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

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 <adobriyan@gmail.com>
    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.

Fixes: c311c797998c ("cpumask: make "nr_cpumask_bits" unsigned")
Cc: <stable@vger.kernel.org> # v4.12+
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Pu Hou <bjhoupu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index c1bf75ffb8756549b1c6a5c97908ff49dd2e79aa..7e1e40323b78e1bb7a3910e1191dfbe40027b748 100644 (file)
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -823,9 +823,12 @@ static int cpumsf_pmu_event_init(struct perf_event *event)
        }
 
        /* 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.