[PATCH rcu 04/12] torture: Make thread detection more robust by using lspcu

["Paul E. McKenney" <paulmck@kernel.org>]

From: Paul Menzel <pmenzel@molgen.mpg.de>

For consecutive numbers the lscpu command collapses the output and just
shows the range with start and end. The processors are numbered that
way on POWER8.

    $ sudo ppc64_cpu --smt=8
    $ lscpu | grep '^NUMA node'
    NUMA node(s):                    2
    NUMA node0 CPU(s):               0-79
    NUMA node8 CPU(s):               80-159

This causes the heuristic to detect the number threads per core, looking
for the number after the first comma, to fail, and QEMU aborts because of
invalid arguments.

    $ lscpu | grep '^NUMA node0' | sed -e 's/^[^,-]*(,|\-)\([0-9]*\),.*$/\1/'
    NUMA node0 CPU(s):               0-79

But the lscpu command shows the number of threads per core:

    $ sudo ppc64_cpu --smt=8
    $ lscpu | grep 'Thread(s) per core'
    Thread(s) per core:              8
    $ sudo ppc64_cpu --smt=off
    $ lscpu | grep 'Thread(s) per core'
    Thread(s) per core:              1

This commit therefore directly uses that value and replaces use of grep
with "sed -n" and its "p" command.

Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 tools/testing/selftests/rcutorture/bin/functions.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh
index c35ba24f994c..66d0414d8e4b 100644
--- a/tools/testing/selftests/rcutorture/bin/functions.sh
+++ b/tools/testing/selftests/rcutorture/bin/functions.sh
@@ -301,7 +301,7 @@ specify_qemu_cpus () {
 			echo $2 -smp $3
 			;;
 		qemu-system-ppc64)
-			nt="`lscpu | grep '^NUMA node0' | sed -e 's/^[^,]*,\([0-9]*\),.*$/\1/'`"
+			nt="`lscpu | sed -n 's/^Thread(s) per core:\s*//p'`"
 			echo $2 -smp cores=`expr \( $3 + $nt - 1 \) / $nt`,threads=$nt
 			;;
 		esac
-- 
2.31.1.189.g2e36527f23