The rcutorture jitter.sh script selects a random CPU but does not check
if it is offline or online. This leads to taskset errors many times. On
my machine, hyper threading is disabled so half the cores are offline
causing taskset errors a lot of times. Let us fix this by checking from
only the online CPUs on the system.

Cc: [email protected]
Signed-off-by: Joel Fernandes (Google) <[email protected]>
---
 tools/testing/selftests/rcutorture/bin/jitter.sh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh 
b/tools/testing/selftests/rcutorture/bin/jitter.sh
index 3633828375e3..47bd9829dc55 100755
--- a/tools/testing/selftests/rcutorture/bin/jitter.sh
+++ b/tools/testing/selftests/rcutorture/bin/jitter.sh
@@ -47,10 +47,11 @@ do
                exit 0;
        fi
 
-       # Set affinity to randomly selected CPU
-       cpus=`ls /sys/devices/system/cpu/*/online |
+       # Set affinity to randomly selected online CPU
+       cpus=`grep 1 /sys/devices/system/cpu/*/online |
                sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' |
                grep -v '^0*$'`
+
        cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN {
                srand(n + me + systime());
                ncpus = split(cpus, ca);
-- 
2.21.0.392.gf8f6787159e-goog

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