x86_64: Allow smp_call_function_single() to current cpu

This removes the requirement for callers to get_cpu() to check in simple
cases.

Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 8 insertions, 4 deletions

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 2ff468591625..0694940b2e73 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -357,7 +357,7 @@ __smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 }
 
 /*
- * smp_call_function_single - Run a function on another CPU
+ * smp_call_function_single - Run a function on a specific CPU
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
  * @nonatomic: Currently unused.
@@ -374,14 +374,18 @@ int smp_call_function_single (int cpu, void (*func) (void *info), void *info,
 {
         /* prevent preemption and reschedule on another processor */
         int me = get_cpu();
+
+        /* Can deadlock when called with interrupts disabled */
+        WARN_ON(irqs_disabled());
+
         if (cpu == me) {
+                local_irq_disable();
+                func(info);
+                local_irq_enable();
                 put_cpu();
                 return 0;
         }
 
-        /* Can deadlock when called with interrupts disabled */
-        WARN_ON(irqs_disabled());
-
         spin_lock_bh(&call_lock);
         __smp_call_function_single(cpu, func, info, nonatomic, wait);
         spin_unlock_bh(&call_lock);