[PATCH] lockdep: irqtrace subsystem, move account_system_vtime() calls into kernel/softirq.c

At the moment, powerpc and s390 have their own versions of do_softirq which
include local_bh_disable() and __local_bh_enable() calls. They end up
calling __do_softirq (in kernel/softirq.c) which also does
local_bh_disable/enable.

Apparently the two levels of disable/enable trigger a warning from some
validation code that Ingo is working on, and he would like to see the outer
level removed. But to do that, we have to move the account_system_vtime
calls that are currently in the arch do_softirq() implementations for
powerpc and s390 into the generic __do_softirq() (this is a no-op for other
archs because account_system_vtime is defined to be an empty inline
function on all other archs). This patch does that.

Signed-off-by: Paul Mackerras <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/powerpc/kernel/irq.c

···
 
 	local_irq_save(flags);
 
-	if (local_softirq_pending()) {
-		account_system_vtime(current);
-		local_bh_disable();
+	if (local_softirq_pending())
 		do_softirq_onstack();
-		account_system_vtime(current);
-		_local_bh_enable();
-	}
 
 	local_irq_restore(flags);
 }

arch/s390/kernel/irq.c

···
 
 	local_irq_save(flags);
 
-	account_system_vtime(current);
-
-	local_bh_disable();
-
 	if (local_softirq_pending()) {
 		/* Get current stack pointer. */
 		asm volatile("la %0,0(15)" : "=a" (old));
···
 			/* We are already on the async stack. */
 			__do_softirq();
 	}
-
-	account_system_vtime(current);
-
-	_local_bh_enable();
 
 	local_irq_restore(flags);
 }

kernel/softirq.c

···
 	int cpu;
 
 	pending = local_softirq_pending();
+	account_system_vtime(current);
+
 	__local_bh_disable((unsigned long)__builtin_return_address(0));
 	trace_softirq_enter();
 
···
 		wakeup_softirqd();
 
 	trace_softirq_exit();
+
+	account_system_vtime(current);
 	_local_bh_enable();
 }