[PATCH 4.9 68/72] tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results
From: Greg Kroah-Hartman
Date: Wed Jul 19 2017 - 06:29:25 EST
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pavankumar Kondeti <pkondeti@xxxxxxxxxxxxxx>
commit c59f29cb144a6a0dfac16ede9dc8eafc02dc56ca upstream.
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.
Link: http://lkml.kernel.org/r/1481300417-3564-1-git-send-email-pkondeti@xxxxxxxxxxxxxx
Signed-off-by: Pavankumar Kondeti <pkondeti@xxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1906,7 +1906,7 @@ tracing_generic_entry_update(struct trac
#endif
((pc & NMI_MASK ) ? TRACE_FLAG_NMI : 0) |
((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);
}