10.12.2021 21:32, Rafael J. Wysocki пишет:
On Fri, Nov 26, 2021 at 7:02 PM Dmitry Osipenko <digetx@xxxxxxxxx> wrote:Emit warning if unregister_restart_handler() fails since it never should fail. This will ease further API development by catching mistakes early. Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> --- kernel/reboot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/reboot.c b/kernel/reboot.c index e6659ae329f1..f0e7b9c13f6b 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -210,7 +210,7 @@ EXPORT_SYMBOL(register_restart_handler); */ int unregister_restart_handler(struct notifier_block *nb) { - return atomic_notifier_chain_unregister(&restart_handler_list, nb); + return WARN_ON(atomic_notifier_chain_unregister(&restart_handler_list, nb));The only reason why it can fail is if the object pointed to by nb is not in the chain.
I had exactly this case where object wasn't in the chain due to a bug and this warning was very helpful.
Why WARN() about this? And what about systems with panic_on_warn set?
That warning condition will never happen normally, only when something is seriously wrong. Those systems with panic_on_warn will get what was they asked for.
