Drivers: hv: vmbus: add special crash handler
Full kernel hang is observed when kdump kernel starts after a crash. This
hang happens in vmbus_negotiate_version() function on
wait_for_completion() as Hyper-V host (Win2012R2 in my testing) never
responds to CHANNELMSG_INITIATE_CONTACT as it thinks the connection is
already established. We need to perform some mandatory minimalistic
cleanup before we start new kernel.
Reported-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 31748a2..1ed9b32 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1071,6 +1071,18 @@
hv_cleanup();
};
+static void hv_crash_handler(struct pt_regs *regs)
+{
+ vmbus_initiate_unload();
+ /*
+ * In crash handler we can't schedule synic cleanup for all CPUs,
+ * doing the cleanup for current CPU only. This should be sufficient
+ * for kdump.
+ */
+ hv_synic_cleanup(NULL);
+ hv_cleanup();
+};
+
static int __init hv_acpi_init(void)
{
int ret, t;
@@ -1104,6 +1116,7 @@
goto cleanup;
hv_setup_kexec_handler(hv_kexec_handler);
+ hv_setup_crash_handler(hv_crash_handler);
return 0;
@@ -1118,6 +1131,7 @@
int cpu;
hv_remove_kexec_handler();
+ hv_remove_crash_handler();
vmbus_connection.conn_state = DISCONNECTED;
hv_synic_clockevents_cleanup();
vmbus_disconnect();