From: Michael Kelley mikelley@microsoft.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@microsoft.com Reviewed-by: Dexuan Cui decui@microsoft.com Reviewed-by: Vitaly Kuznetsov vkuznets@redhat.com Link: https://lore.kernel.org/r/1600026449-23651-1-git-send-email-mikelley@microso... Signed-off-by: Wei Liu wei.liu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.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;