[PATCH 03/11] smp: Remove get_cpu from smp_call_function_any

[Chuyi Zhou]

Now smp_call_function_single() would enable preemption before
csd_lock_wait() to reduce the critical section. To allow callers of
smp_call_function_any() to also benefit from this optimization, remove
get_cpu()/put_cpu() from smp_call_function_any().

Signed-off-by: Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx>
---
 kernel/smp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index 0858553f3666..f572716c3c7d 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -772,13 +772,18 @@ int smp_call_function_any(const struct cpumask *mask,
 	unsigned int cpu;
 	int ret;
 
+	/*
+	 * Prevent migration to another CPU after selecting the current CPU
+	 * as the target.
+	 */
+	guard(migrate)();
+
 	/* Try for same CPU (cheapest) */
-	cpu = get_cpu();
+	cpu = smp_processor_id();
 	if (!cpumask_test_cpu(cpu, mask))
 		cpu = sched_numa_find_nth_cpu(mask, 0, cpu_to_node(cpu));
 
 	ret = smp_call_function_single(cpu, func, info, wait);
-	put_cpu();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(smp_call_function_any);
-- 
2.20.1