From: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Date: Tue, 19 Jul 2022 02:52:16 +0000 (+0900)
Subject: common/cpuhotplug: allow _offline_cpu() call in sub-shell
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=107256dc53d55f558e349e463a5a99c3bb6b4189;p=users%2Fhch%2Fblktests.git

common/cpuhotplug: allow _offline_cpu() call in sub-shell

The helper function _offline_cpu() sets a value to RESTORE_CPUS_ONLINE.
However, the commit bd6b882b2650 ("block/008: check CPU offline failure
due to many IRQs") put _offline_cpu() call in sub-shell, then the set
value to RESTORE_CPUS_ONLINE no longer affects function caller's
environment. This resulted in off-lined CPUs not restored by _cleanup()
when the test case block/008 calls only _offline_cpu() and does not call
_online_cpu().

To fix the issue, set RESTORE_CPUS_ONLINE in _have_cpu_hotplug() in
place of _offline_cpu(). _have_cpu_hotplug() is less likely to be called
in sub-shell. In same manner, do not set RESTORE_CPUS_ONLINE in
_online_cpu() either. Check that RESTORE_CPUS_ONLINE is set in
_offline_cpu() to avoid unexpected CPUs left off-lined. This check also
avoids a shellcheck warning.

Fixes: bd6b882b2650 ("block/008: check CPU offline failure due to many IRQs")
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
---

diff --git a/common/cpuhotplug b/common/cpuhotplug
index 7facd0d..e91c3bc 100644
--- a/common/cpuhotplug
+++ b/common/cpuhotplug
@@ -27,17 +27,20 @@ _have_cpu_hotplug() {
 		SKIP_REASONS+=("CPU hotplugging is not supported")
 		return 1
 	fi
+
+	RESTORE_CPUS_ONLINE=1
 	return 0
 }
 
 _online_cpu() {
-	# shellcheck disable=SC2034
-	RESTORE_CPUS_ONLINE=1
 	echo 1 > "/sys/devices/system/cpu/cpu$1/online"
 }
 
 _offline_cpu() {
-	# shellcheck disable=SC2034
-	RESTORE_CPUS_ONLINE=1
+	if [[ -z ${RESTORE_CPUS_ONLINE} ]]; then
+		echo "offlining cpu but RESTORE_CPUS_ONLINE is not set"
+		return 1
+	fi
+
 	echo 0 > "/sys/devices/system/cpu/cpu$1/online"
 }