diff options
Diffstat (limited to 'include/linux/once.h')
| -rw-r--r-- | include/linux/once.h | 38 |
1 files changed, 32 insertions, 6 deletions
diff --git a/include/linux/once.h b/include/linux/once.h index 9225ee6d96c7..30346fcdc799 100644 --- a/include/linux/once.h +++ b/include/linux/once.h @@ -5,9 +5,17 @@ #include <linux/types.h> #include <linux/jump_label.h> +/* Helpers used from arbitrary contexts. + * Hard irqs are blocked, be cautious. + */ bool __do_once_start(bool *done, unsigned long *flags); void __do_once_done(bool *done, struct static_key_true *once_key, - unsigned long *flags); + unsigned long *flags, struct module *mod); + +/* Variant for process contexts only. */ +bool __do_once_sleepable_start(bool *done); +void __do_once_sleepable_done(bool *done, struct static_key_true *once_key, + struct module *mod); /* Call a function exactly once. The idea of DO_ONCE() is to perform * a function call such as initialization of random seeds, etc, only @@ -16,7 +24,7 @@ void __do_once_done(bool *done, struct static_key_true *once_key, * out the condition into a nop. DO_ONCE() guarantees type safety of * arguments! * - * Not that the following is not equivalent ... + * Note that the following is not equivalent ... * * DO_ONCE(func, arg); * DO_ONCE(func, arg); @@ -38,7 +46,7 @@ void __do_once_done(bool *done, struct static_key_true *once_key, #define DO_ONCE(func, ...) \ ({ \ bool ___ret = false; \ - static bool ___done = false; \ + static bool __section(".data..once") ___done = false; \ static DEFINE_STATIC_KEY_TRUE(___once_key); \ if (static_branch_unlikely(&___once_key)) { \ unsigned long ___flags; \ @@ -46,15 +54,33 @@ void __do_once_done(bool *done, struct static_key_true *once_key, if (unlikely(___ret)) { \ func(__VA_ARGS__); \ __do_once_done(&___done, &___once_key, \ - &___flags); \ + &___flags, THIS_MODULE); \ } \ } \ ___ret; \ }) +/* Variant of DO_ONCE() for process/sleepable contexts. */ +#define DO_ONCE_SLEEPABLE(func, ...) \ + ({ \ + bool ___ret = false; \ + static bool __section(".data..once") ___done = false; \ + static DEFINE_STATIC_KEY_TRUE(___once_key); \ + if (static_branch_unlikely(&___once_key)) { \ + ___ret = __do_once_sleepable_start(&___done); \ + if (unlikely(___ret)) { \ + func(__VA_ARGS__); \ + __do_once_sleepable_done(&___done, &___once_key,\ + THIS_MODULE); \ + } \ + } \ + ___ret; \ + }) + #define get_random_once(buf, nbytes) \ DO_ONCE(get_random_bytes, (buf), (nbytes)) -#define get_random_once_wait(buf, nbytes) \ - DO_ONCE(get_random_bytes_wait, (buf), (nbytes)) \ + +#define get_random_sleepable_once(buf, nbytes) \ + DO_ONCE_SLEEPABLE(get_random_bytes, (buf), (nbytes)) #endif /* _LINUX_ONCE_H */ |