From patchwork Fri Aug 24 02:56:27 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Vasut X-Patchwork-Id: 1369631 Return-Path: X-Original-To: patchwork-spi-devel-general@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from lists.sourceforge.net (lists.sourceforge.net [216.34.181.88]) by patchwork2.kernel.org (Postfix) with ESMTP id 37171DF2AB for ; Fri, 24 Aug 2012 02:56:37 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=sfs-ml-1.v29.ch3.sourceforge.com) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1T4k4a-0000qL-TP; Fri, 24 Aug 2012 02:56:36 +0000 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1T4k4a-0000qG-Ff for spi-devel-general@lists.sourceforge.net; Fri, 24 Aug 2012 02:56:36 +0000 X-ACL-Warn: Received: from mail-out.m-online.net ([212.18.0.9]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1T4k4Z-0004IK-JJ for spi-devel-general@lists.sourceforge.net; Fri, 24 Aug 2012 02:56:36 +0000 Received: from frontend1.mail.m-online.net (unknown [192.168.8.180]) by mail-out.m-online.net (Postfix) with ESMTP id 3X36Zj3xLCz4KK3s; Fri, 24 Aug 2012 04:56:29 +0200 (CEST) X-Auth-Info: hc0AEVLp1YAs/a0JFbpt3coFVvsN35VyPiEb/229MyM= Received: from mashiro.lan (unknown [195.140.253.167]) by smtp-auth.mnet-online.de (Postfix) with ESMTPA id 3X36Zj2Lhwzbbj3; Fri, 24 Aug 2012 04:56:29 +0200 (CEST) From: Marek Vasut To: spi-devel-general@lists.sourceforge.net Subject: [PATCH V3] mxs/spi: Fix misuse of init_completion Date: Fri, 24 Aug 2012 04:56:27 +0200 Message-Id: <1345776987-15350-1-git-send-email-marex@denx.de> X-Mailer: git-send-email 1.7.10.4 X-Spam-Score: -0.0 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.18.0.9 listed in list.dnswl.org] -0.0 AWL AWL: From: address is in the auto white-list X-Headers-End: 1T4k4Z-0004IK-JJ Cc: Marek Vasut , Fabio Estevam , Shawn Guo , Mark Brown , Chris Ball , linux-arm-kernel@lists.infradead.org X-BeenThere: spi-devel-general@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: Linux SPI core/device drivers discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: spi-devel-general-bounces@lists.sourceforge.net The init_completion() call does reinit not only the variable carrying the flag that the completion finished, but also initialized the waitqueue associated with the completion. On the contrary, the INIT_COMPLETION() call only reinits the flag. In case there was anything still stuck in the waitqueue, subsequent call to init_completion() would be able to create possible race condition. This patch uses the proper function and moves init_completion() into .probe() call of the driver, to be issued only once. Note that such scenario is impossible, since two threads can never enter the mxs_spi_txrx_dma(), since whole this section is protected by mutex in SPI core. This by no means allows this issue to exit though. Signed-off-by: Marek Vasut Cc: Chris Ball Cc: Shawn Guo Cc: Mark Brown Cc: Fabio Estevam --- drivers/spi/spi-mxs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) V2: Update the patch description and snap a whip over myself for being lazy to write one in the first place! V3: Replace INIT_WORKQUEUE() with INIT_COMPLETION(), typo in patch description. diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c index 331f600..c965cc6 100644 --- a/drivers/spi/spi-mxs.c +++ b/drivers/spi/spi-mxs.c @@ -230,7 +230,7 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs, return -EINVAL; } - init_completion(&spi->c); + INIT_COMPLETION(spi->c); if (*first) pio |= BM_SSP_CTRL0_LOCK_CS; @@ -560,6 +560,8 @@ static int __devinit mxs_spi_probe(struct platform_device *pdev) ssp->devid = devid; ssp->dma_channel = dma_channel; + init_completion(&spi->c); + ret = devm_request_irq(&pdev->dev, irq_err, mxs_ssp_irq_handler, 0, DRIVER_NAME, ssp); if (ret)