Merge tag 'u-boot-watchdog-20250516' of https://source.denx.de/u-boot/custodians/u-boot-watchdog

CI: https://dev.azure.com/sr0718/u-boot/_build/results?buildId=393&view=results

- make cyclic_(un)register idempotent

2 files changed, 30 insertions, 0 deletions

diff --git a/common/cyclic.c b/common/cyclic.c
index b695f092f52..ec952a01ee1 100644
--- a/common/cyclic.c
+++ b/common/cyclic.c
@@ -28,9 +28,23 @@ struct hlist_head *cyclic_get_list(void)
 	return (struct hlist_head *)&gd->cyclic_list;
 }
 
+static bool cyclic_is_registered(const struct cyclic_info *cyclic)
+{
+	const struct cyclic_info *c;
+
+	hlist_for_each_entry(c, cyclic_get_list(), list) {
+		if (c == cyclic)
+			return true;
+	}
+
+	return false;
+}
+
 void cyclic_register(struct cyclic_info *cyclic, cyclic_func_t func,
 		     uint64_t delay_us, const char *name)
 {
+	cyclic_unregister(cyclic);
+
 	memset(cyclic, 0, sizeof(*cyclic));
 
 	/* Store values in struct */
@@ -43,6 +57,9 @@ void cyclic_register(struct cyclic_info *cyclic, cyclic_func_t func,
 
 void cyclic_unregister(struct cyclic_info *cyclic)
 {
+	if (!cyclic_is_registered(cyclic))
+		return;
+
 	hlist_del(&cyclic->list);
 }
 
diff --git a/doc/develop/cyclic.rst b/doc/develop/cyclic.rst
index 6f1da6f0d9b..a99b17052f5 100644
--- a/doc/develop/cyclic.rst
+++ b/doc/develop/cyclic.rst
@@ -54,3 +54,16 @@ responsible for calling all registered cyclic functions, into the
 common schedule() function. This guarantees that cyclic_run() is
 executed very often, which is necessary for the cyclic functions to
 get scheduled and executed at their configured periods.
+
+Idempotence
+-----------
+
+Both the cyclic_register() and cyclic_unregister() functions are safe
+to call on any struct cyclic_info, regardless of whether that instance
+is already registered or not.
+
+More specifically, calling cyclic_unregister() with a cyclic_info
+which is not currently registered is a no-op, while calling
+cyclic_register() with a cyclic_info which is currently registered
+results in it being automatically unregistered, and then registered
+with the new callback function and timeout parameters.