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Date: Mon, 21 Sep 2020 18:28:13 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Michael Kelley <mikelley@...rosoft.com>, Dexuan Cui <decui@...rosoft.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Wei Liu <wei.liu@...nel.org>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 4.19 29/49] Drivers: hv: vmbus: Add timeout to vmbus_wait_for_unload From: Michael Kelley <mikelley@...rosoft.com> [ Upstream commit 911e1987efc8f3e6445955fbae7f54b428b92bd3 ] vmbus_wait_for_unload() looks for a CHANNELMSG_UNLOAD_RESPONSE message coming from Hyper-V. 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 <mikelley@...rosoft.com> Reviewed-by: Dexuan Cui <decui@...rosoft.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com> Link: https://lore.kernel.org/r/1600026449-23651-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@...nel.org> Signed-off-by: Sasha Levin <sashal@...nel.org> --- 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 c83361a8e2033..7920b0d7e35a7 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -779,7 +779,7 @@ 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 @@ -789,8 +789,11 @@ 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; -- 2.25.1
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