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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 14EC0C072B1 for ; Thu, 30 May 2019 03:48:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5BA124D2F for ; Thu, 30 May 2019 03:48:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559188135; bh=D57ohe9MJE9ynAZ87YT9Yn/9+tuD5LBAyKgmV/j5pcY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=yaItBkKWfJcNVx75E3dudvkq7UPSkWmhJAjGmn+61tc6hz2leVVrj0xCs26tgfBMx qO4p7IQzk4p916NHfHnDU6HLItZ5sMz/YFZgljg/FjoQjQqmIlgZSF8VdhJo+oA0qe 57JQ6HLbFhP6tybleYwrUKOh3pQLE9QeWuKc+bWQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387573AbfE3Dsy (ORCPT ); Wed, 29 May 2019 23:48:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:58046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732143AbfE3DUR (ORCPT ); Wed, 29 May 2019 23:20:17 -0400 Received: from localhost (ip67-88-213-2.z213-88-67.customer.algx.net [67.88.213.2]) (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 31C2324913; Thu, 30 May 2019 03:20:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186417; bh=D57ohe9MJE9ynAZ87YT9Yn/9+tuD5LBAyKgmV/j5pcY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sge8uHlRmtsLZrAV7q0Y6V56U8QgS05AZyC62euBSUL83OgqcGnyDkvEyJAfqpKup 7UGkiJ3SqC5Hne28rTwNsSnlpI7m2BpEJj8ZCJ2wFvXZIKABGEBuwQcmUU5L9WeDTr k1EoG3DXxlC9LAZUJ/O1ePXxsQU5IR3arHrRp5JM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Wilson , Daniel Vetter , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Sasha Levin Subject: [PATCH 4.14 191/193] drm: Wake up next in drm_read() chain if we are forced to putback the event Date: Wed, 29 May 2019 20:07:25 -0700 Message-Id: <20190530030513.324164890@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030446.953835040@linuxfoundation.org> References: <20190530030446.953835040@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 60b801999c48b6c1dd04e653a38e2e613664264e ] After an event is sent, we try to copy it into the user buffer of the first waiter in drm_read() and if the user buffer doesn't have enough room we put it back onto the list. However, we didn't wake up any subsequent waiter, so that event may sit on the list until either a new vblank event is sent or a new waiter appears. Rare, but in the worst case may lead to a stuck process. Testcase: igt/drm_read/short-buffer-wakeup Signed-off-by: Chris Wilson Cc: Daniel Vetter Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20170804082328.17173-1-chris@chris-wilson.co.uk Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_file.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c index 03244b3c985d7..3cf07f5063ff6 100644 --- a/drivers/gpu/drm/drm_file.c +++ b/drivers/gpu/drm/drm_file.c @@ -525,6 +525,7 @@ ssize_t drm_read(struct file *filp, char __user *buffer, file_priv->event_space -= length; list_add(&e->link, &file_priv->event_list); spin_unlock_irq(&dev->event_lock); + wake_up_interruptible(&file_priv->event_wait); break; } -- 2.20.1