kernel/linux.git/include/net/busy_poll.h, branch linux-6.5.y

net: Fix a data-race around sysctl_net_busy_poll.

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

While reading sysctl_net_busy_poll, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 060212928670 ("net: add low latency socket poll") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller

tcp: fix another uninit-value (sk_rx_queue_mapping)

2021-12-03T14:15:49+00:00

KMSAN is still not happy [1]. I missed that passive connections do not inherit their sk_rx_queue_mapping values from the request socket, but instead tcp_child_process() is calling sk_mark_napi_id(child, skb) We have many sk_mark_napi_id() callers, so I am providing a new helper, forcing the setting sk_rx_queue_mapping and sk_napi_id. Note that we had no KMSAN report for sk_napi_id because passive connections got a copy of this field from the listener. sk_rx_queue_mapping in the other hand is inside the sk_dontcopy_begin/sk_dontcopy_end so sk_clone_lock() leaves this field uninitialized. We might remove dead code populating req->sk_rx_queue_mapping in the future. [1] BUG: KMSAN: uninit-value in __sk_rx_queue_set include/net/sock.h:1924 [inline] BUG: KMSAN: uninit-value in sk_rx_queue_update include/net/sock.h:1938 [inline] BUG: KMSAN: uninit-value in sk_mark_napi_id include/net/busy_poll.h:136 [inline] BUG: KMSAN: uninit-value in tcp_child_process+0xb42/0x1050 net/ipv4/tcp_minisocks.c:833 __sk_rx_queue_set include/net/sock.h:1924 [inline] sk_rx_queue_update include/net/sock.h:1938 [inline] sk_mark_napi_id include/net/busy_poll.h:136 [inline] tcp_child_process+0xb42/0x1050 net/ipv4/tcp_minisocks.c:833 tcp_v4_rcv+0x3d83/0x4ed0 net/ipv4/tcp_ipv4.c:2066 ip_protocol_deliver_rcu+0x760/0x10b0 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_local_deliver+0x584/0x8c0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:460 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:551 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:601 [inline] ip_sublist_rcv+0x11fd/0x1520 net/ipv4/ip_input.c:609 ip_list_rcv+0x95f/0x9a0 net/ipv4/ip_input.c:644 __netif_receive_skb_list_ptype net/core/dev.c:5505 [inline] __netif_receive_skb_list_core+0xe34/0x1240 net/core/dev.c:5553 __netif_receive_skb_list+0x7fc/0x960 net/core/dev.c:5605 netif_receive_skb_list_internal+0x868/0xde0 net/core/dev.c:5696 gro_normal_list net/core/dev.c:5850 [inline] napi_complete_done+0x579/0xdd0 net/core/dev.c:6587 virtqueue_napi_complete drivers/net/virtio_net.c:339 [inline] virtnet_poll+0x17b6/0x2350 drivers/net/virtio_net.c:1557 __napi_poll+0x14e/0xbc0 net/core/dev.c:7020 napi_poll net/core/dev.c:7087 [inline] net_rx_action+0x824/0x1880 net/core/dev.c:7174 __do_softirq+0x1fe/0x7eb kernel/softirq.c:558 run_ksoftirqd+0x33/0x50 kernel/softirq.c:920 smpboot_thread_fn+0x616/0xbf0 kernel/smpboot.c:164 kthread+0x721/0x850 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 Uninit was created at: __alloc_pages+0xbc7/0x10a0 mm/page_alloc.c:5409 alloc_pages+0x8a5/0xb80 alloc_slab_page mm/slub.c:1810 [inline] allocate_slab+0x287/0x1c20 mm/slub.c:1947 new_slab mm/slub.c:2010 [inline] ___slab_alloc+0xbdf/0x1e90 mm/slub.c:3039 __slab_alloc mm/slub.c:3126 [inline] slab_alloc_node mm/slub.c:3217 [inline] slab_alloc mm/slub.c:3259 [inline] kmem_cache_alloc+0xbb3/0x11c0 mm/slub.c:3264 sk_prot_alloc+0xeb/0x570 net/core/sock.c:1914 sk_clone_lock+0xd6/0x1940 net/core/sock.c:2118 inet_csk_clone_lock+0x8d/0x6a0 net/ipv4/inet_connection_sock.c:956 tcp_create_openreq_child+0xb1/0x1ef0 net/ipv4/tcp_minisocks.c:453 tcp_v4_syn_recv_sock+0x268/0x2710 net/ipv4/tcp_ipv4.c:1563 tcp_check_req+0x207c/0x2a30 net/ipv4/tcp_minisocks.c:765 tcp_v4_rcv+0x36f5/0x4ed0 net/ipv4/tcp_ipv4.c:2047 ip_protocol_deliver_rcu+0x760/0x10b0 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_local_deliver+0x584/0x8c0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:460 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:551 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:601 [inline] ip_sublist_rcv+0x11fd/0x1520 net/ipv4/ip_input.c:609 ip_list_rcv+0x95f/0x9a0 net/ipv4/ip_input.c:644 __netif_receive_skb_list_ptype net/core/dev.c:5505 [inline] __netif_receive_skb_list_core+0xe34/0x1240 net/core/dev.c:5553 __netif_receive_skb_list+0x7fc/0x960 net/core/dev.c:5605 netif_receive_skb_list_internal+0x868/0xde0 net/core/dev.c:5696 gro_normal_list net/core/dev.c:5850 [inline] napi_complete_done+0x579/0xdd0 net/core/dev.c:6587 virtqueue_napi_complete drivers/net/virtio_net.c:339 [inline] virtnet_poll+0x17b6/0x2350 drivers/net/virtio_net.c:1557 __napi_poll+0x14e/0xbc0 net/core/dev.c:7020 napi_poll net/core/dev.c:7087 [inline] net_rx_action+0x824/0x1880 net/core/dev.c:7174 __do_softirq+0x1fe/0x7eb kernel/softirq.c:558 Fixes: 342159ee394d ("net: avoid dirtying sk->sk_rx_queue_mapping") Fixes: a37a0ee4d25c ("net: avoid uninit-value from tcp_conn_request") Signed-off-by: Eric Dumazet Reported-by: syzbot Tested-by: Alexander Potapenko Signed-off-by: David S. Miller

