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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 9225DC677D4 for ; Mon, 8 Oct 2018 18:38:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E38B20C0A for ; Mon, 8 Oct 2018 18:38:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="yN/Pq61f" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5E38B20C0A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729110AbeJIBvK (ORCPT ); Mon, 8 Oct 2018 21:51:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:37874 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbeJIBvJ (ORCPT ); Mon, 8 Oct 2018 21:51:09 -0400 Received: from localhost (ip-213-127-77-176.ip.prioritytelecom.net [213.127.77.176]) (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 725422064A; Mon, 8 Oct 2018 18:38:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1539023886; bh=abmm+Om0PuoW2P+D6kLwKSiqIPctlh+GHnm1x5e3938=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yN/Pq61fMJfMzLJA0COXnCP5O4x6a0eGf/qMZLDWIAAt8fnLoIw7sZnsdjbJIc4NQ oZhixl42w5NiBvPn7bJg9rixd5eAUQjrHr7kegE8CRHC8WkcwIJ454sfz8NxTcNYaa AlrYM9xrV7YAld5grvA5sCTyCN6Y1DegfeywNPJs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Kuznetsov , Wei Liu , Boris Ostrovsky , Sasha Levin Subject: [PATCH 4.4 106/113] xen/manage: dont complain about an empty value in control/sysrq node Date: Mon, 8 Oct 2018 20:31:47 +0200 Message-Id: <20181008175537.161318918@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20181008175530.864641368@linuxfoundation.org> References: <20181008175530.864641368@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review 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 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vitaly Kuznetsov [ Upstream commit 87dffe86d406bee8782cac2db035acb9a28620a7 ] When guest receives a sysrq request from the host it acknowledges it by writing '\0' to control/sysrq xenstore node. This, however, make xenstore watch fire again but xenbus_scanf() fails to parse empty value with "%c" format string: sysrq: SysRq : Emergency Sync Emergency Sync complete xen:manage: Error -34 reading sysrq code in control/sysrq Ignore -ERANGE the same way we already ignore -ENOENT, empty value in control/sysrq is totally legal. Signed-off-by: Vitaly Kuznetsov Reviewed-by: Wei Liu Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/xen/manage.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -280,9 +280,11 @@ static void sysrq_handler(struct xenbus_ /* * The Xenstore watch fires directly after registering it and * after a suspend/resume cycle. So ENOENT is no error but - * might happen in those cases. + * might happen in those cases. ERANGE is observed when we get + * an empty value (''), this happens when we acknowledge the + * request by writing '\0' below. */ - if (err != -ENOENT) + if (err != -ENOENT && err != -ERANGE) pr_err("Error %d reading sysrq code in control/sysrq\n", err); xenbus_transaction_end(xbt, 1);