diff mbox series

[v4,net-next,4/9] ice: don't reserve excessive XDP_PACKET_HEADROOM on XSK Rx to skb

Message ID 20211208140702.642741-5-alexandr.lobakin@intel.com (mailing list archive)
State Awaiting Upstream
Delegated to: Netdev Maintainers
Headers show
Series net: intel: napi_alloc_skb() vs metadata | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers fail 1 blamed authors not CCed: krzysztof.kazimierczak@intel.com; 1 maintainers not CCed: krzysztof.kazimierczak@intel.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Alexander Lobakin Dec. 8, 2021, 2:06 p.m. UTC
{__,}napi_alloc_skb() allocates and reserves additional NET_SKB_PAD
+ NET_IP_ALIGN for any skb.
OTOH, ice_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: 2d4238f55697 ("ice: Add support for AF_XDP")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
---
 drivers/net/ethernet/intel/ice/ice_xsk.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Comments

Bhandare, KiranX Jan. 10, 2022, 10:13 a.m. UTC | #1
> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
> Alexander Lobakin
> Sent: Wednesday, December 8, 2021 7:37 PM
> To: intel-wired-lan@lists.osuosl.org
> Cc: Song Liu <songliubraving@fb.com>; Jesper Dangaard Brouer
> <hawk@kernel.org>; Daniel Borkmann <daniel@iogearbox.net>; Yonghong
> Song <yhs@fb.com>; Martin KaFai Lau <kafai@fb.com>; John Fastabend
> <john.fastabend@gmail.com>; Alexei Starovoitov <ast@kernel.org>; Andrii
> Nakryiko <andrii@kernel.org>; Björn Töpel <bjorn@kernel.org>;
> netdev@vger.kernel.org; Jakub Kicinski <kuba@kernel.org>; KP Singh
> <kpsingh@kernel.org>; bpf@vger.kernel.org; David S. Miller
> <davem@davemloft.net>; linux-kernel@vger.kernel.org
> Subject: [Intel-wired-lan] [PATCH v4 net-next 4/9] ice: don't reserve excessive
> XDP_PACKET_HEADROOM on XSK Rx to skb
> 
> {__,}napi_alloc_skb() allocates and reserves additional NET_SKB_PAD
> + NET_IP_ALIGN for any skb.
> OTOH, ice_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: 2d4238f55697 ("ice: Add support for AF_XDP")
> Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
> ---
>  drivers/net/ethernet/intel/ice/ice_xsk.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 

Tested-by: Kiran Bhandare <kiranx.bhandare@intel.com>  A Contingent Worker at Intel
diff mbox series

Patch

diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index f8ea6b0633eb..f0bd8e1953bf 100644
--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
@@ -430,15 +430,13 @@  ice_construct_skb_zc(struct ice_rx_ring *rx_ring, struct xdp_buff **xdp_arr)
 	struct xdp_buff *xdp = *xdp_arr;
 	unsigned int metasize = xdp->data - xdp->data_meta;
 	unsigned int datasize = xdp->data_end - xdp->data;
-	unsigned int datasize_hard = xdp->data_end - xdp->data_hard_start;
 	struct sk_buff *skb;
 
-	skb = __napi_alloc_skb(&rx_ring->q_vector->napi, datasize_hard,
+	skb = __napi_alloc_skb(&rx_ring->q_vector->napi, datasize,
 			       GFP_ATOMIC | __GFP_NOWARN);
 	if (unlikely(!skb))
 		return NULL;
 
-	skb_reserve(skb, xdp->data - xdp->data_hard_start);
 	memcpy(__skb_put(skb, datasize), xdp->data, datasize);
 	if (metasize)
 		skb_metadata_set(skb, metasize);