kernel/linux.git/include/net/gro.h, branch v6.6.131

net: allow small head cache usage with large MAX_SKB_FRAGS values

2025-11-24T09:30:05+00:00

[ Upstream commit 14ad6ed30a10afbe91b0749d6378285f4225d482 ] Sabrina reported the following splat: WARNING: CPU: 0 PID: 1 at net/core/dev.c:6935 netif_napi_add_weight_locked+0x8f2/0xba0 Modules linked in: CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc1-net-00092-g011b03359038 #996 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 RIP: 0010:netif_napi_add_weight_locked+0x8f2/0xba0 Code: e8 c3 e6 6a fe 48 83 c4 28 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc c7 44 24 10 ff ff ff ff e9 8f fb ff ff e8 9e e6 6a fe <0f> 0b e9 d3 fe ff ff e8 92 e6 6a fe 48 8b 04 24 be ff ff ff ff 48 RSP: 0000:ffffc9000001fc60 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88806ce48128 RCX: 1ffff11001664b9e RDX: ffff888008f00040 RSI: ffffffff8317ca42 RDI: ffff88800b325cb6 RBP: ffff88800b325c40 R08: 0000000000000001 R09: ffffed100167502c R10: ffff88800b3a8163 R11: 0000000000000000 R12: ffff88800ac1c168 R13: ffff88800ac1c168 R14: ffff88800ac1c168 R15: 0000000000000007 FS: 0000000000000000(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888008201000 CR3: 0000000004c94001 CR4: 0000000000370ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: gro_cells_init+0x1ba/0x270 xfrm_input_init+0x4b/0x2a0 xfrm_init+0x38/0x50 ip_rt_init+0x2d7/0x350 ip_init+0xf/0x20 inet_init+0x406/0x590 do_one_initcall+0x9d/0x2e0 do_initcalls+0x23b/0x280 kernel_init_freeable+0x445/0x490 kernel_init+0x20/0x1d0 ret_from_fork+0x46/0x80 ret_from_fork_asm+0x1a/0x30 irq event stamp: 584330 hardirqs last enabled at (584338): [] __up_console_sem+0x77/0xb0 hardirqs last disabled at (584345): [] __up_console_sem+0x5c/0xb0 softirqs last enabled at (583242): [] netlink_insert+0x14d/0x470 softirqs last disabled at (583754): [] netif_napi_add_weight_locked+0x77d/0xba0 on kernel built with MAX_SKB_FRAGS=45, where SKB_WITH_OVERHEAD(1024) is smaller than GRO_MAX_HEAD. Such built additionally contains the revert of the single page frag cache so that napi_get_frags() ends up using the page frag allocator, triggering the splat. Note that the underlying issue is independent from the mentioned revert; address it ensuring that the small head cache will fit either TCP and GRO allocation and updating napi_alloc_skb() and __netdev_alloc_skb() to select kmalloc() usage for any allocation fitting such cache. Reported-by: Sabrina Dubroca Suggested-by: Eric Dumazet Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS") Reviewed-by: Eric Dumazet Signed-off-by: Paolo Abeni [ Minor context change fixed. ] Signed-off-by: Wenshan Lan Signed-off-by: Sasha Levin

net: gro: fix udp bad offset in socket lookup by adding {inner_}network_offset to napi_gro_cb

2024-05-17T10:02:07+00:00

[ Upstream commit 5ef31ea5d053a8f493a772ebad3f3ce82c35d845 ] Commits a602456 ("udp: Add GRO functions to UDP socket") and 57c67ff ("udp: additional GRO support") introduce incorrect usage of {ip,ipv6}_hdr in the complete phase of gro. The functions always return skb->network_header, which in the case of encapsulated packets at the gro complete phase, is always set to the innermost L3 of the packet. That means that calling {ip,ipv6}_hdr for skbs which completed the GRO receive phase (both in gro_list and *_gro_complete) when parsing an encapsulated packet's _outer_ L3/L4 may return an unexpected value. This incorrect usage leads to a bug in GRO's UDP socket lookup. udp{4,6}_lib_lookup_skb functions use ip_hdr/ipv6_hdr respectively. These *_hdr functions return network_header which will point to the innermost L3, resulting in the wrong offset being used in __udp{4,6}_lib_lookup with encapsulated packets. This patch adds network_offset and inner_network_offset to napi_gro_cb, and makes sure both are set correctly. To fix the issue, network_offsets union is used inside napi_gro_cb, in which both the outer and the inner network offsets are saved. Reproduction example: Endpoint configuration example (fou + local address bind) # ip fou add port 6666 ipproto 4 # ip link add name tun1 type ipip remote 2.2.2.1 local 2.2.2.2 encap fou encap-dport 5555 encap-sport 6666 mode ipip # ip link set tun1 up # ip a add 1.1.1.2/24 dev tun1 Netperf TCP_STREAM result on net-next before patch is applied: net-next main, GRO enabled: $ netperf -H 1.1.1.2 -t TCP_STREAM -l 5 Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 131072 16384 16384 5.28 2.37 net-next main, GRO disabled: $ netperf -H 1.1.1.2 -t TCP_STREAM -l 5 Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 131072 16384 16384 5.01 2745.06 patch applied, GRO enabled: $ netperf -H 1.1.1.2 -t TCP_STREAM -l 5 Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 131072 16384 16384 5.01 2877.38 Fixes: a6024562ffd7 ("udp: Add GRO functions to UDP socket") Signed-off-by: Richard Gobert Reviewed-by: Eric Dumazet Reviewed-by: Willem de Bruijn Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: gro: fix misuse of CB in udp socket lookup

