generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts

There is a problem that kdump(2nd kernel) sometimes hangs up due
to a pending IPI from 1st kernel. Kernel panic occurs because IPI
comes before call_single_queue is initialized.

To fix the crash, rename init_call_single_data() to call_function_init()
and call it in start_kernel() so that call_single_queue can be
initialized before enabling interrupts.

The details of the crash are:

 (1) 2nd kernel boots up

 (2) A pending IPI from 1st kernel comes when irqs are first enabled
     in start_kernel().

 (3) Kernel tries to handle the interrupt, but call_single_queue
     is not initialized yet at this point. As a result, in the
     generic_smp_call_function_single_interrupt(), NULL pointer
     dereference occurs when list_replace_init() tries to access
     &q->list.next.

Therefore this patch changes the name of init_call_single_data()
to call_function_init() and calls it before local_irq_enable()
in start_kernel().

Signed-off-by: Takao Indoh <[email protected]>
Reviewed-by: WANG Cong <[email protected]>
Acked-by: Neil Horman <[email protected]>
Acked-by: Vivek Goyal <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Milton Miller <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

init/main.c

@@ -542,6 +542,7 @@ asmlinkage void __init start_kernel(void)
 	timekeeping_init();
 	time_init();
 	profile_init();
+	call_function_init();
 	if (!irqs_disabled())
 		printk(KERN_CRIT "start_kernel(): bug: interrupts were "
 				 "enabled early\n");