[PATCH 4/6] perf: Optimize get_recursion_context()

[Peter Zijlstra]

  "Look ma, no branches!"

Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 kernel/events/internal.h |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -205,16 +205,15 @@ DEFINE_OUTPUT_COPY(__output_copy_user, a
 
 static inline int get_recursion_context(int *recursion)
 {
-	int rctx;
+	unsigned int pc = preempt_count();
+	unsigned int rctx = 0;
 
-	if (unlikely(in_nmi()))
-		rctx = 3;
-	else if (in_irq())
-		rctx = 2;
-	else if (in_serving_softirq())
-		rctx = 1;
-	else
-		rctx = 0;
+	if (pc & (NMI_MASK))
+		rctx++;
+	if (pc & (NMI_MASK | HARDIRQ_MASK))
+		rctx++;
+	if (pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET))
+		rctx++;
 
 	if (recursion[rctx])
 		return -1;