Commit 2b557a06 authored by Michael Kelley's avatar Michael Kelley Committed by Greg Kroah-Hartman

Drivers: hv: vmbus: Add timeout to vmbus_wait_for_unload

[ Upstream commit 911e1987 ]

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: 41571916 ("Drivers: hv: vmbus: avoid scheduling in interrupt context in vmbus_initiate_unload()")
Signed-off-by: default avatarMichael Kelley <mikelley@microsoft.com>
Reviewed-by: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/1600026449-23651-1-git-send-email-mikelley@microsoft.comSigned-off-by: default avatarWei Liu <wei.liu@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 95ae369d
......@@ -681,7 +681,7 @@ 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
......@@ -691,8 +691,11 @@ 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;
......
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