From patchwork Mon Oct 24 11:29:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 9961 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:6687:0:0:0:0:0 with SMTP id l7csp609588wru; Mon, 24 Oct 2022 12:11:17 -0700 (PDT) X-Google-Smtp-Source: AMsMyM77oEqp93chCn6Fmsx7AoiXdWuEyChE3S0UwrFxXyrpvNlE6DYjn8cbV2JlWRomR4zhUDA0 X-Received: by 2002:a63:e806:0:b0:44b:d45b:b8a2 with SMTP id s6-20020a63e806000000b0044bd45bb8a2mr29128519pgh.14.1666638677112; Mon, 24 Oct 2022 12:11:17 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1666638677; cv=none; d=google.com; s=arc-20160816; b=mafW82HnMkMqqx9iGDUhj10bMcPFkY9yv+fs53VKl/WfV4UvJMG9EKBg0g7yB/ISQT wMWCs1WjHr9fsvPRy/CcNz2wDmueeWnEPI0yI8daZqK+Q4EphkgJxXW8V8Aa3HkfrthR tnmpLAU0pa3zEiPUIlMGp9+6crQ4GBORNR7XZwXshDK79ySEVVj1e7iynIJVvM6AXicj sgbian1/YPXRZ746e0zj0+NWzMlReMUXx8cRcKhWOWlzNfF8VwPZIMLkgYrug65+ufgu j3RUBWW5VuOb3PeetJLblxTGPXcxjz25YwafQFTe+cYopEMrsumNJkWIe3wuDyWdSJ3P YVGg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=eQ/4xHRs+Q7elplKN9RkdFmQtjO9CIDtktF1CipmilM=; b=nHGNavisfKV1ek3uj7va97hXQlkZkjihaQLyeevjVUJLsxGWSNPuX45A6HKDfIBEKi PkG0Bglx/qUFmYXrZNsp8hvRTpYdgpg5TucuDuf2cWnsh4yc2HOCn2jg+08R7XlPinmF SNTgwG/u5fubUEXCR78ABwRFc9qg6tykuCLJGOAliewjezA8xQYXwzzookRYZ+1DEZps VvGYzkTAJt6nfDiOQDVgJQeTB0CYaVEeNP6KF0OoKr66GVTlVPrUf5qcP4LYlOPBDoUE wZ+JPVjNwq3I6VdQoJT2qtRNGTp6zTAkc408PuRhThg2DUvFd3na+pcbMgjpbAHjmsSc gbGQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=wmvxrwO1; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id q20-20020a638c54000000b0046f0ae1bb8fsi268783pgn.785.2022.10.24.12.11.04; Mon, 24 Oct 2022 12:11:17 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=wmvxrwO1; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232516AbiJXTKi (ORCPT + 99 others); Mon, 24 Oct 2022 15:10:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232364AbiJXTKF (ORCPT ); Mon, 24 Oct 2022 15:10:05 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 698364685E; Mon, 24 Oct 2022 10:49:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A4AD5B8197C; Mon, 24 Oct 2022 12:42:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B2BCC433C1; Mon, 24 Oct 2022 12:41:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666615319; bh=wRvDf88Vd8lClG7OFGwQVtj0WQgpoKy44Rp3UnjATww=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wmvxrwO1++hPfV5+U9fr2ZQCgsHsU2v9ngWPzwzi2D8nkNauJx22Vxp7s5p0af7S+ srtNpGwo2wiB5izAGYgulOOl0fHdQbKAYxU8GKJDEDCkv1qz6DpIlqtDCm3YwKteRx MKqhr8eN25VLN2CY4LVzoMazXNvcRTUtvvmHAXe0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christophe Leroy , Eric Dumazet , Willy Tarreau , "David S. Miller" , Sasha Levin Subject: [PATCH 5.15 206/530] once: add DO_ONCE_SLOW() for sleepable contexts Date: Mon, 24 Oct 2022 13:29:10 +0200 Message-Id: <20221024113054.391630009@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024113044.976326639@linuxfoundation.org> References: <20221024113044.976326639@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747597317401478797?= X-GMAIL-MSGID: =?utf-8?q?1747597317401478797?