net: avoid uninit-value from tcp_conn_request

2021-12-02T03:15:54+00:00

A recent change triggers a KMSAN warning, because request sockets do not initialize @sk_rx_queue_mapping field. Add sk_rx_queue_update() helper to make our intent clear. BUG: KMSAN: uninit-value in sk_rx_queue_set include/net/sock.h:1922 [inline] BUG: KMSAN: uninit-value in tcp_conn_request+0x3bcc/0x4dc0 net/ipv4/tcp_input.c:6922 sk_rx_queue_set include/net/sock.h:1922 [inline] tcp_conn_request+0x3bcc/0x4dc0 net/ipv4/tcp_input.c:6922 tcp_v4_conn_request+0x218/0x2a0 net/ipv4/tcp_ipv4.c:1528 tcp_rcv_state_process+0x2c5/0x3290 net/ipv4/tcp_input.c:6406 tcp_v4_do_rcv+0xb4e/0x1330 net/ipv4/tcp_ipv4.c:1738 tcp_v4_rcv+0x468d/0x4ed0 net/ipv4/tcp_ipv4.c:2100 ip_protocol_deliver_rcu+0x760/0x10b0 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_local_deliver+0x584/0x8c0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:460 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:551 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:601 [inline] ip_sublist_rcv+0x11fd/0x1520 net/ipv4/ip_input.c:609 ip_list_rcv+0x95f/0x9a0 net/ipv4/ip_input.c:644 __netif_receive_skb_list_ptype net/core/dev.c:5505 [inline] __netif_receive_skb_list_core+0xe34/0x1240 net/core/dev.c:5553 __netif_receive_skb_list+0x7fc/0x960 net/core/dev.c:5605 netif_receive_skb_list_internal+0x868/0xde0 net/core/dev.c:5696 gro_normal_list net/core/dev.c:5850 [inline] napi_complete_done+0x579/0xdd0 net/core/dev.c:6587 virtqueue_napi_complete drivers/net/virtio_net.c:339 [inline] virtnet_poll+0x17b6/0x2350 drivers/net/virtio_net.c:1557 __napi_poll+0x14e/0xbc0 net/core/dev.c:7020 napi_poll net/core/dev.c:7087 [inline] net_rx_action+0x824/0x1880 net/core/dev.c:7174 __do_softirq+0x1fe/0x7eb kernel/softirq.c:558 invoke_softirq+0xa4/0x130 kernel/softirq.c:432 __irq_exit_rcu kernel/softirq.c:636 [inline] irq_exit_rcu+0x76/0x130 kernel/softirq.c:648 common_interrupt+0xb6/0xd0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 smap_restore arch/x86/include/asm/smap.h:67 [inline] get_shadow_origin_ptr mm/kmsan/instrumentation.c:31 [inline] __msan_metadata_ptr_for_load_1+0x28/0x30 mm/kmsan/instrumentation.c:63 tomoyo_check_acl+0x1b0/0x630 security/tomoyo/domain.c:173 tomoyo_path_permission security/tomoyo/file.c:586 [inline] tomoyo_check_open_permission+0x61f/0xe10 security/tomoyo/file.c:777 tomoyo_file_open+0x24f/0x2d0 security/tomoyo/tomoyo.c:311 security_file_open+0xb1/0x1f0 security/security.c:1635 