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 85F22C433F5 for ; Mon, 16 May 2022 16:09:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245716AbiEPQJq (ORCPT ); Mon, 16 May 2022 12:09:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242024AbiEPQJo (ORCPT ); Mon, 16 May 2022 12:09:44 -0400 Received: from mail-qt1-f171.google.com (mail-qt1-f171.google.com [209.85.160.171]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B169537BE6 for ; Mon, 16 May 2022 09:09:36 -0700 (PDT) Received: by mail-qt1-f171.google.com with SMTP id h3so12430549qtn.4 for ; Mon, 16 May 2022 09:09:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=5A3fC3LG9xhFT5OmLJx0Vov2wbp1md3QmcKxPsHHehk=; b=RMtITERx0KHzjfeMFcYUQ5YwBoiNb9R11NyYH1Id6J8V+h+/L6hyhds+eA/ilaJS+b YRIZN7EhCvti69lMKpEWUDxLpweg6Ds6kamzkC77wiVrVWaGJvpn2aeXEVcWN3UQG9ns um5LjonHGlZeIggbpQJv+xT2HdGW7DL+bU7UlgPsbK8zmQAAjuIbeD/w3U/pAOi1IxAc YEZqd7r571DrtNXlOYKamX6Es3tWY2z2J0eqfPWdbgvDezCJOSShMAACxzuJWwdD4FUw ZNjtzSn5iJ/CA79eO6OKioVysDODsqOayoLGxCLwDaMT2AzhyHHWlG4JkZ9lWEfnlUEW mu6Q== X-Gm-Message-State: AOAM533Eg8EXkBg+6Xtf2Bl8NNH3Ws+i7sEyuef7X4AF8n417OYzPWkT g9PSnUtVnvf0qyKOzw9XyqU= X-Google-Smtp-Source: ABdhPJxaLYoSk22p+9ELkyOUmLJ2arHz6w3RoUHNqaL/xzMHVVyRQRoHCPV4tNU1ot7PnY88+ahosw== X-Received: by 2002:ac8:57c8:0:b0:2f3:bdc8:ede5 with SMTP id w8-20020ac857c8000000b002f3bdc8ede5mr15624403qta.458.1652717375606; Mon, 16 May 2022 09:09:35 -0700 (PDT) Received: from dev0025.ash9.facebook.com (fwdproxy-ash-015.fbsv.net. [2a03:2880:20ff:f::face:b00c]) by smtp.gmail.com with ESMTPSA id 143-20020a370995000000b0069fc13ce207sm5895359qkj.56.2022.05.16.09.09.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 May 2022 09:09:35 -0700 (PDT) Date: Mon, 16 May 2022 09:09:32 -0700 From: David Vernet To: Joanne Koong Cc: bpf@vger.kernel.org, andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net Subject: Re: [PATCH bpf-next v4 3/6] bpf: Dynptr support for ring buffers Message-ID: <20220516160932.mttpfphr6rkm4ve7@dev0025.ash9.facebook.com> References: <20220509224257.3222614-1-joannelkoong@gmail.com> <20220509224257.3222614-4-joannelkoong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220509224257.3222614-4-joannelkoong@gmail.com> User-Agent: NeoMutt/20211029 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, May 09, 2022 at 03:42:54PM -0700, Joanne Koong wrote: > Currently, our only way of writing dynamically-sized data into a ring > buffer is through bpf_ringbuf_output but this incurs an extra memcpy > cost. bpf_ringbuf_reserve + bpf_ringbuf_commit avoids this extra > memcpy, but it can only safely support reservation sizes that are > statically known since the verifier cannot guarantee that the bpf > program won’t access memory outside the reserved space. > > The bpf_dynptr abstraction allows for dynamically-sized ring buffer > reservations without the extra memcpy. > > There are 3 new APIs: > > long bpf_ringbuf_reserve_dynptr(void *ringbuf, u32 size, u64 flags, struct bpf_dynptr *ptr); > void bpf_ringbuf_submit_dynptr(struct bpf_dynptr *ptr, u64 flags); > void bpf_ringbuf_discard_dynptr(struct bpf_dynptr *ptr, u64 flags); > > These closely follow the functionalities of the original ringbuf APIs. > For example, all ringbuffer dynptrs that have been reserved must be > either submitted or discarded before the program exits. > > Signed-off-by: Joanne Koong Looks good! Acked-by: David Vernet