From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 705EEC4167B for ; Tue, 31 Oct 2023 16:36:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346682AbjJaQgw (ORCPT ); Tue, 31 Oct 2023 12:36:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346693AbjJaQgJ (ORCPT ); Tue, 31 Oct 2023 12:36:09 -0400 Received: from out-185.mta1.migadu.com (out-185.mta1.migadu.com [IPv6:2001:41d0:203:375::b9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51E6010F3 for ; Tue, 31 Oct 2023 09:33:33 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1698769504; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uqS4BEhMwIAHIltUcK28FXSk9fUQ8Tpbi82lSqupklQ=; b=K5Mp9HWE+8OC7T5meVobLfJ1oI2LVTPbvxBoqgjHcOCONI7BRC5vOSnUg9GleKvbB4J/2z L6LeEXjLzfOQMxtlyd3dcCu2phfMvDR6Dz+2DagJft6vfXhQM6ufOLoiTQhICndN4WDQ0a PFRdpoinlHfyiB6W41aR/04eh5AMpvY= From: Kent Overstreet To: linux-bcache@vger.kernel.org, linux-bcachefs@vger.kernel.org Cc: Kent Overstreet Subject: [PATCH 1/2] closures: Better memory barriers Date: Tue, 31 Oct 2023 12:24:51 -0400 Message-ID: <20231031162454.3761482-2-kent.overstreet@linux.dev> In-Reply-To: <20231031162454.3761482-1-kent.overstreet@linux.dev> References: <20231031162454.3761482-1-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org 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); -- 2.42.0