torture: Kill qemu, not parent process

The current hang-check machinery in the rcutorture scripts uses "$!" of
a parenthesized bash statement to capture the pid.  Unfortunately, this
captures not qemu's pid, but rather that of its parent that implements
the parenthesized statement.  This commit therefore adjusts things so as
to capture qemu's actual pid, which then allows the script to actually
kill qemu in event of a kernel hang.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 24 insertions, 6 deletions

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
index 0f80eefb0bfd..2eb8fefbe7d9 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
@@ -168,14 +168,25 @@ then
 fi
 echo "NOTE: $QEMU either did not run or was interactive" > $resdir/console.log
 echo $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append \"$qemu_append $boot_args\" > $resdir/qemu-cmd
-( $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append "$qemu_append $boot_args"; echo $? > $resdir/qemu-retval ) &
-qemu_pid=$!
+( $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append "$qemu_append $boot_args"& echo $! > $resdir/qemu_pid; wait `cat  $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) &
 commandcompleted=0
-echo Monitoring qemu job at pid $qemu_pid
+sleep 10 # Give qemu's pid a chance to reach the file
+if test -s "$resdir/qemu_pid"
+then
+        qemu_pid=`cat "$resdir/qemu_pid"`
+        echo Monitoring qemu job at pid $qemu_pid
+else
+        qemu_pid=""
+        echo Monitoring qemu job at yet-as-unknown pid
+fi
 while :
 do
+        if test -z "$qemu_pid" -a -s "$resdir/qemu_pid"
+        then
+                qemu_pid=`cat "$resdir/qemu_pid"`
+        fi
         kruntime=`awk 'BEGIN { print systime() - '"$kstarttime"' }' < /dev/null`
-        if kill -0 $qemu_pid > /dev/null 2>&1
+        if test -z "$qemu_pid" || kill -0 "$qemu_pid" > /dev/null 2>&1
         then
                 if test $kruntime -ge $seconds
                 then
@@ -195,12 +206,16 @@ do
                                 ps -fp $killpid >> $resdir/Warnings 2>&1
                         fi
                 else
-                        echo ' ---' `date`: Kernel done
+                        echo ' ---' `date`: "Kernel done"
                 fi
                 break
         fi
 done
-if test $commandcompleted -eq 0
+if test -z "$qemu_pid" -a -s "$resdir/qemu_pid"
+then
+        qemu_pid=`cat "$resdir/qemu_pid"`
+fi
+if test $commandcompleted -eq 0 -a -n "$qemu_pid"
 then
         echo Grace period for qemu job at pid $qemu_pid
         while :
@@ -220,6 +235,9 @@ then
                 fi
                 sleep 1
         done
+elif test -z "$qemu_pid"
+then
+        echo Unknown PID, cannot kill qemu command
 fi
 
 parse-torture.sh $resdir/console.log $title