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=unavailable 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 B9C6AC10F11 for ; Wed, 24 Apr 2019 17:13:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EA99218FE for ; Wed, 24 Apr 2019 17:13:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556126007; bh=SfZAlUxGsb7L9dYWfDuiC52WgNrtkFNKkEGOWhDguJE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0C98bASYpyr2Zh9c7kKjbwJJV+wmyOAgBMEl8p9qQzyBeLvIzBSil0I3HZT4D1acs TgkJd5OzN9n2V6wPdrlkVNukQeOPlxyM2A+sD8Tg49COv9o+rTa8k4fNM5s0f/N385 il7CYkAa0xvvr8j9TioEeaRfh7IEGLxAF40O1CjY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387878AbfDXRN0 (ORCPT ); Wed, 24 Apr 2019 13:13:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:37444 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387853AbfDXRNY (ORCPT ); Wed, 24 Apr 2019 13:13:24 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (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 0134E21903; Wed, 24 Apr 2019 17:13:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556126003; bh=SfZAlUxGsb7L9dYWfDuiC52WgNrtkFNKkEGOWhDguJE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LPrDifWNUu0Zq0ue4WYEJGFT4b0KFi3NEwMxyWazKFYKSulRGXxsS8N7eoKF1jL3f la7zysvBZgl6mjTdCksVcEL0Tmoyiv4bWKVhUG7hqfDzDnj2EFQJxIoysfYsNQC9BD /LmLMCNNlHIroXQ2pkL8SB1IaoY+nQocpKujZbFY= 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 3.18 032/104] tty: increase the default flip buffer limit to 2*640K Date: Wed, 24 Apr 2019 19:08:49 +0200 Message-Id: <20190424170857.532188481@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190424170839.996641496@linuxfoundation.org> References: <20190424170839.996641496@linuxfoundation.org> User-Agent: quilt/0.66 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 [ 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 0d3fc2dae23a..50616c949e8e 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