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Patch "tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jul 19, 2017

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This is a note to let you know that I've just added the patch titled

tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tracing-use-softirq_offset-for-softirq-dectection-for-more-accurate-results.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From c59f29cb144a6a0dfac16ede9dc8eafc02dc56ca Mon Sep 17 00:00:00 2001

From: Pavankumar Kondeti <[email protected]>
Date: Fri, 9 Dec 2016 21:50:17 +0530
Subject: tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results

From: Pavankumar Kondeti <[email protected]>

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.

---
 kernel/trace/trace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/trace/trace.c +1 -1
@@ -1660,7 +1660,7 @@ tracing_generic_entry_update(struct trac
 		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);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/tracing-use-softirq_offset-for-softirq-dectection-for-more-accurate-results.patch