perf: Fix get_recursion_context()

One should use in_serving_softirq() to detect SoftIRQ context.

Fixes: 96f6d444 ("perf_counter: avoid recursion")
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201030151955.120572175@infradead.org

kernel/events/internal.h

@@ -211,7 +211,7 @@ static inline int get_recursion_context(int *recursion)
 		rctx = 3;
 	else if (in_irq())
 		rctx = 2;
-	else if (in_softirq())
+	else if (in_serving_softirq())
 		rctx = 1;
 	else
 		rctx = 0;