From patchwork Tue Apr 12 10:43:14 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Liu X-Patchwork-Id: 609335 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3qkk5m05cwz9t43 for ; Tue, 12 Apr 2016 20:42:20 +1000 (AEST) Received: from localhost ([::1]:46674 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apvlx-0002ED-TJ for incoming@patchwork.ozlabs.org; Tue, 12 Apr 2016 06:42:17 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60605) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apvla-0001NM-So for qemu-devel@nongnu.org; Tue, 12 Apr 2016 06:41:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1apvlW-000748-Fb for qemu-devel@nongnu.org; Tue, 12 Apr 2016 06:41:54 -0400 Received: from smtp.citrix.com ([66.165.176.89]:59446) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apvlW-000737-Ax for qemu-devel@nongnu.org; Tue, 12 Apr 2016 06:41:50 -0400 X-IronPort-AV: E=Sophos;i="5.24,473,1454976000"; d="scan'208";a="346423938" From: Wei Liu To: Date: Tue, 12 Apr 2016 11:43:14 +0100 Message-ID: <1460457796-1779-2-git-send-email-wei.liu2@citrix.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1460457796-1779-1-git-send-email-wei.liu2@citrix.com> References: <1460457796-1779-1-git-send-email-wei.liu2@citrix.com> MIME-Version: 1.0 X-DLP: MIA1 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 66.165.176.89 Subject: [Qemu-devel] [PATCH v2 1/3] xenfb: use the correct condition to avoid excessive looping X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony Perard , Xen-devel , Stefano Stabellini , Wei Liu Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" In commit ac0487e1 ("xenfb.c: avoid expensive loops when prod <= out_cons"), ">=" was used. In fact, a full ring is a legit state. Correct the test to use ">". Reported-by: "Hao, Xudong" Signed-off-by: Wei Liu Tested-by: "Hao, Xudong" Acked-by: Anthony Perard Acked-by: Stefano Stabellini --- Cc: Stefano Stabellini Cc: Anthony Perard Backport candidate to our own tree. --- hw/display/xenfb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c index 40b096a..9866dfd 100644 --- a/hw/display/xenfb.c +++ b/hw/display/xenfb.c @@ -775,7 +775,7 @@ static void xenfb_handle_events(struct XenFB *xenfb) prod = page->out_prod; out_cons = page->out_cons; - if (prod - out_cons >= XENFB_OUT_RING_LEN) { + if (prod - out_cons > XENFB_OUT_RING_LEN) { return; } xen_rmb(); /* ensure we see ring contents up to prod */