Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752021AbdHPDlB (ORCPT ); Tue, 15 Aug 2017 23:41:01 -0400 Received: from mail-sg2apc01on0117.outbound.protection.outlook.com ([104.47.125.117]:9856 "EHLO APC01-SG2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751445AbdHPDk7 (ORCPT ); Tue, 15 Aug 2017 23:40:59 -0400 From: Dexuan Cui To: "gregkh@linuxfoundation.org" , "devel@linuxdriverproject.org" CC: KY Srinivasan , Stephen Hemminger , Haiyang Zhang , "linux-kernel@vger.kernel.org" , "olaf@aepfle.de" , Vitaly Kuznetsov , "jasowang@redhat.com" , "apw@canonical.com" , Andy Lutomirski , "marcelo.cerri@canonical.com" , "leann.ogasawara@canonical.com" , "Rolf Neugebauer" , "'Marcelo Cerri'" Subject: [PATCH] vmbus: don't acquire the mutex in vmbus_hvsock_device_unregister() Thread-Topic: [PATCH] vmbus: don't acquire the mutex in vmbus_hvsock_device_unregister() Thread-Index: AdMWQV+Z8KOMY7NmS8qr+Oc1i1vT5Q== Date: Wed, 16 Aug 2017 03:40:40 +0000 Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Enabled=True; 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charset="us-ascii" MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Aug 2017 03:40:40.4569 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: KL1P15301MB0053 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v7G3f6bh009420 Content-Length: 1247 Lines: 39 Due to commit 54a66265d675 ("Drivers: hv: vmbus: Fix rescind handling"), we need this patch to resolve the below deadlock: after we get the mutex in vmbus_hvsock_device_unregister() and call vmbus_device_unregister() -> device_unregister() -> ... -> device_release() -> vmbus_device_release(), we'll get a deadlock, because vmbus_device_release() tries to get the same mutex. Signed-off-by: Dexuan Cui Cc: K. Y. Srinivasan Cc: Haiyang Zhang Cc: Stephen Hemminger --- drivers/hv/channel_mgmt.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 4bbb8de..0373611 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -922,14 +922,10 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) void vmbus_hvsock_device_unregister(struct vmbus_channel *channel) { - mutex_lock(&vmbus_connection.channel_mutex); - BUG_ON(!is_hvsock_channel(channel)); channel->rescind = true; vmbus_device_unregister(channel->device_obj); - - mutex_unlock(&vmbus_connection.channel_mutex); } EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister); -- 2.7.4