2023-07-29T16:10:27+00:00

This patch fixes a misuse of IP{6}CB(skb) in GRO, while calling to `udp6_lib_lookup2` when handling udp tunnels. `udp6_lib_lookup2` fetch the device from CB. The fix changes it to fetch the device from `skb->dev`. l3mdev case requires special attention since it has a master and a slave device. Fixes: a6024562ffd7 ("udp: Add GRO functions to UDP socket") Reported-by: Gal Pressman Signed-off-by: Richard Gobert Reviewed-by: David Ahern Signed-off-by: David S. Miller

net: move gso declarations and functions to their own files

2023-06-10T07:11:41+00:00

Move declarations into include/net/gso.h and code into net/core/gso.c Signed-off-by: Eric Dumazet Cc: Stanislav Fomichev Reviewed-by: Simon Horman Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230608191738.3947077-1-edumazet@google.com Signed-off-by: Jakub Kicinski

gro: decrease size of CB

2023-06-06T09:12:20+00:00

The GRO control block (NAPI_GRO_CB) is currently at its maximum size. This commit reduces its size by putting two groups of fields that are used only at different times into a union. Specifically, the fields frag0 and frag0_len are the fields that make up the frag0 optimisation mechanism, which is used during the initial parsing of the SKB. The fields last and age are used after the initial parsing, while the SKB is stored in the GRO list, waiting for other packets to arrive. There was one location in dev_gro_receive that modified the frag0 fields after setting last and age. I changed this accordingly without altering the code behaviour. Signed-off-by: Richard Gobert Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20230601161407.GA9253@debian Signed-off-by: Paolo Abeni

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2022-08-25T23:07:42+00:00

drivers/net/ethernet/mellanox/mlx5/core/en_fs.c 21234e3a84c7 ("net/mlx5e: Fix use after free in mlx5e_fs_init()") c7eafc5ed068 ("net/mlx5e: Convert ethtool_steering member of flow_steering struct to pointer") https://lore.kernel.org/all/20220825104410.67d4709c@canb.auug.org.au/ https://lore.kernel.org/all/20220823055533.334471-1-saeed@kernel.org/ Signed-off-by: Jakub Kicinski

net: gro: skb_gro_header helper function

2022-08-25T08:33:21+00:00

Introduce a simple helper function to replace a common pattern. When accessing the GRO header, we fetch the pointer from frag0, then test its validity and fetch it from the skb when necessary. This leads to the pattern skb_gro_header_fast -> skb_gro_header_hard -> skb_gro_header_slow recurring many times throughout GRO code. This patch replaces these patterns with a single inlined function call, improving code readability. Signed-off-by: Richard Gobert Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20220823071034.GA56142@debian Signed-off-by: Paolo Abeni

net: Fix a data-race around gro_normal_batch.

2022-08-24T12:46:58+00:00

While reading gro_normal_batch, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 323ebb61e32b ("net: use listified RX for handling GRO_NORMAL skbs") Signed-off-by: Kuniyuki Iwashima Acked-by: Edward Cree Signed-off-by: David S. Miller

net: gro: Fix a 'directive in macro's argument list' sparse warning

2022-02-18T11:00:25+00:00

Following the cited commit, sparse started complaining about: ../include/net/gro.h:58:1: warning: directive in macro's argument list ../include/net/gro.h:59:1: warning: directive in macro's argument list Fix that by moving the defines out of the struct_group() macro. Fixes: de5a1f3ce4c8 ("net: gro: minor optimization for dev_gro_receive()") Reviewed-by: Maxim Mikityanskiy Signed-off-by: Gal Pressman Acked-by: Alexander Lobakin Acked-by: Paolo Abeni Signed-off-by: David S. Miller

net: gro: minor optimization for dev_gro_receive()

2022-02-05T15:13:52+00:00

While inspecting some perf report, I noticed that the compiler emits suboptimal code for the napi CB initialization, fetching and storing multiple times the memory for flags bitfield. This is with gcc 10.3.1, but I observed the same with older compiler versions. We can help the compiler to do a nicer work clearing several fields at once using an u32 alias. The generated code is quite smaller, with the same number of conditional. Before: objdump -t net/core/gro.o | grep " F .text" 0000000000000bb0 l F .text 0000000000000357 dev_gro_receive After: 0000000000000bb0 l F .text 000000000000033c dev_gro_receive v1 -> v2: - use struct_group (Alexander and Alex) RFC -> v1: - use __struct_group to delimit the zeroed area (Alexander) Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller