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 X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65D0EC48BD6 for ; Wed, 26 Jun 2019 01:36:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 310BA20883 for ; Wed, 26 Jun 2019 01:36:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LEllaoY4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726664AbfFZBg6 (ORCPT ); Tue, 25 Jun 2019 21:36:58 -0400 Received: from mail-yb1-f194.google.com ([209.85.219.194]:43123 "EHLO mail-yb1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726647AbfFZBg4 (ORCPT ); Tue, 25 Jun 2019 21:36:56 -0400 Received: by mail-yb1-f194.google.com with SMTP id 5so370591ybj.10 for ; Tue, 25 Jun 2019 18:36:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HTYwKuXPT5ALk6Fdrn6IzuSHliH6LA0lPjX35sqNWXk=; b=LEllaoY4m3xHWsTf7N+j4EKZmEHnZurpJaQ4DfOFpDq5VCrh/Gz2Ay+qnaw+/VsjPx NdSVVQpJr40BZE6Igeny8QytRZGs2Q/pWaDuYl3MfRlk2BCtw4EoH94czkdBkZEkG2U2 pEpjPktRmpofIUWGYnET5+J9dWWu1Nr5Z5HkvrveWaTFPl4wzPfG8fKjVuQDtov0ywD4 yJc4bdyE/f1Z5EZXXaOuPkm/TbXG//FaJ9D1n/wYXeX9UeS6Nl8vpsriv+kRzCGIiI80 v6GAgaz0IchTKo6kTwjApTZ4Ga/8zRr/MuhlYpouM1wn78rpueWlK4a5wddrIlqHdaUd cyhw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HTYwKuXPT5ALk6Fdrn6IzuSHliH6LA0lPjX35sqNWXk=; b=bIqF7DKDcMRQmYC0u/qqeIrEATFYFQU/g2o2Y/oeUOXXxLupO+xkfDF5+ZO71rsBSt oXBOgDYATpITmw/v7u3FwkYkWnGisJjlZX4g9yim2yPrJwesUXGSDPJSbr172orA344l bcQ2zSVHjSR6Ts5xk9hyhHq8qPMTB6jfaXEeCW/rzgxaAljDEk76AooGPqzP66x+5B28 cdumgBHzDEyoNqcWm9dQEf4VkezyR7hbQFp0irz0M9BvaOA/4hyyYOfeb3ZVr115q1p+ /BGFminSQlM753eC0c0v/K9VKY6oolrOuLYdJXZXUZgn3b8qVJKsobS3j0arP2eo3LLx 5ulA== X-Gm-Message-State: APjAAAVTNhBn96djrtUcQViRf9Zq6+/c3mTZPbSyn2euX0J6aPPnRr4K iA/2WFymWH9AHrul9IlOJd67goDB X-Google-Smtp-Source: APXvYqwPIXbfl9c6ilJXZ7bKfPEIfqEnq2u/iR4ITvDGhpiD46M/qh69iWgzBx664YD3WzLqmTCALg== X-Received: by 2002:a25:550b:: with SMTP id j11mr940441ybb.223.1561513014109; Tue, 25 Jun 2019 18:36:54 -0700 (PDT) Received: from mail-yb1-f180.google.com (mail-yb1-f180.google.com. [209.85.219.180]) by smtp.gmail.com with ESMTPSA id 15sm4000069ywo.74.2019.06.25.18.36.52 for (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 25 Jun 2019 18:36:53 -0700 (PDT) Received: by mail-yb1-f180.google.com with SMTP id n3so405354ybn.0 for ; Tue, 25 Jun 2019 18:36:52 -0700 (PDT) X-Received: by 2002:a25:21c2:: with SMTP id h185mr1028553ybh.125.1561513012633; Tue, 25 Jun 2019 18:36:52 -0700 (PDT) MIME-Version: 1.0 References: <20190625175948.24771-1-ivan.khoronzhuk@linaro.org> <20190625175948.24771-2-ivan.khoronzhuk@linaro.org> In-Reply-To: <20190625175948.24771-2-ivan.khoronzhuk@linaro.org> From: Willem de Bruijn Date: Tue, 25 Jun 2019 21:36:15 -0400 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4 net-next 1/4] net: core: page_pool: add user cnt preventing pool deletion To: Ivan Khoronzhuk Cc: David Miller , grygorii.strashko@ti.com, hawk@kernel.org, brouer@redhat.com, saeedm@mellanox.com, leon@kernel.org, Alexei Starovoitov , linux-kernel , linux-omap@vger.kernel.org, xdp-newbies@vger.kernel.org, ilias.apalodimas@linaro.org, Network Development , Daniel Borkmann , jakub.kicinski@netronome.com, John Fastabend Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jun 25, 2019 at 2:00 PM Ivan Khoronzhuk wrote: > > Add user counter allowing to delete pool only when no users. > It doesn't prevent pool from flush, only prevents freeing the > pool instance. Helps when no need to delete the pool and now > it's user responsibility to free it by calling page_pool_free() > while destroying procedure. It also makes to use page_pool_free() > explicitly, not fully hidden in xdp unreg, which looks more > correct after page pool "create" routine. > > Signed-off-by: Ivan Khoronzhuk > --- > diff --git a/include/net/page_pool.h b/include/net/page_pool.h > index f07c518ef8a5..1ec838e9927e 100644 > --- a/include/net/page_pool.h > +++ b/include/net/page_pool.h > @@ -101,6 +101,7 @@ struct page_pool { > struct ptr_ring ring; > > atomic_t pages_state_release_cnt; > + atomic_t user_cnt; refcount_t? > }; > > struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); > @@ -183,6 +184,12 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page) > return page->dma_addr; > } > > +/* used to prevent pool from deallocation */ > +static inline void page_pool_get(struct page_pool *pool) > +{ > + atomic_inc(&pool->user_cnt); > +} > + > static inline bool is_page_pool_compiled_in(void) > { > #ifdef CONFIG_PAGE_POOL > diff --git a/net/core/page_pool.c b/net/core/page_pool.c > index b366f59885c1..169b0e3c870e 100644 > --- a/net/core/page_pool.c > +++ b/net/core/page_pool.c > @@ -48,6 +48,7 @@ static int page_pool_init(struct page_pool *pool, > return -ENOMEM; > > atomic_set(&pool->pages_state_release_cnt, 0); > + atomic_set(&pool->user_cnt, 0); > > if (pool->p.flags & PP_FLAG_DMA_MAP) > get_device(pool->p.dev); > @@ -70,6 +71,8 @@ struct page_pool *page_pool_create(const struct page_pool_params *params) > kfree(pool); > return ERR_PTR(err); > } > + > + page_pool_get(pool); > return pool; > } > EXPORT_SYMBOL(page_pool_create); > @@ -356,6 +359,10 @@ static void __warn_in_flight(struct page_pool *pool) > > void __page_pool_free(struct page_pool *pool) > { > + /* free only if no users */ > + if (!atomic_dec_and_test(&pool->user_cnt)) > + return; > + > WARN(pool->alloc.count, "API usage violation"); > WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty"); > > diff --git a/net/core/xdp.c b/net/core/xdp.c > index 829377cc83db..04bdcd784d2e 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -372,6 +372,9 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, > > mutex_unlock(&mem_id_lock); > > + if (type == MEM_TYPE_PAGE_POOL) > + page_pool_get(xdp_alloc->page_pool); > + need an analogous page_pool_put in xdp_rxq_info_unreg_mem_model? mlx5 does not use that inverse function, but intel drivers do. > trace_mem_connect(xdp_alloc, xdp_rxq); > return 0; > err: > -- > 2.17.1 >