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authorRichard Purdie <richard.purdie@linuxfoundation.org>2013-03-20 22:58:30 +0000
committerRichard Purdie <richard.purdie@linuxfoundation.org>2013-03-20 23:09:21 +0000
commit98471be6e58451016200cfd10e64e8ae6266c801 (patch)
tree9e6ffb4b097f596323696050d2d73b8b110fe270
parent67f1083a10f7435aeb861ba2e872d6498375d927 (diff)
downloadopenembedded-core-contrib-98471be6e58451016200cfd10e64e8ae6266c801.tar.gz
scripts/runqemu-internal: Fix lock races
There are two problems here. Firstly the grep command is unanchored so pid 345 will match against 12345 and so on. The second issue is that there are several context switched between attempting the lock and then writing the pid to it. Between the two issues, there were issues appearing on the autobuilder due to these conflicts. This patch replaces the mechanism with flock on fd 8 which should be a safer mechanism to use. Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
-rwxr-xr-xscripts/runqemu-internal19
1 files changed, 7 insertions, 12 deletions
diff --git a/scripts/runqemu-internal b/scripts/runqemu-internal
index e53e40c783f..f06870e9725 100755
--- a/scripts/runqemu-internal
+++ b/scripts/runqemu-internal
@@ -112,18 +112,12 @@ acquire_lock() {
return 1
fi
- if [ -e "$lockfile.lock" ]; then
- # Check that the lockfile is not stale
- ps=`ps -eo pid | grep $(cat $lockfile.lock)`
- if [ -z "$ps" ]; then
- echo "WARNING: Stale lock file detected, deleting $lockfile.lock."
- rm -f $lockfile.lock
- echo $$ > $lockfile.lock
- else
- return 1
- fi
- else
- echo $$ > $lockfile.lock
+ touch $lockfile.lock
+ exec 8>$lockfile.lock
+ flock -n -x 8
+ if [ $? -ne 0 ]; then
+ exec 8>&-
+ return 1
fi
return 0
@@ -137,6 +131,7 @@ release_lock() {
fi
rm -f $lockfile.lock
+ exec 8>&-
}
LOCKDIR="/tmp/qemu-tap-locks"