From patchwork Wed Jun 7 17:45:26 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans Verkuil X-Patchwork-Id: 9772089 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 49C7360350 for ; Wed, 7 Jun 2017 17:45:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 65B72284C5 for ; Wed, 7 Jun 2017 17:45:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5A6D6284D2; Wed, 7 Jun 2017 17:45:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E3298284C5 for ; Wed, 7 Jun 2017 17:45:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 343846E289; Wed, 7 Jun 2017 17:45:31 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from lb3-smtp-cloud3.xs4all.net (lb3-smtp-cloud3.xs4all.net [194.109.24.30]) by gabe.freedesktop.org (Postfix) with ESMTPS id F05F76E289 for ; Wed, 7 Jun 2017 17:45:28 +0000 (UTC) Received: from [IPv6:2001:983:e9a7:1:ef31:4dcf:822e:7392] ([IPv6:2001:983:e9a7:1:ef31:4dcf:822e:7392]) by smtp-cloud3.xs4all.net with ESMTP id VtlS1v0083YS7uB01tlTEZ; Wed, 07 Jun 2017 19:45:27 +0200 To: Linux Media Mailing List From: Hans Verkuil Subject: [PATCH for 4.12] cec: race fix: don't return -ENONET in cec_receive() Message-ID: Date: Wed, 7 Jun 2017 19:45:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 Cc: "dri-devel@lists.freedesktop.org" X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP When calling CEC_RECEIVE do not check if the adapter is configured. Typically CEC_RECEIVE is called after a select() and if that indicates that there are messages in the receive queue, then you should always be able to dequeue a message. The race condition here is that a message has been received and is queued, so select() tells userspace that a message is available. But before the application calls CEC_RECEIVE the adapter is unconfigured (e.g. the HDMI cable is removed). Now select will always report that there is a message, but calling CEC_RECEIVE will always return -ENONET because the adapter is no longer configured and so will never actually dequeue the message. There is really no need for this check, and in fact the ENONET error code was never documented for CEC_RECEIVE. This may have been a left-over of old code that was never updated. Signed-off-by: Hans Verkuil Cc: # for v4.10 and up --- drivers/media/cec/cec-api.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/drivers/media/cec/cec-api.c b/drivers/media/cec/cec-api.c index 1359c3977101..f7eb4c54a354 100644 --- a/drivers/media/cec/cec-api.c +++ b/drivers/media/cec/cec-api.c @@ -272,16 +272,10 @@ static long cec_receive(struct cec_adapter *adap, struct cec_fh *fh, bool block, struct cec_msg __user *parg) { struct cec_msg msg = {}; - long err = 0; + long err; if (copy_from_user(&msg, parg, sizeof(msg))) return -EFAULT; - mutex_lock(&adap->lock); - if (!adap->is_configured && fh->mode_follower < CEC_MODE_MONITOR) - err = -ENONET; - mutex_unlock(&adap->lock); - if (err) - return err; err = cec_receive_msg(fh, &msg, block); if (err)