do_dentry_open+0x4e4/0x1bf0 fs/open.c:809 vfs_open+0xaf/0xe0 fs/open.c:957 do_open fs/namei.c:3426 [inline] path_openat+0x52f1/0x5dd0 fs/namei.c:3559 do_filp_open+0x306/0x760 fs/namei.c:3586 do_sys_openat2+0x263/0x8f0 fs/open.c:1212 do_sys_open fs/open.c:1228 [inline] __do_sys_open fs/open.c:1236 [inline] __se_sys_open fs/open.c:1232 [inline] __x64_sys_open+0x314/0x380 fs/open.c:1232 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae Uninit was created at: __alloc_pages+0xbc7/0x10a0 mm/page_alloc.c:5409 alloc_pages+0x8a5/0xb80 alloc_slab_page mm/slub.c:1810 [inline] allocate_slab+0x287/0x1c20 mm/slub.c:1947 new_slab mm/slub.c:2010 [inline] ___slab_alloc+0xbdf/0x1e90 mm/slub.c:3039 __slab_alloc mm/slub.c:3126 [inline] slab_alloc_node mm/slub.c:3217 [inline] slab_alloc mm/slub.c:3259 [inline] kmem_cache_alloc+0xbb3/0x11c0 mm/slub.c:3264 reqsk_alloc include/net/request_sock.h:91 [inline] inet_reqsk_alloc+0xaf/0x8b0 net/ipv4/tcp_input.c:6712 tcp_conn_request+0x910/0x4dc0 net/ipv4/tcp_input.c:6852 tcp_v4_conn_request+0x218/0x2a0 net/ipv4/tcp_ipv4.c:1528 tcp_rcv_state_process+0x2c5/0x3290 net/ipv4/tcp_input.c:6406 tcp_v4_do_rcv+0xb4e/0x1330 net/ipv4/tcp_ipv4.c:1738 tcp_v4_rcv+0x468d/0x4ed0 net/ipv4/tcp_ipv4.c:2100 ip_protocol_deliver_rcu+0x760/0x10b0 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_local_deliver+0x584/0x8c0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:460 [inline] ip_sublist_rcv_finish net/ipv4/ip_input.c:551 [inline] ip_list_rcv_finish net/ipv4/ip_input.c:601 [inline] ip_sublist_rcv+0x11fd/0x1520 net/ipv4/ip_input.c:609 ip_list_rcv+0x95f/0x9a0 net/ipv4/ip_input.c:644 __netif_receive_skb_list_ptype net/core/dev.c:5505 [inline] __netif_receive_skb_list_core+0xe34/0x1240 net/core/dev.c:5553 __netif_receive_skb_list+0x7fc/0x960 net/core/dev.c:5605 netif_receive_skb_list_internal+0x868/0xde0 net/core/dev.c:5696 gro_normal_list net/core/dev.c:5850 [inline] napi_complete_done+0x579/0xdd0 net/core/dev.c:6587 virtqueue_napi_complete drivers/net/virtio_net.c:339 [inline] virtnet_poll+0x17b6/0x2350 drivers/net/virtio_net.c:1557 __napi_poll+0x14e/0xbc0 net/core/dev.c:7020 napi_poll net/core/dev.c:7087 [inline] net_rx_action+0x824/0x1880 net/core/dev.c:7174 __do_softirq+0x1fe/0x7eb kernel/softirq.c:558 Fixes: 342159ee394d ("net: avoid dirtying sk->sk_rx_queue_mapping") Signed-off-by: Eric Dumazet Reported-by: syzbot Link: https://lore.kernel.org/r/20211130182939.2584764-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski

