From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 859DBC4360F for ; Thu, 4 Apr 2019 08:58:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 497E021738 for ; Thu, 4 Apr 2019 08:58:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554368306; bh=0inoD4sMunmJFLcNmu9pHM6tNu4FBjqx16HI2ibw1Eg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Md4cBv6kly42nxG96YEqYLwNHrsAaNbrlwI6vbeTb23jVKpBBevTMdTPWms+LH6QC 41pnU/nAJOSe2fTyXQP+nAUO1JiYxn8DlVF4bFQOzsD5UwuEGgjcWsQd2paiGWCmDG p8Cf4sBQTq2vy4Pk53hNexfjSBoG41HI7btvt35I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730851AbfDDI6Y (ORCPT ); Thu, 4 Apr 2019 04:58:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:34288 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730228AbfDDI6X (ORCPT ); Thu, 4 Apr 2019 04:58:23 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 04C31217D9; Thu, 4 Apr 2019 08:58:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554368302; bh=0inoD4sMunmJFLcNmu9pHM6tNu4FBjqx16HI2ibw1Eg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yPhmO/+AVm0uwedBgwNHBuIRKBpfvCy3h+ef/3Wecj0oZw5ukvaHL/T1K3VPDBY+E ITbgaw1smyi1esO/nXKJvVQYWJP24u3bgsbYedWtExr4Ofvs2gF+VYrRqWqJhM69gt 9iVRORUEBmqKbp1iv00Tpiyr3VCJzGDNvMZzZyOI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Manfred Schlaegl , Martin Kepplinger , Sasha Levin Subject: [PATCH 4.14 097/121] tty: increase the default flip buffer limit to 2*640K Date: Thu, 4 Apr 2019 10:48:05 +0200 Message-Id: <20190404084550.580608669@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084545.245659903@linuxfoundation.org> References: <20190404084545.245659903@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 7ab57b76ebf632bf2231ccabe26bea33868118c6 ] We increase the default limit for buffer memory allocation by a factor of 10 to 640K to prevent data loss when using fast serial interfaces. For example when using RS485 without flow-control at speeds of 1Mbit/s an upwards we've run into problems such as applications being too slow to read out this buffer (on embedded devices based on imx53 or imx6). If you want to write transmitted data to a slow SD card and thus have realtime requirements, this limit can become a problem. That shouldn't be the case and 640K buffers fix such problems for us. This value is a maximum limit for allocation only. It has no effect on systems that currently run fine. When transmission is slow enough applications and hardware can keep up and increasing this limit doesn't change anything. It only _allows_ to allocate more than 2*64K in cases we currently fail to allocate memory despite having some. Signed-off-by: Manfred Schlaegl Signed-off-by: Martin Kepplinger Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/tty_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 217114227f8d..cf11882d2602 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -25,7 +25,7 @@ * Byte threshold to limit memory consumption for flip buffers. * The actual memory limit is > 2x this amount. */ -#define TTYB_DEFAULT_MEM_LIMIT 65536 +#define TTYB_DEFAULT_MEM_LIMIT (640 * 1024UL) /* * We default to dicing tty buffer allocations to this many characters -- 2.19.1