kernel/linux.git/net/core/sysctl_net_core.c, branch v6.18.21

net: remove RTNL use for /proc/sys/net/core/rps_default_mask

2025-07-08T01:42:12+00:00

Use a dedicated mutex instead. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250702061558.1585870-1-edumazet@google.com Signed-off-by: Jakub Kicinski

net: rps: remove kfree_rcu_mightsleep() use

2025-04-08T19:30:55+00:00

Add an rcu_head to sd_flow_limit and rps_sock_flow_table structs to use the more conventional and predictable k[v]free_rcu(). Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250407163602.170356-5-edumazet@google.com Signed-off-by: Jakub Kicinski

net: rps: change skb_flow_limit() hash function

2025-04-08T19:30:55+00:00

As explained in commit f3483c8e1da6 ("net: rfs: hash function change"), masking low order bits of skb_get_hash(skb) has low entropy. A NIC with 32 RX queues uses the 5 low order bits of rss key to select a queue. This means all packets landing to a given queue share the same 5 low order bits. Switch to hash_32() to reduce hash collisions. Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250407163602.170356-2-edumazet@google.com Signed-off-by: Jakub Kicinski

net: set the minimum for net_hotdata.netdev_budget_usecs

2025-02-22T00:27:54+00:00

Commit 7acf8a1e8a28 ("Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning") added a possibility to set net_hotdata.netdev_budget_usecs, but added no lower bound checking. Commit a4837980fd9f ("net: revert default NAPI poll timeout to 2 jiffies") made the *initial* value HZ-dependent, so the initial value is at least 2 jiffies even for lower HZ values (2 ms for 1000 Hz, 8ms for 250 Hz, 20 ms for 100 Hz). But a user still can set improper values by a sysctl. Set .extra1 (the lower bound) for net_hotdata.netdev_budget_usecs to the same value as in the latter commit. That is to 2 jiffies. Fixes: a4837980fd9f ("net: revert default NAPI poll timeout to 2 jiffies") Fixes: 7acf8a1e8a28 ("Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning") Signed-off-by: Jiri Slaby (SUSE) Cc: Dmitry Yakunin Cc: Konstantin Khlebnikov Link: https://patch.msgid.link/20250220110752.137639-1-jirislaby@kernel.org Signed-off-by: Jakub Kicinski

net: let net.core.dev_weight always be non-zero

2025-01-18T03:00:11+00:00

The following problem was encountered during stability test: (NULL net_device): NAPI poll function process_backlog+0x0/0x530 \ returned 1, exceeding its budget of 0. ------------[ cut here ]------------ list_add double add: new=ffff88905f746f48, prev=ffff88905f746f48, \ next=ffff88905f746e40. WARNING: CPU: 18 PID: 5462 at lib/list_debug.c:35 \ __list_add_valid_or_report+0xf3/0x130 CPU: 18 UID: 0 PID: 5462 Comm: ping Kdump: loaded Not tainted 6.13.0-rc7+ RIP: 0010:__list_add_valid_or_report+0xf3/0x130 Call Trace: ? __warn+0xcd/0x250 ? __list_add_valid_or_report+0xf3/0x130 enqueue_to_backlog+0x923/0x1070 netif_rx_internal+0x92/0x2b0 __netif_rx+0x15/0x170 loopback_xmit+0x2ef/0x450 dev_hard_start_xmit+0x103/0x490 __dev_queue_xmit+0xeac/0x1950 ip_finish_output2+0x6cc/0x1620 ip_output+0x161/0x270 ip_push_pending_frames+0x155/0x1a0 raw_sendmsg+0xe13/0x1550 __sys_sendto+0x3bf/0x4e0 __x64_sys_sendto+0xdc/0x1b0 do_syscall_64+0x5b/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e The reproduction command is as follows: sysctl -w net.core.dev_weight=0 ping 127.0.0.1 This is because when the napi's weight is set to 0, process_backlog() may return 0 and clear the NAPI_STATE_SCHED bit of napi->state, causing this napi to be re-polled in net_rx_action() until __do_softirq() times out. Since the NAPI_STATE_SCHED bit has been cleared, napi_schedule_rps() can be retriggered in enqueue_to_backlog(), causing this issue. Making the napi's weight always non-zero solves this problem. Triggering this issue requires system-wide admin (setting is not namespaced). Fixes: e38766054509 ("[NET]: Fix sysctl net.core.dev_weight") Fixes: 3d48b53fb2ae ("net: dev_weight: TX/RX orthogonality") Signed-off-by: Liu Jian Link: https://patch.msgid.link/20250116143053.4146855-1-liujian56@huawei.com Signed-off-by: Jakub Kicinski

