Re: [PATCH] KVM: use modern cpumask primitives, no cpumask_t on stack

[Hollis Blanchard <hollisb@us.ibm.com>]

On Mon, 2008-12-08 at 16:09 +0000, Avi Kivity wrote:
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index ba4275d..2d6ca79 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -568,14 +570,17 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
>  		if (test_and_set_bit(req, &vcpu->requests))
>  			continue;
>  		cpu = vcpu->cpu;
> -		if (cpu != -1 && cpu != me)
> -			cpu_set(cpu, cpus);
> -	}
> -	if (!cpus_empty(cpus)) {
> -		smp_call_function_mask(cpus, ack_flush, NULL, 1);
> -		called = true;
> +		if (cpus != NULL && cpu != -1 && cpu != me)
> +			cpumask_set_cpu(cpu, cpus);
>  	}
> +	if (unlikely(cpus == NULL))
> +		smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1);
> +	else if (!cpumask_empty(cpus))
> +		smp_call_function_many(cpus, ack_flush, NULL, 1);
> +	else
> +		called = false;
>  	put_cpu();
> +	free_cpumask_var(cpus);
>  	return called;
>  }

This patch breaks uniprocessor builds, because smp_call_function_many()
is only defined for CONFIG_SMP.

Avi, I think you should be able to build a PowerPC KVM kernel at this
point? That would have caught this error. Rusty, could you ack the
following:



cpumask: define smp_call_function_many() for non-SMP builds

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>

diff --git a/include/linux/smp.h b/include/linux/smp.h
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -67,13 +67,6 @@ int smp_call_function(void(*func)(void *
 /* Deprecated: use smp_call_function_many() which uses a cpumask ptr. */
 int smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info,
                                int wait);
-
-static inline void smp_call_function_many(const struct cpumask *mask,
-                                         void (*func)(void *info), void *info,
-                                         int wait)
-{
-       smp_call_function_mask(*mask, func, info, wait);
-}
 
 int smp_call_function_single(int cpuid, void (*func) (void *info), void *info,
                                int wait);
@@ -151,6 +144,13 @@ static inline void init_call_single_data
 }
 #endif /* !SMP */
 
+static inline void smp_call_function_many(const struct cpumask *mask,
+                                         void (*func)(void *info), void *info,
+                                         int wait)
+{
+       smp_call_function_mask(*mask, func, info, wait);
+}
+
 /*
  * smp_processor_id(): get the current CPU ID.
  *

-- 
Hollis Blanchard
IBM Linux Technology Center