net: avoid dirtying sk->sk_napi_id

2021-10-26T01:02:12+00:00

sk_napi_id is located in a cache line that can be kept read mostly. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Signed-off-by: Jakub Kicinski

net: annotate data race around sk_ll_usec

2021-07-01T18:23:50+00:00

sk_ll_usec is read locklessly from sk_can_busy_loop() while another thread can change its value in sock_setsockopt() This is correct but needs annotations. BUG: KCSAN: data-race in __skb_try_recv_datagram / sock_setsockopt write to 0xffff88814eb5f904 of 4 bytes by task 14011 on cpu 0: sock_setsockopt+0x1287/0x2090 net/core/sock.c:1175 __sys_setsockopt+0x14f/0x200 net/socket.c:2100 __do_sys_setsockopt net/socket.c:2115 [inline] __se_sys_setsockopt net/socket.c:2112 [inline] __x64_sys_setsockopt+0x62/0x70 net/socket.c:2112 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff88814eb5f904 of 4 bytes by task 14001 on cpu 1: sk_can_busy_loop include/net/busy_poll.h:41 [inline] __skb_try_recv_datagram+0x14f/0x320 net/core/datagram.c:273 unix_dgram_recvmsg+0x14c/0x870 net/unix/af_unix.c:2101 unix_seqpacket_recvmsg+0x5a/0x70 net/unix/af_unix.c:2067 ____sys_recvmsg+0x15d/0x310 include/linux/uio.h:244 ___sys_recvmsg net/socket.c:2598 [inline] do_recvmmsg+0x35c/0x9f0 net/socket.c:2692 __sys_recvmmsg net/socket.c:2771 [inline] __do_sys_recvmmsg net/socket.c:2794 [inline] __se_sys_recvmmsg net/socket.c:2787 [inline] __x64_sys_recvmmsg+0xcf/0x150 net/socket.c:2787 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x00000000 -> 0x00000101 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 14001 Comm: syz-executor.3 Not tainted 5.13.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller

net, xdp, xsk: fix __sk_mark_napi_id_once napi_id error

2020-12-01T14:51:19+00:00

Stephen reported the following build error for !CONFIG_NET_RX_BUSY_POLL built kernels: In file included from fs/select.c:32: include/net/busy_poll.h: In function 'sk_mark_napi_id_once': include/net/busy_poll.h:150:36: error: 'const struct sk_buff' has no member named 'napi_id' 150 | __sk_mark_napi_id_once_xdp(sk, skb->napi_id); | ^~ Fix it by wrapping a CONFIG_NET_RX_BUSY_POLL around the helpers. Fixes: b02e5a0ebb17 ("xsk: Propagate napi_id to XDP socket Rx path") Reported-by: Stephen Rothwell Signed-off-by: Stephen Rothwell Signed-off-by: Daniel Borkmann Cc: Björn Töpel Link: https://lore.kernel.org/linux-next/20201201190746.7d3357fb@canb.auug.org.au

