From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793261401; b=AzV7FchfgHDmhB/591ygpz4iQ2amBS0jXP/dJkHKiYTmrMH8gPnCK5rXZqPhXZEZG3oh igPRvlvXSBkJIEwgkLnUeUx4WeqczV2ZgaAQsalOGCR2CEdYGaMjSK4nNP7gqg9XMH1Tt kdfnT39klXCFGySY8jREFGoBF/GHAfs5z5SyKQP++ZN0l2lWNO+28zC7zOFN7NuTLBATv EqavQa4+xKGmXxqpzZiByfSpy7GpZx0gWcedTAGkWPLcWh4yd0+dxw1xkWsi9vQcCuL1I xmxqVPSI9fcYyclDlIeeCPIPR8rKyMhydd8zGHv+AiY4/HVJKE11tgK8PuF/ecqEQSQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793261401; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=lqsKS5fffOfClnlwODzMU4wTU7v1TYqB6Y/mtnJXzQE=; b=NI6+gtLiV2r5OWy3+8L9kfvwIefw9A6OyA7J1wIytLy8p+hfxcM96Ry0Sx7RKcCieR/B RAh+iRVlm+yNRbKn/prcUiOsmF32UpXF7AkVAbAelA4frKFLD9AVRbMTXuCcsCQ3iDeVm w7UacuuQF6qSz2LrkwHe+Gtp1DYNU1lmcyq9OEwR8AsveKblPgUZaAulVfsMN0L3+UxYR LXMewpxl+9y3kYuqB588wryAg4W8wqjZ5TlywlvWVWMshRm6cLT3uk4og6vIX1t1nowVN JxcVwkYHL7L97G1h/C3faioBsJMjXT029m4PthwIYToTOxByUyN3dXpBvNxvCw9L2Cw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=vvioKGLs; 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 4FC56606A31C; Thu, 29 Oct 2026 08:10:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=vvioKGLs Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B8691F01825; Thu, 29 Oct 2026 08:10:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793261401; bh=lqsKS5fffOfClnlwODzMU4wTU7v1TYqB6Y/mtnJXzQE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=vvioKGLsoW4C0kAy2u6QKmPd89jB5ST6ddpef+dwgr5KhhwnQ6uXYS8/q0HUkFrLR lzZVVYIZatv9xXRKPegL/TLmIiH5HRYdICjkIpl6CKZUlgQk1fAtlvmSxNHDOy4OFM h4MScMAI79y8J4e9wnJayemu+GZxEWCoQ7QrVc10= Date: Thu, 29 Oct 2026 09:09:58 +0100 From: Greg KH To: Hungyu Lin Cc: jirislaby@kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tty: n_tty: convert the full VTIME interval to jiffies Message-ID: <2026102915-trailside-easiest-08fa@gregkh> References: <20261029002052.54117-1-dennylin0707@gmail.com> <2026102957-suitable-gesture-be83@gregkh> <2026102930-underwire-manmade-8083@gregkh> 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 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Oct 29, 2026 at 12:52:59AM -0700, Hungyu Lin wrote: > > Ok, and has it ever reported problems with this rounding error? This is > > very old code, changing it needs to be done only if an issue is actually > > noticed as it might be relied on, right? > > I don't have a report from users of those systems. I found this by > inspection and reproduced the early timeout using PTYs under QEMU. > > For comparison, FreeBSD's original VMIN/VTIME code keeps the timeout > in microseconds and rounds the remaining interval up when > converting to ticks: > https://github.com/freebsd/freebsd-src/commit/d32198f15b39a0f6dc29229ba4925d67d136956e > > I understand that this doesn't rule out applications depending on the > existing Linux timing. Would you consider the conversion correction > worthwhile on that basis? Unless you can prove that this is causing a problem, I would suggest leaving this as-is please. Modifying user-visable behaviour is very tricky. thanks, greg k-h