Add config_intrhook_oneshot(): schedule an intrhook function and unregister

it automatically after it runs.

The config_intrhook mechanism allows a driver to stall the boot process
until device(s) required for booting are available, by not allowing system
inits to proceed until all intrhook functions have been unregistered.
Virtually all existing code simply unregisters from within the hook function
when it gets called.

This new function makes that common usage more convenient. Instead of
allocating and filling in a struct, passing it to a function that might (in
theory) fail, and checking the return code, now a driver can simply call
this cannot-fail routine, passing just the intrhook function and its arg.

Differential Revision:	https://reviews.freebsd.org/D11963

(cherry picked from commit 3dabf0d77785be405b3aa27de0590c5addd533dc)

1 files changed, 5 insertions, 2 deletions

diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index 7124349..c9478fd 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -400,13 +400,16 @@ struct tunable_str {
 #define	TUNABLE_STR_FETCH(path, var, size)			\
 	getenv_string((path), (var), (size))
 
+typedef void (*ich_func_t)(void *_arg);
+
 struct intr_config_hook {
 	TAILQ_ENTRY(intr_config_hook) ich_links;
-	void	(*ich_func)(void *arg);
-	void	*ich_arg;
+	ich_func_t	ich_func;
+	void		*ich_arg;
 };
 
 int	config_intrhook_establish(struct intr_config_hook *hook);
 void	config_intrhook_disestablish(struct intr_config_hook *hook);
+void	config_intrhook_oneshot(ich_func_t _func, void *_arg);
 
 #endif /* !_SYS_KERNEL_H_*/