Patch "s390/perf: fix bug when creating per-thread event" has been added to the 4.13-stable tree

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

s390/perf: fix bug when creating per-thread event

to the 4.13-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:
s390-perf-fix-bug-when-creating-per-thread-event.patch
and it can be found in the queue-4.13 subdirectory.

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

From: Pu Hou <[email protected]>
Date: Tue, 5 Sep 2017 05:17:24 +0200
Subject: s390/perf: fix bug when creating per-thread event

From: Pu Hou <[email protected]>

commit fc3100d64f0ae383ae8d845989103da06d62763b upstream.

A per-thread event could not be created correctly like below:

perf record --per-thread -e rB0000 -- sleep 1
Error:
The sys_perf_event_open() syscall returned with 19 (No such device) for event (rB0000). /bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?

This bug was introduced by:

commit c311c797998c1e70eade463dd60b843da4f1a203
Author: Alexey Dobriyan <[email protected]>
Date: Mon May 8 15:56:15 2017 -0700

cpumask: make "nr_cpumask_bits" unsigned

If a per-thread event is not attached to any CPU, the cpu field in struct perf_event is -1. The above commit converts the CPU number to unsigned int, which result in an illegal CPU number.

---
 arch/s390/kernel/perf_cpum_sf.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

@@ -823,9 +823,12 @@ static int cpumsf_pmu_event_init(struct
 	}
 
 	/* Check online status of the CPU to which the event is pinned */
-	if ((unsigned int)event->cpu >= nr_cpumask_bits ||
-	    (event->cpu >= 0 && !cpu_online(event->cpu)))
-		return -ENODEV;
+	if (event->cpu >= 0) {
+		if ((unsigned int)event->cpu >= nr_cpumask_bits)
+			return -ENODEV;
+		if (!cpu_online(event->cpu))
+			return -ENODEV;
+	}
 
 	/* Force reset of idle/hv excludes regardless of what the
 	 * user requested.

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

queue-4.13/s390-perf-fix-bug-when-creating-per-thread-event.patch