From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756069AbbCRSOk (ORCPT ); Wed, 18 Mar 2015 14:14:40 -0400 Received: from p3plsmtps2ded03.prod.phx3.secureserver.net ([208.109.80.60]:48278 "EHLO p3plsmtps2ded03.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755541AbbCRSNH (ORCPT ); Wed, 18 Mar 2015 14:13:07 -0400 x-originating-ip: 72.167.245.219 From: "K. Y. Srinivasan" To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, vkuznets@redhat.com Cc: "K. Y. Srinivasan" Subject: [PATCH V2 10/10] Drivers: hv: vmbus: Fix a siganlling host signalling issue Date: Wed, 18 Mar 2015 12:29:30 -0700 Message-Id: <1426706970-32472-10-git-send-email-kys@microsoft.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1426706970-32472-1-git-send-email-kys@microsoft.com> References: <1426706943-32431-1-git-send-email-kys@microsoft.com> <1426706970-32472-1-git-send-email-kys@microsoft.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Handle the case when the write to the ringbuffer fails. In this case, unconditionally signal the host. Since we may have deferred signalling the host based on the kick_q parameter, signalling the host unconditionally in this case deals with the issue. Signed-off-by: K. Y. Srinivasan --- drivers/hv/channel.c | 28 ++++++++++++++++++++++++++-- 1 files changed, 26 insertions(+), 2 deletions(-) diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index fddd3b5..54da66d 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -611,7 +611,19 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer, ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal); - if ((ret == 0) && kick_q && signal) + /* + * Signalling the host is conditional on many factors: + * 1. The ring state changed from being empty to non-empty. + * This is tracked by the variable "signal". + * 2. The variable kick_q tracks if more data will be placed + * on the ring. We will not signal if more data is + * to be placed. + * + * If we cannot write to the ring-buffer; signal the host + * even if we may not have written anything. This is a rare + * enough condition that it should not matter. + */ + if (((ret == 0) && kick_q && signal) || (ret)) vmbus_setevent(channel); return ret; @@ -702,7 +714,19 @@ int vmbus_sendpacket_pagebuffer_ctl(struct vmbus_channel *channel, ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal); - if ((ret == 0) && kick_q && signal) + /* + * Signalling the host is conditional on many factors: + * 1. The ring state changed from being empty to non-empty. + * This is tracked by the variable "signal". + * 2. The variable kick_q tracks if more data will be placed + * on the ring. We will not signal if more data is + * to be placed. + * + * If we cannot write to the ring-buffer; signal the host + * even if we may not have written anything. This is a rare + * enough condition that it should not matter. + */ + if (((ret == 0) && kick_q && signal) || (ret)) vmbus_setevent(channel); return ret; -- 1.7.4.1