From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3555996-1521221809-5-1000453670104523050 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1521221809; b=Tau7KH/UsF++dW2fTl3TLioT5MFVEEzG9Vb3shsigRPNYT6 TXrEThwvIpJNaf2B1R0ob7tPZarBlP1mMY/TyQMo9DvhSAm77RfWS7x4otiqeJ4z 2gFUBHT/VJnMWXF40s3wOMAWqmjkLV2HvRrQRpUhHjFXUk5/iuRZcULIeIxSGO4r o7maviiBFlH70T5HCLqwOW5PjZKJDW7QG5SWb6EB/CXZNQoRd42HSXX71DZ4iCqk xTUv9qWGAOPhmNvYesEVnUuIyWsBROymvrfSpXMWuVM6r5LfUoPXzOL2oXolQrcR thqLgigjaBNgsBeFNjv0zoXiIMNVvha4uw6ijGg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1521221809; bh=K61mrNrdzR8UBmdgxxnZ3SW5u7 WPpuQ9YHc+WviPN+A=; b=Lxvn1vxj07TcRUBBPpJg3iybIYqLvr5P3i0yl7mJUL FsKkAcfTHQuMfWZhPDVx+AABNOCyBWY2gc48EVYPNlveE5FGkiZj/w99hmqz+VA5 tBiYOc0oOJJzaMopFrWEAR2Ij5WGfri5t6htqpAMsROtj3/KVzOd3ql3kh7DHluz aUiGo9WeDNnR38PXtVgoNqpLOqaLSPw2Z4xzgrrSw2pRWjviLKM1HAwpTZBUimO8 kFJ4jtFq08sW1hBS7kPA9zyxG/0oX4G4uWRdVD9tsjw5y125j+bV//72jzzOxlI8 K06s3qaIpuDomceLC9+j4qixskfv3cxIURCoebKcoFKg== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753051AbeCPRgb (ORCPT ); Fri, 16 Mar 2018 13:36:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33942 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754053AbeCPP0m (ORCPT ); Fri, 16 Mar 2018 11:26:42 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yoshihiro Shimoda , Ulrich Hecht , Geert Uytterhoeven , Nguyen Viet Dung Subject: [PATCH 3.18 17/25] serial: sh-sci: prevent lockup on full TTY buffers Date: Fri, 16 Mar 2018 16:23:04 +0100 Message-Id: <20180316152233.456424538@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180316152232.750180431@linuxfoundation.org> References: <20180316152232.750180431@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ulrich Hecht commit 7842055bfce4bf0170d0f61df8b2add8399697be upstream. When the TTY buffers fill up to the configured maximum, a system lockup occurs: [ 598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 598.825796] 0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1 [ 598.832577] (detected by 3, t=62517 jiffies, g=296, c=295, q=126) [ 598.838755] Task dump for CPU 0: [ 598.841977] swapper/0 R running task 0 0 0 0x00000022 [ 598.849023] Call trace: [ 598.851476] __switch_to+0x98/0xb0 [ 598.854870] (null) This can be prevented by doing a dummy read of the RX data register. This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0; reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms as well. Reported-by: Yoshihiro Shimoda Signed-off-by: Ulrich Hecht Reviewed-by: Geert Uytterhoeven Cc: stable Tested-by: Nguyen Viet Dung Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sh-sci.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -736,6 +736,8 @@ static void sci_receive_chars(struct uar /* Tell the rest of the system the news. New characters! */ tty_flip_buffer_push(tport); } else { + /* TTY buffers full; read from RX reg to prevent lockup */ + serial_port_in(port, SCxRDR); serial_port_in(port, SCxSR); /* dummy read */ serial_port_out(port, SCxSR, SCxSR_RDxF_CLEAR(port)); }