From 2bce6368c46b835a133f7f4946eea9c4513828dd Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Tue, 24 Oct 2023 14:46:58 -0400 Subject: [PATCH] closures: Better memory barriers atomic_(dec|sub)_return_release() are a thing now - use them. Also, delete the useless barrier in set_closure_fn(): it's redundant with the memory barrier in closure_put(0. Since closure_put() would now otherwise just have a release barrier, we also need a new barrier when the ref hits 0 - smp_acquire__after_ctrl_dep(). Signed-off-by: Kent Overstreet --- include/linux/closure.h | 2 -- lib/closure.c | 6 ++++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/closure.h b/include/linux/closure.h index 722a586bb224..bdab17050bc8 100644 --- a/include/linux/closure.h +++ b/include/linux/closure.h @@ -233,8 +233,6 @@ static inline void set_closure_fn(struct closure *cl, closure_fn *fn, closure_set_ip(cl); cl->fn = fn; cl->wq = wq; - /* between atomic_dec() in closure_put() */ - smp_mb__before_atomic(); } static inline void closure_queue(struct closure *cl) diff --git a/lib/closure.c b/lib/closure.c index 0855e698ced1..501dfa277b59 100644 --- a/lib/closure.c +++ b/lib/closure.c @@ -21,6 +21,8 @@ static inline void closure_put_after_sub(struct closure *cl, int flags) BUG_ON(!r && (flags & ~CLOSURE_DESTRUCTOR)); if (!r) { + smp_acquire__after_ctrl_dep(); + if (cl->fn && !(flags & CLOSURE_DESTRUCTOR)) { atomic_set(&cl->remaining, CLOSURE_REMAINING_INITIALIZER); @@ -43,7 +45,7 @@ static inline void closure_put_after_sub(struct closure *cl, int flags) /* For clearing flags with the same atomic op as a put */ void closure_sub(struct closure *cl, int v) { - closure_put_after_sub(cl, atomic_sub_return(v, &cl->remaining)); + closure_put_after_sub(cl, atomic_sub_return_release(v, &cl->remaining)); } EXPORT_SYMBOL(closure_sub); @@ -52,7 +54,7 @@ EXPORT_SYMBOL(closure_sub); */ void closure_put(struct closure *cl) { - closure_put_after_sub(cl, atomic_dec_return(&cl->remaining)); + closure_put_after_sub(cl, atomic_dec_return_release(&cl->remaining)); } EXPORT_SYMBOL(closure_put); -- 2.25.1