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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 58772C43381 for ; Wed, 27 Mar 2019 18:24:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20EA220651 for ; Wed, 27 Mar 2019 18:24:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553711099; bh=sHtdLTQRkeQ9um9EJ1hPweg7WP4EVab1NCtM0MxKndk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eQSUCQyYpcKDw1Cddrxj+OgyhwjgLH4q9s2aEWdf5u+q9VVsaKl9WpU2hhx3Y4E67 HHprToKhtjSlKspdKHCiVU//2C8mu33st4K+f2LX41IZsnLYVfkvtNDSqkwOxVYtuw 1LpYa32vVxWbx+0UwcvGux1THCFgPl/oN13K5K64= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391617AbfC0SY5 (ORCPT ); Wed, 27 Mar 2019 14:24:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:43924 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391607AbfC0SYz (ORCPT ); Wed, 27 Mar 2019 14:24:55 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8E9ED206BA; Wed, 27 Mar 2019 18:24:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553711094; bh=sHtdLTQRkeQ9um9EJ1hPweg7WP4EVab1NCtM0MxKndk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gxJuE7d5bzGk4X8ZuAuxnrtFVOtsgMfNDr6Bo3tBwY2gr1Pt54BVkqKG2Ur4ZJJYc wrB0Gj0PIQ/F/P/gNHG3ipEGSBtHLTb1AUD7YXRPGFs0nE0iYeN/I1K0WHfjHEwwJ/ Dw/6Xjy6HfoUMvZU/NKK/poun0BEDHxrnmy9ttjg= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Manfred Schlaegl , Martin Kepplinger , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 4.4 50/63] tty: increase the default flip buffer limit to 2*640K Date: Wed, 27 Mar 2019 14:23:10 -0400 Message-Id: <20190327182323.18577-50-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327182323.18577-1-sashal@kernel.org> References: <20190327182323.18577-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Manfred Schlaegl [ 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 355e9cad680d..4706df20191b 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