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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A9782CD343F for ; Tue, 12 May 2026 20:32:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Tg4Djrl74YT/GwwzOrQUNp0R5Byl2aTJTljA89ekXv8=; b=eDAvyfplC5Swp6l96qQ0Vfhr3I 65ibP2Q169rG3ysZZR1gScBqVsRmIdTYHvwL3d6K25Y0umSgw0/y+dpfShvyEVuuG2muu/2/jy6do 8uKf/era88q7Pgg5Y0vBVBtNbayL4MEs564VrFNaOhpwggpqbdQx9Al2uzbdvU/KcgfdkE1g8teLA tyGoK+1X5qm70KbXNav+ho6peLuXBrMy9pPwFKSog9JIQNYn2/jov39xnqtpTnb+Igr0DF0NFmdXJ 4PBotjCoSgdx634hjKpGdoTNnT68mqBCRZDtNeqh9kCJ3Y/+N+wrZMYFtyGyoJZOjrYoPU9OAaFL9 05GY1mEw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMtlj-00000000LZ9-2zgx; Tue, 12 May 2026 20:31:55 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMtlg-00000000LYK-2pXI; Tue, 12 May 2026 20:31:54 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 8CEAE43459; Tue, 12 May 2026 20:31:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5BDEC2BCB0; Tue, 12 May 2026 20:31:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778617911; bh=V71zFNi7F3e+R7/dBjLOtPApPvnjD2YIfhm5M85nDfQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WCTu3Y1eda32Ya+9Wq+DNFrfDSFhyBHnhYZDkhrFzkDZzP8KhCBfb7GjDMmH1eqm9 c6Dyi97gHPT/Ok5rD6wRxsJfbe9+rscxhD8GuEhuqJijVV1YYB6vswuXoZ2jw3J8qc cKIOCosZ4diJV62XkJXa08orZaR7Bdi3QIzr2DXPRLVwZFAfHIbV7qlrapF1bzOrkK jVCY0rc7fwVjh5QbPhrQbcDtUqBZzAc/fP10rIadEsBf7cTxssxLd+Y2Dm7Gy/Uj50 s7+RzykdBuVc2WyE7YR2sd6ivAEikSnwwYiksX35yJNrdv39q7gEefCzhNnhbPxoML k07u/vEgagQBw== Date: Tue, 12 May 2026 22:31:48 +0200 From: Lorenzo Bianconi To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Christian Marangi , Benjamin Larsson , linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, netdev@vger.kernel.org, devicetree@vger.kernel.org, Xuegang Lu Subject: Re: [PATCH net-next v6 02/12] net: airoha: Reserve RX headroom to avoid skb reallocation Message-ID: References: <20260511-airoha-eth-multi-serdes-v6-0-c899462c4f75@kernel.org> <20260511-airoha-eth-multi-serdes-v6-2-c899462c4f75@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="TR0CKm29FXXTLKXr" Content-Disposition: inline In-Reply-To: <20260511-airoha-eth-multi-serdes-v6-2-c899462c4f75@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260512_133152_754886_540083C4 X-CRM114-Status: GOOD ( 18.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --TR0CKm29FXXTLKXr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On May 11, Lorenzo Bianconi wrote: > Reserve NET_SKB_PAD + NET_IP_ALIGN bytes of headroom for received packets > to avoid skb head reallocation when pushing protocol headers into the skb. >=20 > Tested-by: Xuegang Lu > Signed-off-by: Lorenzo Bianconi > --- > drivers/net/ethernet/airoha/airoha_eth.c | 12 ++++++++---- > drivers/net/ethernet/airoha/airoha_eth.h | 2 ++ > 2 files changed, 10 insertions(+), 4 deletions(-) >=20 > diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ether= net/airoha/airoha_eth.c > index f71fb18197ec..3fe2561c85f1 100644 > --- a/drivers/net/ethernet/airoha/airoha_eth.c > +++ b/drivers/net/ethernet/airoha/airoha_eth.c > @@ -543,9 +543,10 @@ static int airoha_qdma_fill_rx_queue(struct airoha_q= ueue *q) > q->queued++; > nframes++; > =20 > + offset +=3D AIROHA_RX_HEADROOM; > e->buf =3D page_address(page) + offset; > e->dma_addr =3D page_pool_get_dma_addr(page) + offset; > - e->dma_len =3D SKB_WITH_OVERHEAD(q->buf_size); > + e->dma_len =3D SKB_WITH_OVERHEAD(AIROHA_RX_LEN(q->buf_size)); > =20 > val =3D FIELD_PREP(QDMA_DESC_LEN_MASK, e->dma_len); > WRITE_ONCE(desc->ctrl, cpu_to_le32(val)); > @@ -616,8 +617,9 @@ static int airoha_qdma_rx_process(struct airoha_queue= *q, int budget) > =20 > page =3D virt_to_head_page(e->buf); > len =3D FIELD_GET(QDMA_DESC_LEN_MASK, desc_ctrl); > - data_len =3D q->skb ? q->buf_size > - : SKB_WITH_OVERHEAD(q->buf_size); > + data_len =3D q->skb > + ? AIROHA_RX_LEN(q->buf_size) > + : SKB_WITH_OVERHEAD(AIROHA_RX_LEN(q->buf_size)); > if (!len || data_len < len) > goto free_frag; > =20 > @@ -627,10 +629,12 @@ static int airoha_qdma_rx_process(struct airoha_que= ue *q, int budget) > =20 > port =3D eth->ports[p]; > if (!q->skb) { /* first buffer */ > - q->skb =3D napi_build_skb(e->buf, q->buf_size); > + q->skb =3D napi_build_skb(e->buf - AIROHA_RX_HEADROOM, > + q->buf_size); > if (!q->skb) > goto free_frag; > =20 > + skb_reserve(q->skb, AIROHA_RX_HEADROOM); > __skb_put(q->skb, len); > skb_mark_for_recycle(q->skb); > q->skb->dev =3D port->dev; > diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ether= net/airoha/airoha_eth.h > index 58530d096de7..d3781103abb5 100644 > --- a/drivers/net/ethernet/airoha/airoha_eth.h > +++ b/drivers/net/ethernet/airoha/airoha_eth.h > @@ -32,6 +32,8 @@ > #define AIROHA_FE_MC_MAX_VLAN_TABLE 64 > #define AIROHA_FE_MC_MAX_VLAN_PORT 16 > #define AIROHA_NUM_TX_IRQ 2 > +#define AIROHA_RX_HEADROOM (NET_SKB_PAD + NET_IP_ALIGN) > +#define AIROHA_RX_LEN(_n) ((_n) - AIROHA_RX_HEADROOM) > #define HW_DSCP_NUM 2048 > #define IRQ_QUEUE_LEN(_n) ((_n) ? 1024 : 2048) > #define TX_DSCP_NUM 1024 >=20 > --=20 > 2.54.0 >=20 commenting on sashiko's report: https://sashiko.dev/#/patchset/20260511-airoha-eth-multi-serdes-v6-0-c89946= 2c4f75%40kernel.org - Does the length passed to dma_sync_single_for_cpu() also need to be updat= ed to match the new DMA length? I will fix it in v7. Regards, Lorenzo --TR0CKm29FXXTLKXr Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCagOONAAKCRA6cBh0uS2t rKGaAQDJBFUqVKCNJOmGIhF2q0V3siWnJZZJ0yQN3UeaMOX2dQD/Ub3cCxWe1pCg P1grqoWgyEKmfQ6xFJ6PGy4FF1zA+AA= =57t/ -----END PGP SIGNATURE----- --TR0CKm29FXXTLKXr--