Commit 911e1987 authored by Michael Kelley's avatar Michael Kelley Committed by Wei Liu
Browse files

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: 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.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 19873eec

drivers/hv/channel_mgmt.c

+5 −2
Original line number Diff line number Diff line
@@ -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;