[PATCH] kvm: avoid unused variable warning for UP builds

From: Paolo Bonzini
Date: Wed Jul 05 2017 - 06:35:47 EST


The uniprocessor version of smp_call_function_many does not evaluate
all of its argument, and the compiler emits a warning about "wait"
being unused. This breaks the build on architectures for which
"-Werror" is enabled by default.

Work around it by moving the invocation of smp_call_function_many to
its own inline function.

Reported-by: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 7a97cec26b94c909f4cbad2dc3186af3e457a522
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f0fe9d02f6bb..09368501d9cf 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -187,12 +187,23 @@ static void ack_flush(void *_completed)
{
}

+static inline bool kvm_kick_many_cpus(const struct cpumask *cpus, bool wait)
+{
+ if (unlikely(!cpus))
+ cpus = cpu_online_mask;
+
+ if (cpumask_empty(cpus))
+ return false;
+
+ smp_call_function_many(cpus, ack_flush, NULL, wait);
+ return true;
+}
+
bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
{
int i, cpu, me;
cpumask_var_t cpus;
- bool called = true;
- bool wait = req & KVM_REQUEST_WAIT;
+ bool called;
struct kvm_vcpu *vcpu;

zalloc_cpumask_var(&cpus, GFP_ATOMIC);
@@ -207,14 +218,9 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)

if (cpus != NULL && cpu != -1 && cpu != me &&
kvm_request_needs_ipi(vcpu, req))
- cpumask_set_cpu(cpu, cpus);
+ __cpumask_set_cpu(cpu, cpus);
}
- if (unlikely(cpus == NULL))
- smp_call_function_many(cpu_online_mask, ack_flush, NULL, wait);
- else if (!cpumask_empty(cpus))
- smp_call_function_many(cpus, ack_flush, NULL, wait);
- else
- called = false;
+ called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
put_cpu();
free_cpumask_var(cpus);
return called;
--
1.8.3.1