From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 40A641A262D; Fri, 3 Apr 2026 23:56:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775260598; cv=none; b=H6MkiSIzQ/O5YPTZ8a9IjlfsHBshjCjysOizoPr3QI7un8GapYFXcFthfJz4Vn2HRwlb5vtiKIzvcizatQe5gDSgMGEwCZkVgaW0HsKIiJrFHnIYE2fMnBjGnju43tBQ919Oi4eGcJ6knG31QdjMvNWGsMw5KnraYGF+ctsvQ9c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775260598; c=relaxed/simple; bh=UTBAkQ9neJE5ofzAe8EoJOdScc3B7H+1wVjcdejfLXE=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=nnHlTmw9ffp8u30PndwqN7n6gvVpvUIYYh270gEQpXVSl/nr22IRlyULaD499zPoUSwA+rY6s1X4gx6NbeM2zpC9j5kwvq7VxRBRttHQPeIq+ZHIXQU/lCTjzcqgGWSH7XajD7xAe4XoXsvVmSY+KZ81qpDTDD66VHu/2n1iSy4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=msMw8Xsx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="msMw8Xsx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 756A1C4CEF7; Fri, 3 Apr 2026 23:56:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775260597; bh=UTBAkQ9neJE5ofzAe8EoJOdScc3B7H+1wVjcdejfLXE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=msMw8XsxjRYu5Qo/LG2w1oxhFGH3qTNP+e6ZeC1dImikJ77b4ZXGx3XA9QhlqGJJ+ oit5I7F1Stpw2pTfs7XERpfiHyPfnX101tIhxe+WQMJU75tF4Oo4euZGlz4bS/Nu2P wDaZyuHnmi01s5cYi/fd5Z9e1ydGm8UEEItUV1JEHSRzy2Wpa86h9uq3su8UFFhuBq WyNz82GJf9XISqj2SlvCHfW9Qw6IBVr6XNoxUo9+kphoTQmklrWRLvo3oWL4lL2uH/ 0rPWE3+VjvZqL86WHUWkAUsM7TkYkwk9Es17NkNORQbmddQztVgSDSPlniDDv+aY0D bw+VdVawPdmRQ== Date: Fri, 3 Apr 2026 16:56:36 -0700 From: Jakub Kicinski To: Maciej Fijalkowski Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, magnus.karlsson@intel.com, stfomichev@gmail.com, pabeni@redhat.com, horms@kernel.org, larysa.zaremba@intel.com, aleksander.lobakin@intel.com, bjorn@kernel.org Subject: Re: [PATCH v6 net 3/8] xsk: fix XDP_UMEM_SG_FLAG issues Message-ID: <20260403165636.1f4ee958@kernel.org> In-Reply-To: <20260402154958.562179-4-maciej.fijalkowski@intel.com> References: <20260402154958.562179-1-maciej.fijalkowski@intel.com> <20260402154958.562179-4-maciej.fijalkowski@intel.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 2 Apr 2026 17:49:53 +0200 Maciej Fijalkowski wrote: > Currently xp_assign_dev_shared() is missing XDP_USE_SG being propagated > to flags so set it in order to preserve mtu check that is supposed to be > done only when no multi-buffer setup is in picture. > > Also, this flag has the same value as XDP_UMEM_TX_SW_CSUM so we could > get unexpected SG setups for software Tx checksums. Since csum flag is > UAPI, modify value of XDP_UMEM_SG_FLAG. should we maybe add: BUILD_BUG_ON(XDP_UMEM_SG_FLAG & XDP_UMEM_FLAGS_VALID) somewhere or use a hack like this ? #define XDP_UMEM_SG_FLAG (XDP_UMEM_FLAGS_VALID + 1) > diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h > index 23e8861e8b25..ebac60a3d8a1 100644 > --- a/include/net/xdp_sock.h > +++ b/include/net/xdp_sock.h > @@ -14,7 +14,7 @@ > #include > #include > > -#define XDP_UMEM_SG_FLAG (1 << 1) > +#define XDP_UMEM_SG_FLAG BIT(3) > > struct net_device; > struct xsk_queue; > diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c > index 37b7a68b89b3..729602a3cec0 100644 > --- a/net/xdp/xsk_buff_pool.c > +++ b/net/xdp/xsk_buff_pool.c > @@ -247,6 +247,10 @@ int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_sock *umem_xs, > struct xdp_umem *umem = umem_xs->umem; > > flags = umem->zc ? XDP_ZEROCOPY : XDP_COPY; > + > + if (umem->flags & XDP_UMEM_SG_FLAG) > + flags |= XDP_USE_SG; > + > if (umem_xs->pool->uses_need_wakeup) > flags |= XDP_USE_NEED_WAKEUP; >