= From: Eric Dumazet [ Upstream commit 62c07983bef9d3e78e71189441e1a470f0d1e653 ] Christophe Leroy reported a ~80ms latency spike happening at first TCP connect() time. This is because __inet_hash_connect() uses get_random_once() to populate a perturbation table which became quite big after commit 4c2c8f03a5ab ("tcp: increase source port perturb table to 2^16") get_random_once() uses DO_ONCE(), which block hard irqs for the duration of the operation. This patch adds DO_ONCE_SLOW() which uses a mutex instead of a spinlock for operations where we prefer to stay in process context. Then __inet_hash_connect() can use get_random_slow_once() to populate its perturbation table. Fixes: 4c2c8f03a5ab ("tcp: increase source port perturb table to 2^16") Fixes: 190cc82489f4 ("tcp: change source port randomizarion at connect() time") Reported-by: Christophe Leroy Link: https://lore.kernel.org/netdev/CANn89iLAEYBaoYajy0Y9UmGFff5GPxDUoG-ErVB2jDdRNQ5Tug@mail.gmail.com/T/#t Signed-off-by: Eric Dumazet Cc: Willy Tarreau Tested-by: Christophe Leroy Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/linux/once.h | 28 ++++++++++++++++++++++++++++ lib/once.c | 30 ++++++++++++++++++++++++++++++ net/ipv4/inet_hashtables.c | 4 ++-- 3 files changed, 60 insertions(+), 2 deletions(-) diff --git a/include/linux/once.h b/include/linux/once.h index d361fb14ac3a..1528625087b6 100644 --- a/include/linux/once.h +++ b/include/linux/once.h @@ -5,10 +5,18 @@ #include #include +/* 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, struct module *mod); +/* Variant for process contexts only. */ +bool __do_once_slow_start(bool *done); +void __do_once_slow_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 * once, where DO_ONCE() can live in the fast-path. After @func has @@ -52,9 +60,29 @@ void __do_once_done(bool *done, struct static_key_true *once_key, ___ret; \ }) +/* Variant of DO_ONCE() for process/sleepable contexts. */ +#define DO_ONCE_SLOW(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_slow_start(&___done); \ + if (unlikely(___ret)) { \ + func(__VA_ARGS__); \ + __do_once_slow_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_slow_once(buf, nbytes) \ + DO_ONCE_SLOW(get_random_bytes, (buf), (nbytes)) + #endif /* _LINUX_ONCE_H */ diff --git a/lib/once.c b/lib/once.c index 59149bf3bfb4..351f66aad310 100644 --- a/lib/once.c +++ b/lib/once.c @@ -66,3 +66,33 @@ void __do_once_done(bool *done, struct static_key_true *once_key, once_disable_jump(once_key, mod); } EXPORT_SYMBOL(__do_once_done); + +static DEFINE_MUTEX(once_mutex); + +bool __do_once_slow_start(bool *done) + __acquires(once_mutex) +{ + mutex_lock(&once_mutex); + if (*done) { + mutex_unlock(&once_mutex); + /* Keep sparse happy by restoring an even lock count on + * this mutex. In case we return here, we don't call into + * __do_once_done but return early in the DO_ONCE_SLOW() macro. + */ + __acquire(once_mutex); + return false; + } + + return true; +} +EXPORT_SYMBOL(__do_once_slow_start); + +void __do_once_slow_done(bool *done, struct static_key_true *once_key, + struct module *mod) + __releases(once_mutex) +{ + *done = true; + mutex_unlock(&once_mutex); + once_disable_jump(once_key, mod); +} +EXPORT_SYMBOL(__do_once_slow_done); diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 26c4dd4ec459..ce6a3873f89e 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -771,8 +771,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, if (likely(remaining > 1)) remaining &= ~1U; - net_get_random_once(table_perturb, - INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb)); + get_random_slow_once(table_perturb, + INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb)); index = port_offset & (INET_TABLE_PERTURB_SIZE - 1); offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32);