5AzKt8Ehbx7JxAre5Gpv9E3vd9zfBYn/IC9CftgpXESn7DE2Te/lHw8OVPXsWmtG40n4whm15/jlcZl2pgG0GL2YubyEgFc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Ji8DxQAY; arc=none smtp.client-ip=198.175.65.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Ji8DxQAY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770891357; x=1802427357; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Wk89nFUepuSXaXCGvF8acoSpbg0D5i8pnzVyOgeRsro=; b=Ji8DxQAYrjPq42bYJ9vxcYYGBk2FMGdtNDeavH+cPZGxKQFh11GptjCK sSKspGek5aFccmtRF7oIsv4vPmUHYR8GXissRTGuD1CbxS2k6QQVnNH2G pA/vCTWzjA0WBo5bCoOkA2ZVmSdRZtG2jhCnahlvG3MGJ2UWoIWwL/MYN 6orx60zXz09kGojXVISETVSMuaKJ3aGlEOCgbHHTWDHoL+wfWE6rEAuGx y67HOzQY85UGt2kJX8b8S7q/ytTiNVKplnpzgc4DwijXMZO2gWzjukFJ4 yTOXTNczzRzwIhwwXjxaY/b+Vq77AzxuAhGFYDhbESxbDGO220X7fhhTo A==; X-CSE-ConnectionGUID: DQgkvj4IRV69nGR5CAsLfA== X-CSE-MsgGUID: FUJKXL0FQwq6MESJgW9nUQ== X-IronPort-AV: E=McAfee;i="6800,10657,11698"; a="72104976" X-IronPort-AV: E=Sophos;i="6.21,286,1763452800"; d="scan'208";a="72104976" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Feb 2026 02:15:56 -0800 X-CSE-ConnectionGUID: M1pIBHV8Ttm5cMtvCOqfJg== X-CSE-MsgGUID: cEy5DnNZS4SO6lSjS0EdHg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,286,1763452800"; d="scan'208";a="212582397" Received: from egrumbac-mobl6.ger.corp.intel.com (HELO localhost) ([10.245.245.145]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Feb 2026 02:15:53 -0800 Date: Thu, 12 Feb 2026 12:15:50 +0200 From: Andy Shevchenko To: Jiri Slaby Cc: Alban Bedel , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Nam Cao , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Greg Kroah-Hartman , Lennert Buytenhek , Peng Zhang , stable@vger.kernel.org, Muchun Song , Maximilian Lueer Subject: Re: [PATCH v3] serial: 8250: always disable IRQ during THRE test Message-ID: References: <20260209113207.2118445-1-alban.bedel@lht.dlh.de> <5964c41f-ddd3-406d-91b1-62fa33364163@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5964c41f-ddd3-406d-91b1-62fa33364163@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Thu, Feb 12, 2026 at 09:41:08AM +0100, Jiri Slaby wrote: > On 09. 02. 26, 12:32, Alban Bedel wrote: > > 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. ... > > 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. There is a de facto tag Depends-on: which might be used here. -- With Best Regards, Andy Shevchenko