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,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 AB477C28CC0 for ; Thu, 30 May 2019 03:25:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 815E324A65 for ; Thu, 30 May 2019 03:25:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186727; bh=0Yf7YGQ/sEpb1kMylafb/6YPgn3HoZ7N3cN3eq1HrTs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WdoHcMXlUp6FSjJ3QMDEePLRJyeSmVSrTyF/09W/HkFemvBUXxFpiwS8cV7Pfhaaz ABBG+dAFlqs2TUEfEWCT3mWDjBnW8Q6VvMPRMas6OqUqHMbg1L1bh/CjbT/3MNTFnz zv8pK7l5XFZX6E1ydEAd5MseY4X77FobwGuBumes= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732868AbfE3DZ0 (ORCPT ); Wed, 29 May 2019 23:25:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:51336 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731549AbfE3DS2 (ORCPT ); Wed, 29 May 2019 23:18:28 -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 42419247C9; Thu, 30 May 2019 03:18:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186307; bh=0Yf7YGQ/sEpb1kMylafb/6YPgn3HoZ7N3cN3eq1HrTs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hCogC67faGCcET/7J7GXCV7w3Em/aNIANPz9LUCqtK3s1MA6DuSvcQCUri5B7aSW7 wmubR0gxjag0sdFSRNPQbx3fjX3JEh63SE3CXtCrsjDKn6JY3YtpWI9vE6qjarT+ND Zbh7uOwCtzoG7hLg4/iheBFyNG5MBGiYJgCW6lig= 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 4.19 272/276] drm: Wake up next in drm_read() chain if we are forced to putback the event Date: Wed, 29 May 2019 20:07:10 -0700 Message-Id: <20190530030542.215922846@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030523.133519668@linuxfoundation.org> References: <20190530030523.133519668@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 e4ccb52c67ea4..334addaca9c54 100644 --- a/drivers/gpu/drm/drm_file.c +++ b/drivers/gpu/drm/drm_file.c @@ -567,6 +567,7 @@ 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