From: Tejun Heo <tj@kernel.org>
Date: Mon, 13 Apr 2020 12:27:57 -0400
Subject: [PATCH] iocost_monitor: exit successfully if interval is zero
References: bsc#1175995,jsc#SLE-15608
Git-commit: f4fe3ea636385a51f1dfbb27c387a04b12b919e9
Patch-mainline: v5.8-rc1

This is to help external tools to decide whether iocost_monitor has all its
requirements met or not based on the exit status of an -i0 run.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 tools/cgroup/iocost_monitor.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/cgroup/iocost_monitor.py b/tools/cgroup/iocost_monitor.py
index 7427a5ee761b..eb2363b868c5 100644
--- a/tools/cgroup/iocost_monitor.py
+++ b/tools/cgroup/iocost_monitor.py
@@ -28,7 +28,8 @@ parser.add_argument('devname', metavar='DEV',
 parser.add_argument('--cgroup', action='append', metavar='REGEX',
                     help='Regex for target cgroups, ')
 parser.add_argument('--interval', '-i', metavar='SECONDS', type=float, default=1,
-                    help='Monitoring interval in seconds')
+                    help='Monitoring interval in seconds (0 exits immediately '
+                    'after checking requirements)')
 parser.add_argument('--json', action='store_true',
                     help='Output in json')
 args = parser.parse_args()
@@ -243,6 +244,9 @@ for i, ptr in radix_tree_for_each(blkcg_root.blkg_tree.address_of_()):
 if ioc is None:
     err(f'Could not find ioc for {devname}');
 
+if interval == 0:
+    sys.exit(0)
+
 # Keep printing
 while True:
     now = time.time()
-- 
2.16.4