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Drivers: hv: vmbus: Add timeout to vmbus_wait_for_unload 

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: 415719160d ("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@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Michael Kelley 2020-09-13 12:47:29 -07:00 committed by Wei Liu
parent 19873eec7e
commit 911e1987ef
1 changed files with 5 additions and 2 deletions
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7
drivers/hv/channel_mgmt.c
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@ -750,7 +750,7 @@ 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
@ -760,8 +760,11 @@ 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;