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Commit 8fd7675c authored by Satyam Sharma's avatar Satyam Sharma Committed by Paul Mackerras
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[POWERPC] Avoid pointless WARN_ON(irqs_disabled()) from panic codepath 



> ------------[ cut here ]------------
> Badness at arch/powerpc/kernel/smp.c:202

comes when smp_call_function_map() has been called with irqs disabled,
which is illegal. However, there is a special case, the panic() codepath,
when we do not want to warn about this -- warning at that time is pointless
anyway, and only serves to scroll away the *real* cause of the panic and
distracts from the real bug.

* So let's extract the WARN_ON() from smp_call_function_map() into all its
  callers -- smp_call_function() and smp_call_function_single()

* Also, introduce another caller of smp_call_function_map(), namely
  __smp_call_function() (and make smp_call_function() a wrapper over this)
  which does *not* warn about disabled irqs

* Use this __smp_call_function() from the panic codepath's smp_send_stop()

We also end having to move code of smp_send_stop() below the definition
of __smp_call_function().

Signed-off-by: default avatarSatyam Sharma <satyam@infradead.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 17b5ee04

arch/powerpc/kernel/smp.c

+18 −9
Original line number Diff line number Diff line
@@ -152,11 +152,6 @@ static void stop_this_cpu(void *dummy) 
		;

}



void smp_send_stop(void)

{

	smp_call_function(stop_this_cpu, NULL, 1, 0);

}



/*

 * Structure and data for smp_call_function(). This is designed to minimise

 * static memory requirements. It also looks cleaner.
@@ -198,9 +193,6 @@ int smp_call_function_map(void (*func) (void *info), void *info, int nonatomic, 
	int cpu;

	u64 timeout;



	/* Can deadlock when called with interrupts disabled */

	WARN_ON(irqs_disabled());



	if (unlikely(smp_ops == NULL))

		return ret;
@@ -270,10 +262,19 @@ int smp_call_function_map(void (*func) (void *info), void *info, int nonatomic, 
	return ret;

}



static int __smp_call_function(void (*func)(void *info), void *info,

			       int nonatomic, int wait)

{

	return smp_call_function_map(func,info,nonatomic,wait,cpu_online_map);

}



int smp_call_function(void (*func) (void *info), void *info, int nonatomic,

			int wait)

{

	return smp_call_function_map(func,info,nonatomic,wait,cpu_online_map);

	/* Can deadlock when called with interrupts disabled */

	WARN_ON(irqs_disabled());



	return __smp_call_function(func, info, nonatomic, wait);

}

EXPORT_SYMBOL(smp_call_function);
@@ -283,6 +284,9 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int 
	cpumask_t map = CPU_MASK_NONE;

	int ret = 0;



	/* Can deadlock when called with interrupts disabled */

	WARN_ON(irqs_disabled());



	if (!cpu_online(cpu))

		return -EINVAL;
@@ -299,6 +303,11 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int 
}

EXPORT_SYMBOL(smp_call_function_single);



void smp_send_stop(void)

{

	__smp_call_function(stop_this_cpu, NULL, 1, 0);

}



void smp_call_function_interrupt(void)

{

	void (*func) (void *info);