net: sysctl: allow dump_cpumask to handle higher numbers of CPUs

2024-10-23T08:28:26+00:00

This fixes the output of rps_default_mask and flow_limit_cpu_bitmap when the CPU count is > 448, as it was truncated. The underlying values are actually stored correctly when writing to these sysctl but displaying them uses a fixed length temporary buffer in dump_cpumask. This buffer can be too small if the CPU count is > 448. Fix this by dynamically allocating the buffer in dump_cpumask, using a guesstimate of what we need. Signed-off-by: Antoine Tenart Reviewed-by: Simon Horman Signed-off-by: Paolo Abeni

net: sysctl: do not reserve an extra char in dump_cpumask temporary buffer

2024-10-23T08:28:19+00:00

When computing the length we'll be able to use out of the buffers, one char is removed from the temporary one to make room for a newline. It should be removed from the output buffer length too, but in reality this is not needed as the later call to scnprintf makes sure a null char is written at the end of the buffer which we override with the newline. Signed-off-by: Antoine Tenart Signed-off-by: Paolo Abeni

net: sysctl: remove always-true condition

2024-10-23T08:28:19+00:00

Before adding a new line at the end of the temporary buffer in dump_cpumask, a length check is performed to ensure there is space for it. len = min(sizeof(kbuf) - 1, *lenp); len = scnprintf(kbuf, len, ...); if (len < *lenp) kbuf[len++] = '\n'; Note that the check is currently logically wrong, the written length is compared against the output buffer, not the temporary one. However this has no consequence as this is always true, even if fixed: scnprintf includes a null char at the end of the buffer but the returned length do not include it and there is always space for overriding it with a newline. Remove the condition. Signed-off-by: Antoine Tenart Reviewed-by: Simon Horman Signed-off-by: Paolo Abeni

net-timestamp: namespacify the sysctl_tstamp_allow_data

2024-10-08T22:33:11+00:00

Let it be tuned in per netns by admins. Signed-off-by: Jason Xing Reviewed-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20241005222609.94980-1-kerneljasonxing@gmail.com Signed-off-by: Jakub Kicinski

sysctl: treewide: constify the ctl_table argument of proc_handlers

2024-07-24T18:59:29+00:00

const qualify the struct ctl_table argument in the proc_handler function signatures. This is a prerequisite to moving the static ctl_table structs into .rodata data which will ensure that proc_handler function pointers cannot be modified. This patch has been generated by the following coccinelle script: ``` virtual patch @r1@ identifier ctl, write, buffer, lenp, ppos; identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)"; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos); @r2@ identifier func, ctl, write, buffer, lenp, ppos; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos) { ... } @r3@ identifier func; @@ int func( - struct ctl_table * + const struct ctl_table * ,int , void *, size_t *, loff_t *); @r4@ identifier func, ctl; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int , void *, size_t *, loff_t *); @r5@ identifier func, write, buffer, lenp, ppos; @@ int func( - struct ctl_table * + const struct ctl_table * ,int write, void *buffer, size_t *lenp, loff_t *ppos); ``` * Code formatting was adjusted in xfs_sysctl.c to comply with code conventions. The xfs_stats_clear_proc_handler, xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where adjusted. * The ctl_table argument in proc_watchdog_common was const qualified. This is called from a proc_handler itself and is calling back into another proc_handler, making it necessary to change it as part of the proc_handler migration. Co-developed-by: Thomas Weißschuh Signed-off-by: Thomas Weißschuh Co-developed-by: Joel Granados Signed-off-by: Joel Granados