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=-8.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 AE1E1C468BC for ; Mon, 10 Jun 2019 07:56:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 875B92085A for ; Mon, 10 Jun 2019 07:56:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="ac55uDWv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388204AbfFJH4A (ORCPT ); Mon, 10 Jun 2019 03:56:00 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:42057 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387781AbfFJHz7 (ORCPT ); Mon, 10 Jun 2019 03:55:59 -0400 Received: by mail-wr1-f68.google.com with SMTP id x17so8085828wrl.9 for ; Mon, 10 Jun 2019 00:55:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=59OBAj0fI25tEYttQXITetWvFu8mb0M8xC0iXb+r1/Q=; b=ac55uDWvwtnRMO4dwo2jOwokokoGQqChSr8nLRQkch3cqmntcsHmIs5Enlxes4BMmD whsoQL32Phf74kG9p3ykb4BQpVNP5cJqt+cKlIDj4Zdm24Diem/ePySIdftWtIgPyWvy 5p0cqzqB9FFQq+TYlniqybtJAIfZ4NAgd1YaG7zkhbQvdpOCxk7J5mc279Hc2osCt1vd Yl1fUWZqlbXJ/w97BoASau/j4/JSf2CTqRYtgMXw2CLCv729XFXLUeFukUuYvVJ5gmQM G4SPTb4u2rAhJ5Y4dX5clBzE9vGyNBmO2HARalYO+9+qToitJnp5HTEtK2qpmoVHbXQM nsaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=59OBAj0fI25tEYttQXITetWvFu8mb0M8xC0iXb+r1/Q=; b=tw9Wjl4kaL4bQpuZXl7w1pytJQrgy+YRyuUgB1NEwjYcJrgJTUqI9CW7OKUjxQ2igj of6DawQ6bnyHXlY4qe+aYzjR437u+MmxcZGGQ8g/qnjErSJrhU15lJq3HYniVLYNJFJJ b7CNUK98MznYpJDTKeURCkMDLl2dS2ZH06orliG2bYLgnEKPavkWTfrEUL+6WxliBQ1n tHuRzhZWQSpwuUSJPSJfWV3XCg7jUEKOUNw3sBs+6yiBbEv0wFOHeSgktUxB1br07VOc tZtXhyRj+RVUmax9M7CqsdN4M2vjCnkbWJLwbmJV6CSn18SAknoB97UabR1qnkEDfdHo JxOg== X-Gm-Message-State: APjAAAUmPxbf+KJi1OkoqG+AMvKepRabAeP4NcK20ZDHtp4NgnsvVJ0W nnN6mFnFxMQjEhbNB7149YnJSQ== X-Google-Smtp-Source: APXvYqxbn9YaeW8aGMKMh2aP+dx2pUtvPkFwVo6Ly0icmWY5OKpn9BPA1ZwRVm/Nm5h9j9ZfLAU01g== X-Received: by 2002:adf:9ed3:: with SMTP id b19mr21441431wrf.292.1560153358334; Mon, 10 Jun 2019 00:55:58 -0700 (PDT) Received: from localhost.localdomain (233.red-79-146-84.dynamicip.rima-tde.net. [79.146.84.233]) by smtp.gmail.com with ESMTPSA id e13sm22627166wra.16.2019.06.10.00.55.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 10 Jun 2019 00:55:57 -0700 (PDT) From: Jorge Ramirez-Ortiz To: jorge.ramirez-ortiz@linaro.org, agross@kernel.org, david.brown@linaro.org, gregkh@linuxfoundation.org, jslaby@suse.com Cc: linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, khasim.mohammed@linaro.org, bjorn.andersson@linaro.org Subject: [PATCH v2] tty: serial: msm_serial: avoid system lockup condition Date: Mon, 10 Jun 2019 09:55:54 +0200 Message-Id: <20190610075554.24979-1-jorge.ramirez-ortiz@linaro.org> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The function msm_wait_for_xmitr can be taken with interrupts disabled. In order to avoid a potential system lockup - demonstrated under stress testing conditions on SoC QCS404/5 - make sure we wait for a bounded amount of time. Tested on SoC QCS404. Signed-off-by: Jorge Ramirez-Ortiz --- drivers/tty/serial/msm_serial.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 23833ad952ba..3657a24913fc 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -383,10 +383,14 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base) static inline void msm_wait_for_xmitr(struct uart_port *port) { + unsigned int timeout = 500000; + while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) { if (msm_read(port, UART_ISR) & UART_ISR_TX_READY) break; udelay(1); + if (!timeout--) + break; } msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR); } -- 2.21.0