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 2023CC3DA7C for ; Thu, 29 Dec 2022 02:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229716AbiL2C3Q (ORCPT ); Wed, 28 Dec 2022 21:29:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232969AbiL2C3M (ORCPT ); Wed, 28 Dec 2022 21:29:12 -0500 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F041812084 for ; Wed, 28 Dec 2022 18:29:11 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id d9so926260pll.9 for ; Wed, 28 Dec 2022 18:29:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=W2hf5CbYXCFQBcGt2m+dp8tLwBISDFTVA7vD9NfSqAA=; b=M7giVCbF43STi477aZF25AQQZ1fTpFXXtJFlPN2G5OMeubAcibZRMF0YH4yEGvGHVF C4AQkTxS+vDgj5F5enKojtYDYqHUNbO2+qPUKJiREGpaG29zBbH6+T1qndmwHYyy0avb QFIggTno4PWiieAP9csHAkUIQx5uhA7/lWhL0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=W2hf5CbYXCFQBcGt2m+dp8tLwBISDFTVA7vD9NfSqAA=; b=YzCXGy5QoCGtpjjdrZ/DJisjeThK7mNs24l+Gf71Vq/6NSxwcGkxfdylqOa9r53efW IdPovjoAWXbboRGZbC/NWK4a4lfAszUVrcU7ar5IJ3JD07uEppjSuCJWfpg1US7Oi7VD ZvIv2tqSYjmDC77sE+N2EgZVUKVKrKkYvZG2ZUq5OQFcB6M5RkoFXyB07f4Ws+9nAYU7 yy0czKsE5mCX6xM3T/K0DqG/vByWAVDZzmBTmisSmOjcsQ4zF8Tv41eJoBo9JUxLsLSe BVYKaNsaXlRRVCPpTwyWd4nBJmGXIU/u1XXhyOkL3rXtX+dSrQaQuMij4DwK+4UUzBjI seqw== X-Gm-Message-State: AFqh2kol36Avsw6c6+JIBSd1T4NkDYwypMlinWkz2Ad7B0DPg+ehIeeG PK9Ao1euwyXKGY+Lv77dbilQwg5vEq8BYm50 X-Google-Smtp-Source: AMrXdXvpfU55xQLInH9yk6pxvFPDMkSgVAfsvIpFXoAIgajHG3GNkXWuzyXM4kqvZZyBmWvCyhBl7g== X-Received: by 2002:a17:90a:64c9:b0:226:2f1c:f167 with SMTP id i9-20020a17090a64c900b002262f1cf167mr1226033pjm.15.1672280951501; Wed, 28 Dec 2022 18:29:11 -0800 (PST) Received: from google.com (KD124209188001.ppp-bb.dion.ne.jp. [124.209.188.1]) by smtp.gmail.com with ESMTPSA id ml4-20020a17090b360400b00225ab429953sm11709989pjb.6.2022.12.28.18.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Dec 2022 18:29:11 -0800 (PST) Date: Thu, 29 Dec 2022 11:29:06 +0900 From: Sergey Senozhatsky To: Namjae Jeon Cc: linux-cifs@vger.kernel.org, smfrench@gmail.com, tom@talpey.com, atteh.mailbox@gmail.com Subject: Re: [PATCH] ksmbd: add max connections parameter Message-ID: References: <20221227145954.9663-1-linkinjeon@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221227145954.9663-1-linkinjeon@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org On (22/12/27 23:59), Namjae Jeon wrote: [..] > csin = KSMBD_TCP_PEER_SOCKADDR(KSMBD_TRANS(t)->conn); > if (kernel_getpeername(client_sk, csin) < 0) { > @@ -239,6 +243,17 @@ static int ksmbd_kthread_fn(void *p) > continue; > } > > + if (server_conf.max_connections) { > + if (atomic_read(&active_num_conn) >= server_conf.max_connections) { > + pr_info("Limit the maximum number of connections(%u)\n", > + atomic_read(&active_num_conn)); > + sock_release(client_sk); > + continue; > + } > + > + atomic_inc(&active_num_conn); > + } This has to be one atomic op: if (atomic_inc_return() >= max_connections) { atomic_dec sock_release continue } Otherwise it's racy and it's possible to have more active connections than the limit. I'd also note that pr_info() is risky there, it would be safer to use rate-limited printk().