[1/4] selftests/livepatch: rework test-klp-callbacks to use completion variables

diff --git a/lib/livepatch/test_klp_callbacks_busy.c b/lib/livepatch/test_klp_callbacks_busy.c
index 40beddf8a0e2..c3df12f47e5e 100644
--- a/lib/livepatch/test_klp_callbacks_busy.c
+++ b/lib/livepatch/test_klp_callbacks_busy.c
@@ -5,34 +5,58 @@ 
 
 #include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/sched.h>
 #include <linux/workqueue.h>
 #include <linux/delay.h>
 
-static int sleep_secs;
-module_param(sleep_secs, int, 0644);
-MODULE_PARM_DESC(sleep_secs, "sleep_secs (default=0)");
+/* load/run-time control from sysfs writer  */
+static bool block_transition;
+module_param(block_transition, bool, 0644);
+MODULE_PARM_DESC(block_transition, "block_transition (default=false)");
 
 static void busymod_work_func(struct work_struct *work);
-static DECLARE_DELAYED_WORK(work, busymod_work_func);
+static DECLARE_WORK(work, busymod_work_func);
+static DECLARE_COMPLETION(busymod_work_complete);
 
 static void busymod_work_func(struct work_struct *work)
 {
-	pr_info("%s, sleeping %d seconds ...\n", __func__, sleep_secs);
-	msleep(sleep_secs * 1000);
+	bool early_complete = block_transition;
+
+	pr_info("%s enter\n", __func__);
+
+	/*
+	 * When blocking the livepatch transition, set completion flag
+	 * early so subsequent test commands see the transition.
+	 */
+	if (early_complete)
+		complete(&busymod_work_complete);
+
+	while (block_transition)
+		msleep(1000);
+
 	pr_info("%s exit\n", __func__);
+
+	/*
+	 * In non-blocking case, wait until we're done to complete to
+	 * ensure kernel log ordering
+	 */
+	if (!early_complete)
+		complete(&busymod_work_complete);
 }
 
 static int test_klp_callbacks_busy_init(void)
 {
 	pr_info("%s\n", __func__);
-	schedule_delayed_work(&work,
-		msecs_to_jiffies(1000 * 0));
+	schedule_work(&work);
+	wait_for_completion(&busymod_work_complete);
+
 	return 0;
 }
 
 static void test_klp_callbacks_busy_exit(void)
 {
-	cancel_delayed_work_sync(&work);
+	block_transition = false;
+	cancel_work_sync(&work);
 	pr_info("%s\n", __func__);
 }
 
diff --git a/tools/testing/selftests/livepatch/test-callbacks.sh b/tools/testing/selftests/livepatch/test-callbacks.sh
index a35289b13c9c..32b57ba07f4f 100755
--- a/tools/testing/selftests/livepatch/test-callbacks.sh
+++ b/tools/testing/selftests/livepatch/test-callbacks.sh
@@ -356,9 +356,7 @@  livepatch: '$MOD_LIVEPATCH': unpatching complete
 echo -n "TEST: multiple target modules ... "
 dmesg -C
 
-load_mod $MOD_TARGET_BUSY sleep_secs=0
-# give $MOD_TARGET_BUSY::busymod_work_func() a chance to run
-sleep 5
+load_mod $MOD_TARGET_BUSY block_transition=N
 load_lp $MOD_LIVEPATCH
 load_mod $MOD_TARGET
 unload_mod $MOD_TARGET
@@ -366,9 +364,9 @@  disable_lp $MOD_LIVEPATCH
 unload_lp $MOD_LIVEPATCH
 unload_mod $MOD_TARGET_BUSY
 
-check_result "% modprobe $MOD_TARGET_BUSY sleep_secs=0
+check_result "% modprobe $MOD_TARGET_BUSY block_transition=N
 $MOD_TARGET_BUSY: ${MOD_TARGET_BUSY}_init
-$MOD_TARGET_BUSY: busymod_work_func, sleeping 0 seconds ...
+$MOD_TARGET_BUSY: busymod_work_func enter
 $MOD_TARGET_BUSY: busymod_work_func exit
 % modprobe $MOD_LIVEPATCH
 livepatch: enabling patch '$MOD_LIVEPATCH'
@@ -404,11 +402,10 @@  livepatch: '$MOD_LIVEPATCH': unpatching complete
 $MOD_TARGET_BUSY: ${MOD_TARGET_BUSY}_exit"
 
 
-
 # TEST: busy target module
 #
 # A similar test as the previous one, but force the "busy" kernel module
-# to do longer work.
+# to block the livepatch transition.
 #
 # The livepatching core will refuse to patch a task that is currently
 # executing a to-be-patched function -- the consistency model stalls the
@@ -417,8 +414,7 @@  $MOD_TARGET_BUSY: ${MOD_TARGET_BUSY}_exit"
 # function for a long time.  Meanwhile, load and unload other target
 # kernel modules while the livepatch transition is in progress.
 #
-# - Load the "busy" kernel module, this time make it do 10 seconds worth
-#   of work.
+# - Load the "busy" kernel module, this time make its work function loop
 #
 # - Meanwhile, the livepatch is loaded.  Notice that the patch
 #   transition does not complete as the targeted "busy" module is
@@ -438,20 +434,23 @@  $MOD_TARGET_BUSY: ${MOD_TARGET_BUSY}_exit"
 echo -n "TEST: busy target module ... "
 dmesg -C
 
-load_mod $MOD_TARGET_BUSY sleep_secs=10
+load_mod $MOD_TARGET_BUSY block_transition=Y
 load_lp_nowait $MOD_LIVEPATCH
-# Don't wait for transition, load $MOD_TARGET while the transition
-# is still stalled in $MOD_TARGET_BUSY::busymod_work_func()
-sleep 5
+
+# Wait until the livepatch reports in-transition state, i.e. that it's
+# stalled on $MOD_TARGET_BUSY::busymod_work_func()
+loop_until 'grep -q '^1$' /sys/kernel/livepatch/$MOD_LIVEPATCH/transition' ||
+	die "failed to stall transition"
+
 load_mod $MOD_TARGET
 unload_mod $MOD_TARGET
 disable_lp $MOD_LIVEPATCH
 unload_lp $MOD_LIVEPATCH
 unload_mod $MOD_TARGET_BUSY
 
-check_result "% modprobe $MOD_TARGET_BUSY sleep_secs=10
+check_result "% modprobe $MOD_TARGET_BUSY block_transition=Y
 $MOD_TARGET_BUSY: ${MOD_TARGET_BUSY}_init
-$MOD_TARGET_BUSY: busymod_work_func, sleeping 10 seconds ...
+$MOD_TARGET_BUSY: busymod_work_func enter
 % modprobe $MOD_LIVEPATCH
 livepatch: enabling patch '$MOD_LIVEPATCH'
 livepatch: '$MOD_LIVEPATCH': initializing patching transition