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 88D0636F913; Tue, 12 May 2026 20:31:51 +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=1778617911; cv=none; b=TgFj0GIOoTaVh6nSOf6AMjKF3AahtFo56J0UjRsxoAlVnW2GjbtcNtsP7r9XctAXC+dxIuSQe0Q3+hjk0Z+FP9k93DPZ/5Tu452l7+rrmAZM5oqwyiPHZ6IAEUa2Ig0ILyMCYlSFkCDoemUxtqKx82TD00z3xM8VzcrowFkY+RM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778617911; c=relaxed/simple; bh=V71zFNi7F3e+R7/dBjLOtPApPvnjD2YIfhm5M85nDfQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ed7s/Ye2xeb9fU9A5KhAeezj9UOYd94TTAnjYOVPHOX3WxE84B7+z3C8uTcDJlgqljbhrvVgFtySUjcs+N5bqlJbjRya+ixbrZO9p53NSWFlW1pCHGC0RuAsRSKm2VUnAUBqAB3vMiep+KoUDr7fAM9RJfKrGjhF+4s/KClFKrg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WCTu3Y1e; 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="WCTu3Y1e" 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> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> --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--