linux-kernel - [PATCH] tracing: fix "softirq" flag detection

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Date:   Wed,  7 Dec 2016 09:08:25 +0530
From:   Pavankumar Kondeti <pkondeti@...eaurora.org>
To:     rostedt@...dmis.org, mingo@...hat.com, linux-kernel@...r.kernel.org
Cc:     pkondeti@...eaurora.org
Subject: [PATCH] tracing: fix "softirq" flag detection

The 's' flag is supposed to indicate that a softirq is running. This
can be detected by testing the preempt_count with SOFTIRQ_OFFSET.

The current code tests the preempt_count with SOFTIRQ_MASK, which
would be true even when softirqs are disabled but not serving a
softirq.

Change-Id: I084531ce806e0f7d42a38be0a7ad45977c43d158
Signed-off-by: Pavankumar Kondeti <pkondeti@...eaurora.org>
---
 kernel/trace/trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ae68222..1d0f1a1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1685,7 +1685,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
 		TRACE_FLAG_IRQS_NOSUPPORT |
 #endif
 		((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
-		((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
+		((pc & SOFTIRQ_OFFSET) ? TRACE_FLAG_SOFTIRQ : 0) |
 		(tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) |
 		(test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0);
 }
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.