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Sun, 13 Sep 2020 19:48:18 +0000 From: Michael Kelley To: linux-kernel@vger.kernel.org, vkuznets@redhat.com, kys@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, linux-hyperv@vger.kernel.org Cc: mikelley@microsoft.com Subject: [PATCH 1/1] Drivers: hv: vmbus: Add timeout to vmbus_wait_for_unload Date: Sun, 13 Sep 2020 12:47:29 -0700 Message-Id: <1600026449-23651-1-git-send-email-mikelley@microsoft.com> X-Mailer: git-send-email 1.8.3.1 Content-Type: text/plain X-Originating-IP: [131.107.147.144] X-ClientProxiedBy: MWHPR21CA0031.namprd21.prod.outlook.com (2603:10b6:300:129::17) To BN6PR21MB0626.namprd21.prod.outlook.com (2603:10b6:404:11a::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mhkdev.corp.microsoft.com (131.107.147.144) by MWHPR21CA0031.namprd21.prod.outlook.com (2603:10b6:300:129::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3412.1 via Frontend Transport; Sun, 13 Sep 2020 19:48:17 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 88cd64aa-57d7-49f3-7c9f-08d8581df600 X-MS-TrafficTypeDiagnostic: BN7PR21MB1620: X-MS-Exchange-Transport-Forked: True X-LD-Processed: 72f988bf-86f1-41af-91ab-2d7cd011db47,ExtAddr X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:7691; 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But if the message isn't found for some reason, the panic path gets hung forever. Add a timeout of 10 seconds to prevent this. Fixes: 415719160de3 ("Drivers: hv: vmbus: avoid scheduling in interrupt context in vmbus_initiate_unload()") Signed-off-by: Michael Kelley --- drivers/hv/channel_mgmt.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 591106c..1d44bb6 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -731,7 +731,7 @@ static void vmbus_wait_for_unload(void) void *page_addr; struct hv_message *msg; struct vmbus_channel_message_header *hdr; - u32 message_type; + u32 message_type, i; /* * CHANNELMSG_UNLOAD_RESPONSE is always delivered to the CPU which was @@ -741,8 +741,11 @@ static void vmbus_wait_for_unload(void) * functional and vmbus_unload_response() will complete * vmbus_connection.unload_event. If not, the last thing we can do is * read message pages for all CPUs directly. + * + * Wait no more than 10 seconds so that the panic path can't get + * hung forever in case the response message isn't seen. */ - while (1) { + for (i = 0; i < 1000; i++) { if (completion_done(&vmbus_connection.unload_event)) break; -- 1.8.3.1