xsk: Propagate napi_id to XDP socket Rx path

2020-11-30T23:09:25+00:00

Add napi_id to the xdp_rxq_info structure, and make sure the XDP socket pick up the napi_id in the Rx path. The napi_id is used to find the corresponding NAPI structure for socket busy polling. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Acked-by: Ilias Apalodimas Acked-by: Michael S. Tsirkin Acked-by: Tariq Toukan Link: https://lore.kernel.org/bpf/20201130185205.196029-7-bjorn.topel@gmail.com

net: Add SO_BUSY_POLL_BUDGET socket option

2020-11-30T23:09:25+00:00

This option lets a user set a per socket NAPI budget for busy-polling. If the options is not set, it will use the default of 8. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Kicinski Link: https://lore.kernel.org/bpf/20201130185205.196029-3-bjorn.topel@gmail.com

net: Introduce preferred busy-polling

2020-11-30T23:09:25+00:00

The existing busy-polling mode, enabled by the SO_BUSY_POLL socket option or system-wide using the /proc/sys/net/core/busy_read knob, is an opportunistic. That means that if the NAPI context is not scheduled, it will poll it. If, after busy-polling, the budget is exceeded the busy-polling logic will schedule the NAPI onto the regular softirq handling. One implication of the behavior above is that a busy/heavy loaded NAPI context will never enter/allow for busy-polling. Some applications prefer that most NAPI processing would be done by busy-polling. This series adds a new socket option, SO_PREFER_BUSY_POLL, that works in concert with the napi_defer_hard_irqs and gro_flush_timeout knobs. The napi_defer_hard_irqs and gro_flush_timeout knobs were introduced in commit 6f8b12d661d0 ("net: napi: add hard irqs deferral feature"), and allows for a user to defer interrupts to be enabled and instead schedule the NAPI context from a watchdog timer. When a user enables the SO_PREFER_BUSY_POLL, again with the other knobs enabled, and the NAPI context is being processed by a softirq, the softirq NAPI processing will exit early to allow the busy-polling to be performed. If the application stops performing busy-polling via a system call, the watchdog timer defined by gro_flush_timeout will timeout, and regular softirq handling will resume. In summary; Heavy traffic applications that prefer busy-polling over softirq processing should use this option. Example usage: $ echo 2 | sudo tee /sys/class/net/ens785f1/napi_defer_hard_irqs $ echo 200000 | sudo tee /sys/class/net/ens785f1/gro_flush_timeout Note that the timeout should be larger than the userspace processing window, otherwise the watchdog will timeout and fall back to regular softirq processing. Enable the SO_BUSY_POLL/SO_PREFER_BUSY_POLL options on your socket. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Kicinski Link: https://lore.kernel.org/bpf/20201130185205.196029-2-bjorn.topel@gmail.com

net: Avoid overwriting valid skb->napi_id

2020-06-21T00:30:59+00:00

This will be useful to allow busy poll for tunneled traffic. In case of busy poll for sessions over tunnels, the underlying physical device's queues need to be polled. Tunnels schedule NAPI either via netif_rx() for backlog queue or schedule the gro_cell_poll(). netif_rx() propagates the valid skb->napi_id to the socket. OTOH, gro_cell_poll() stamps the skb->napi_id again by calling skb_mark_napi_id() with the tunnel NAPI which is not a busy poll candidate. This was preventing tunneled traffic to use busy poll. A valid NAPI ID in the skb indicates it was already marked for busy poll by a NAPI driver and hence needs to be copied into the socket. Signed-off-by: Amritha Nambiar Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller