From patchwork Sat Mar 30 00:08:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Kicinski X-Patchwork-Id: 1070318 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=netronome.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="M6+qONH+"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44WJr73CXPz9sPL for ; Sat, 30 Mar 2019 11:09:27 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730445AbfC3AJ0 (ORCPT ); Fri, 29 Mar 2019 20:09:26 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:44598 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730390AbfC3AJL (ORCPT ); Fri, 29 Mar 2019 20:09:11 -0400 Received: by mail-qt1-f195.google.com with SMTP id w5so4399541qtb.11 for ; Fri, 29 Mar 2019 17:09:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=gFPF0xdLu5V+0kEHHrdxm8rWiz86XO06lZiBRioAcRI=; b=M6+qONH+QmteVwe5RMrKW8JP1cwszZ9jGlNEPDwUU74o9h9+G9R7P7fYlR1aZ3Ni78 xR58IiBkgPlV4+xX8RpfX/E8jB/z6bcNB6FPylKn+vrliUpbNCKMCfbP7iHPfCnsI6uP tzxOCfibwE6yQrW/FxGCPGhOxscjdi/pFI6w5hFX+XlBE71NzAW5UvCG5krNonY0uk8k 3mI2dvd+zt5R2u/Uru0lh7yyS/9ckd7ojW4NvkA7Zze5g3LmVNUCVwj77Q6pMUNOND+n HodpADLdydgdszggckNXsViG/zTC9fSobw6WTSCCeNFMw4cWa12x9jor34keTIm5tJol Ja5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gFPF0xdLu5V+0kEHHrdxm8rWiz86XO06lZiBRioAcRI=; b=Xpn8orjADME+T9BZoqp8T//URQOay8y7w+As2UwVDR+oW0BxYOcDjnURa75o9a7F1P 7NpL8zfE4IGLEtQHYYPC04zQXdcFVoC6HVFwl2mkSiYaid3Drp4ePswkXhaXxa9n1+Rm 4YUWmxiw2UemESL2ToO3hwBzBTMTXHfWEe8auz/CPRUwZVNZK23ZsUT2axX7E0LqMtat aJMW6515+HrxhSGBRoxhrjutxiF/0w3Jt0Be6lpSrGnmuvfSpGRb7BZAeGs0+1VZCegR 6CvYUVEeBzNbY1c0F8oRO8VA2CxxAYmYxdKFsTLIiNeQ5oUPW8RtatgLNla8AZLGr+vq q8Dw== X-Gm-Message-State: APjAAAVessS8G0nrJwKBXt9S8ppVsqN9RtEHF5MlBSVkFKomz6H1qqj2 gNSvm+d+v7nO1hWZMO8E/2o+zg== X-Google-Smtp-Source: APXvYqzpWDD87vmRg/8e2IVWUpzQq6thDRGnAS7KZ8batFaNr7MVg9E8b5r0FA2M+43KSjiQv42iuQ== X-Received: by 2002:ac8:30a1:: with SMTP id v30mr42338564qta.176.1553904550069; Fri, 29 Mar 2019 17:09:10 -0700 (PDT) Received: from jkicinski-Precision-T1700.netronome.com ([66.60.152.14]) by smtp.gmail.com with ESMTPSA id i63sm1996757qkd.82.2019.03.29.17.09.08 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 29 Mar 2019 17:09:09 -0700 (PDT) From: Jakub Kicinski To: peterz@infradead.org, tglx@linutronix.de Cc: ard.biesheuvel@linaro.org, yamada.masahiro@socionext.com, mingo@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, oss-drivers@netronome.com, alexei.starovoitov@gmail.com, Jakub Kicinski , Simon Horman Subject: [PATCH 2/3] locking/static_key: factor out the fast path of static_key_slow_dec() Date: Fri, 29 Mar 2019 17:08:53 -0700 Message-Id: <20190330000854.30142-3-jakub.kicinski@netronome.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190330000854.30142-1-jakub.kicinski@netronome.com> References: <20190330000854.30142-1-jakub.kicinski@netronome.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org static_key_slow_dec() checks if the atomic enable count is larger than 1, and if so there decrements it before taking the jump_label_lock. Move this logic into a helper for reuse in rate limitted keys. Signed-off-by: Jakub Kicinski Reviewed-by: Simon Horman --- kernel/jump_label.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 73bbbaddbd9c..02c3d11264dd 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -202,13 +202,13 @@ void static_key_disable(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_disable); -static void __static_key_slow_dec_cpuslocked(struct static_key *key, - unsigned long rate_limit, - struct delayed_work *work) +static bool static_key_slow_try_dec(struct static_key *key) { int val; - lockdep_assert_cpus_held(); + val = atomic_fetch_add_unless(&key->enabled, -1, 1); + if (val == 1) + return false; /* * The negative count check is valid even when a negative @@ -217,11 +217,18 @@ static void __static_key_slow_dec_cpuslocked(struct static_key *key, * returns is unbalanced, because all other static_key_slow_inc() * instances block while the update is in progress. */ - val = atomic_fetch_add_unless(&key->enabled, -1, 1); - if (val != 1) { - WARN(val < 0, "jump label: negative count!\n"); + WARN(val < 0, "jump label: negative count!\n"); + return true; +} + +static void __static_key_slow_dec_cpuslocked(struct static_key *key, + unsigned long rate_limit, + struct delayed_work *work) +{ + lockdep_assert_cpus_held(); + + if (static_key_slow_try_dec(key)) return; - } jump_label_lock(); if (atomic_dec_and_test(&key->enabled)) {