From 9deb8c7dfd9b119884543416e4c681cbe21d97b2 Mon Sep 17 00:00:00 2001
From: Karel Zak
Date: Wed, 6 Dec 2017 14:21:38 +0100
Subject: tests: add lock on shared resources (e.g. scsi_debug)

The patch enables flock for scsi_debug to avoid collision between
tests. The patch also adds ./run.sh --nolocks to disable this feature.

Signed-off-by: Karel Zak <kzak@redhat.com>
---
 tests/functions.sh | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'tests/functions.sh')

diff --git a/tests/functions.sh b/tests/functions.sh
index 5b9b61c05..0409b6283 100644
--- a/tests/functions.sh
+++ b/tests/functions.sh
@@ -271,6 +271,9 @@ function ts_init_env {
 	TS_OUTDIR="$top_builddir/tests/output/$TS_COMPONENT"
 	TS_DIFFDIR="$top_builddir/tests/diff/$TS_COMPONENT"
 
+	TS_NOLOCKS=$(ts_has_option "nolocks" "$*")
+	TS_LOCKDIR="$top_builddir/tests/output"
+
 	ts_init_core_env
 
 	TS_VERBOSE=$(ts_has_option "verbose" "$*")
@@ -673,11 +676,34 @@ function ts_fdisk_clean {
 		$TS_OUTPUT
 }
 
+
+function ts_lock {
+	local resource="$1"
+	local lockfile="${TS_LOCKDIR}/${resource}.lock"
+
+	if [ "$TS_NOLOCKS" == "yes" ]; then
+		return 0
+	fi
+
+	# Don't lock if flock(1) is missing
+	type "flock" >/dev/null 2>&1 || return 1
+
+	eval "exec 200>$lockfile"
+	flock --exclusive --timeout 30 200 || ts_skip "failed to lock $resource"
+}
+
+# Note that flock(2) lock is released on FD close.
+function ts_unlock {
+	200<&-
+}
+
 function ts_scsi_debug_init {
 	local devname
 	local t
 	TS_DEVICE="none"
 
+	ts_lock "scsi_debug"
+
 	# dry run is not really reliable, real modprobe may still fail
 	modprobe --dry-run --quiet scsi_debug &>/dev/null \
 		|| ts_skip "missing scsi_debug module (dry-run)"
@@ -746,6 +772,7 @@ function ts_scsi_debug_rmmod {
 
 	# TODO unset TS_DEVICE, check that nobody uses it later, e.g. ts_fdisk_clean
 
+	ts_unlock "scsi_debug"
 	return 0
 }
 
-- 
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