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From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: intel-wired-lan@lists.osuosl.org
Cc: "Alexander Lobakin" <alexandr.lobakin@intel.com>,
	"Jesse Brandeburg" <jesse.brandeburg@intel.com>,
	"Tony Nguyen" <anthony.l.nguyen@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Björn Töpel" <bjorn@kernel.org>,
	"Maciej Fijalkowski" <maciej.fijalkowski@intel.com>,
	"Michal Swiatkowski" <michal.swiatkowski@linux.intel.com>,
	"Jeff Kirsher" <jeffrey.t.kirsher@intel.com>,
	"Krzysztof Kazimierczak" <krzysztof.kazimierczak@intel.com>,
	"Jithu Joseph" <jithu.joseph@intel.com>,
	"Andre Guedes" <andre.guedes@intel.com>,
	"Vedang Patel" <vedang.patel@intel.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	bpf@vger.kernel.org
Subject: [PATCH v3 net-next 1/9] i40e: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb
Date: Tue,  7 Dec 2021 21:55:28 +0100	[thread overview]
Message-ID: <20211207205536.563550-2-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <20211207205536.563550-1-alexandr.lobakin@intel.com>

{__,}napi_alloc_skb() allocates and reserves additional NET_SKB_PAD
+ NET_IP_ALIGN for any skb.
OTOH, i40e_construct_skb_zc() currently allocates and reserves
additional `xdp->data - xdp->data_hard_start`, which is
XDP_PACKET_HEADROOM for XSK frames.
There's no need for that at all as the frame is post-XDP and will
go only to the networking stack core.
Pass the size of the actual data only to __napi_alloc_skb() and
don't reserve anything. This will give enough headroom for stack
processing.

Fixes: 0a714186d3c0 ("i40e: add AF_XDP zero-copy Rx support")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index f08d19b8c554..9564906b7da8 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -245,13 +245,11 @@ static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring,
 	struct sk_buff *skb;
 
 	/* allocate a skb to store the frags */
-	skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
-			       xdp->data_end - xdp->data_hard_start,
+	skb = __napi_alloc_skb(&rx_ring->q_vector->napi, datasize,
 			       GFP_ATOMIC | __GFP_NOWARN);
 	if (unlikely(!skb))
 		goto out;
 
-	skb_reserve(skb, xdp->data - xdp->data_hard_start);
 	memcpy(__skb_put(skb, datasize), xdp->data, datasize);
 	if (metasize)
 		skb_metadata_set(skb, metasize);
-- 
2.33.1


WARNING: multiple messages have this Message-ID (diff)
From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: intel-wired-lan@osuosl.org
Subject: [Intel-wired-lan] [PATCH v3 net-next 1/9] i40e: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb
Date: Tue,  7 Dec 2021 21:55:28 +0100	[thread overview]
Message-ID: <20211207205536.563550-2-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <20211207205536.563550-1-alexandr.lobakin@intel.com>

{__,}napi_alloc_skb() allocates and reserves additional NET_SKB_PAD
+ NET_IP_ALIGN for any skb.
OTOH, i40e_construct_skb_zc() currently allocates and reserves
additional `xdp->data - xdp->data_hard_start`, which is
XDP_PACKET_HEADROOM for XSK frames.
There's no need for that at all as the frame is post-XDP and will
go only to the networking stack core.
Pass the size of the actual data only to __napi_alloc_skb() and
don't reserve anything. This will give enough headroom for stack
processing.

Fixes: 0a714186d3c0 ("i40e: add AF_XDP zero-copy Rx support")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index f08d19b8c554..9564906b7da8 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -245,13 +245,11 @@ static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring,
 	struct sk_buff *skb;
 
 	/* allocate a skb to store the frags */
-	skb = __napi_alloc_skb(&rx_ring->q_vector->napi,
-			       xdp->data_end - xdp->data_hard_start,
+	skb = __napi_alloc_skb(&rx_ring->q_vector->napi, datasize,
 			       GFP_ATOMIC | __GFP_NOWARN);
 	if (unlikely(!skb))
 		goto out;
 
-	skb_reserve(skb, xdp->data - xdp->data_hard_start);
 	memcpy(__skb_put(skb, datasize), xdp->data, datasize);
 	if (metasize)
 		skb_metadata_set(skb, metasize);
-- 
2.33.1


  reply	other threads:[~2021-12-07 20:56 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-07 20:55 [PATCH v3 net-next 0/9] net: intel: napi_alloc_skb() vs metadata Alexander Lobakin
2021-12-07 20:55 ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` Alexander Lobakin [this message]
2021-12-07 20:55   ` [Intel-wired-lan] [PATCH v3 net-next 1/9] i40e: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 2/9] i40e: respect metadata " Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2022-01-10 10:31   ` Bhandare, KiranX
2022-01-10 10:31     ` Bhandare, KiranX
2021-12-07 20:55 ` [PATCH v3 net-next 3/9] ice: respect metadata in legacy-rx/ice_construct_skb() Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 4/9] ice: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 5/9] ice: respect metadata " Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 6/9] igc: don't reserve excessive XDP_PACKET_HEADROOM " Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 7/9] ixgbe: pass bi->xdp to ixgbe_construct_skb_zc() directly Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 8/9] ixgbe: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-07 20:55 ` [PATCH v3 net-next 9/9] i40e: respect metadata " Alexander Lobakin
2021-12-07 20:55   ` [Intel-wired-lan] " Alexander Lobakin
2021-12-08 13:47   ` Jesper Dangaard Brouer
2021-12-08 13:47     ` [Intel-wired-lan] " Jesper Dangaard Brouer

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