diff --git a/include/linux/closure.h b/include/linux/closure.h index 99155df162d0..59b8c06b11ff 100644 --- a/include/linux/closure.h +++ b/include/linux/closure.h @@ -284,6 +284,21 @@ static inline void closure_get(struct closure *cl) #endif } +/** + * closure_get_not_zero + */ +static inline bool closure_get_not_zero(struct closure *cl) +{ + unsigned old = atomic_read(&cl->remaining); + do { + if (!(old & CLOSURE_REMAINING_MASK)) + return false; + + } while (!atomic_try_cmpxchg_acquire(&cl->remaining, &old, old + 1)); + + return true; +} + /** * closure_init - Initialize a closure, setting the refcount to 1 * @cl: closure to initialize @@ -310,6 +325,12 @@ static inline void closure_init_stack(struct closure *cl) atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER); } +static inline void closure_init_stack_release(struct closure *cl) +{ + memset(cl, 0, sizeof(struct closure)); + atomic_set_release(&cl->remaining, CLOSURE_REMAINING_INITIALIZER); +} + /** * closure_wake_up - wake up all closures on a wait list, * with memory barrier @@ -355,6 +376,8 @@ do { \ */ #define closure_return(_cl) continue_at((_cl), NULL, NULL) +void closure_return_sync(struct closure *cl); + /** * continue_at_nobarrier - jump to another function without barrier * diff --git a/lib/closure.c b/lib/closure.c index 2e1ee9fdec08..c971216d9d77 100644 --- a/lib/closure.c +++ b/lib/closure.c @@ -13,7 +13,7 @@ #include #include -static inline void closure_put_after_sub(struct closure *cl, int flags) +static inline void closure_put_after_sub_checks(int flags) { int r = flags & CLOSURE_REMAINING_MASK; @@ -22,12 +22,17 @@ static inline void closure_put_after_sub(struct closure *cl, int flags) flags & CLOSURE_GUARD_MASK, (unsigned) __fls(r))) r &= ~CLOSURE_GUARD_MASK; - if (!r) { - smp_acquire__after_ctrl_dep(); + WARN(!r && (flags & ~CLOSURE_DESTRUCTOR), + "closure ref hit 0 with incorrect flags set: %x (%u)", + flags & ~CLOSURE_DESTRUCTOR, (unsigned) __fls(flags)); +} - WARN(flags & ~CLOSURE_DESTRUCTOR, - "closure ref hit 0 with incorrect flags set: %x (%u)", - flags & ~CLOSURE_DESTRUCTOR, (unsigned) __fls(flags)); +static inline void closure_put_after_sub(struct closure *cl, int flags) +{ + closure_put_after_sub_checks(flags); + + if (!(flags & CLOSURE_REMAINING_MASK)) { + smp_acquire__after_ctrl_dep(); cl->closure_get_happened = false; @@ -145,6 +150,41 @@ void __sched __closure_sync(struct closure *cl) } EXPORT_SYMBOL(__closure_sync); +/* + * closure_return_sync - finish running a closure, synchronously (i.e. waiting + * for outstanding get()s to finish) and returning once closure refcount is 0. + * + * Unlike closure_sync() this doesn't reinit the ref to 1; subsequent + * closure_get_not_zero() calls waill fail. + */ +void __sched closure_return_sync(struct closure *cl) +{ + struct closure_syncer s = { .task = current }; + + cl->s = &s; + set_closure_fn(cl, closure_sync_fn, NULL); + + unsigned flags = atomic_sub_return_release(1 + CLOSURE_RUNNING - CLOSURE_DESTRUCTOR, + &cl->remaining); + + closure_put_after_sub_checks(flags); + + if (unlikely(flags & CLOSURE_REMAINING_MASK)) { + while (1) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (s.done) + break; + schedule(); + } + + __set_current_state(TASK_RUNNING); + } + + if (cl->parent) + closure_put(cl->parent); +} +EXPORT_SYMBOL(closure_return_sync); + int __sched __closure_sync_timeout(struct closure *cl, unsigned long timeout) { struct closure_syncer s = { .task = current };