kernel/linux.git/include/net/dst.h, branch v6.19.11

net: dst: introduce dst->dev_rcu

2025-08-30T02:36:31+00:00

Followup of commit 88fe14253e18 ("net: dst: add four helpers to annotate data-races around dst->dev"). We want to gradually add explicit RCU protection to dst->dev, including lockdep support. Add an union to alias dst->dev_rcu and dst->dev. Add dst_dev_net_rcu() helper. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-2-edumazet@google.com Signed-off-by: Jakub Kicinski

net: Add locking to protect skb->dev access in ip_output

2025-08-01T22:17:52+00:00

In ip_output() skb->dev is updated from the skb_dst(skb)->dev this can become invalid when the interface is unregistered and freed, Introduced new skb_dst_dev_rcu() function to be used instead of skb_dst_dev() within rcu_locks in ip_output.This will ensure that all the skb's associated with the dev being deregistered will be transnmitted out first, before freeing the dev. Given that ip_output() is called within an rcu_read_lock() critical section or from a bottom-half context, it is safe to introduce an RCU read-side critical section within it. Multiple panic call stacks were observed when UL traffic was run in concurrency with device deregistration from different functions, pasting one sample for reference. [496733.627565][T13385] Call trace: [496733.627570][T13385] bpf_prog_ce7c9180c3b128ea_cgroupskb_egres+0x24c/0x7f0 [496733.627581][T13385] __cgroup_bpf_run_filter_skb+0x128/0x498 [496733.627595][T13385] ip_finish_output+0xa4/0xf4 [496733.627605][T13385] ip_output+0x100/0x1a0 [496733.627613][T13385] ip_send_skb+0x68/0x100 [496733.627618][T13385] udp_send_skb+0x1c4/0x384 [496733.627625][T13385] udp_sendmsg+0x7b0/0x898 [496733.627631][T13385] inet_sendmsg+0x5c/0x7c [496733.627639][T13385] __sys_sendto+0x174/0x1e4 [496733.627647][T13385] __arm64_sys_sendto+0x28/0x3c [496733.627653][T13385] invoke_syscall+0x58/0x11c [496733.627662][T13385] el0_svc_common+0x88/0xf4 [496733.627669][T13385] do_el0_svc+0x2c/0xb0 [496733.627676][T13385] el0_svc+0x2c/0xa4 [496733.627683][T13385] el0t_64_sync_handler+0x68/0xb4 [496733.627689][T13385] el0t_64_sync+0x1a4/0x1a8 Changes in v3: - Replaced WARN_ON() with WARN_ON_ONCE(), as suggested by Willem de Bruijn. - Dropped legacy lines mistakenly pulled in from an outdated branch. Changes in v2: - Addressed review comments from Eric Dumazet - Used READ_ONCE() to prevent potential load/store tearing - Added skb_dst_dev_rcu() and used along with rcu_read_lock() in ip_output Signed-off-by: Sharath Chandra Vurukala Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250730105118.GA26100@hu-sharathv-hyd.qualcomm.com Signed-off-by: Jakub Kicinski

net: dst: add four helpers to annotate data-races around dst->dev

2025-07-02T21:32:30+00:00

dst->dev is read locklessly in many contexts, and written in dst_dev_put(). Fixing all the races is going to need many changes. We probably will have to add full RCU protection. Add three helpers to ease this painful process. static inline struct net_device *dst_dev(const struct dst_entry *dst) { return READ_ONCE(dst->dev); } static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) { return dst_dev(skb_dst(skb)); } static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) { return dev_net(skb_dst_dev(skb)); } static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb) { return dev_net_rcu(skb_dst_dev(skb)); } Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-7-edumazet@google.com Signed-off-by: Jakub Kicinski

net: dst: annotate data-races around dst->output

2025-07-02T21:32:30+00:00

dst_dev_put() can overwrite dst->output while other cpus might read this field (for instance from dst_output()) Add READ_ONCE()/WRITE_ONCE() annotations to suppress potential issues. We will likely need RCU protection in the future. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-6-edumazet@google.com Signed-off-by: Jakub Kicinski

net: dst: annotate data-races around dst->input

2025-07-02T21:32:29+00:00

dst_dev_put() can overwrite dst->input while other cpus might read this field (for instance from dst_input()) Add READ_ONCE()/WRITE_ONCE() annotations to suppress potential issues. We will likely need full RCU protection later. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-5-edumazet@google.com Signed-off-by: Jakub Kicinski

net: dst: annotate data-races around dst->lastuse

2025-07-02T21:32:29+00:00

(dst_entry)->lastuse is read and written locklessly, add corresponding annotations. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-4-edumazet@google.com Signed-off-by: Jakub Kicinski

net: dst: annotate data-races around dst->expires

2025-07-02T21:32:29+00:00

(dst_entry)->expires is read and written locklessly, add corresponding annotations. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-3-edumazet@google.com Signed-off-by: Jakub Kicinski

net: dst: annotate data-races around dst->obsolete

2025-07-02T21:32:29+00:00

(dst_entry)->obsolete is read locklessly, add corresponding annotations. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-2-edumazet@google.com Signed-off-by: Jakub Kicinski

net: reformat kdoc return statements

2024-12-09T22:44:59+00:00

kernel-doc -Wall warns about missing Return: statement for non-void functions. We have a number of kdocs in our headers which are missing the colon, IOW they use * Return some value or * Returns some value Having the colon makes some sense, it should help kdoc parser avoid false positives. So add them. This is mostly done with a sed script, and removing the unnecessary cases (mostly the comments which aren't kdoc). Acked-by: Johannes Berg Acked-by: Richard Cochran Acked-by: Sergey Ryazanov Reviewed-by: Edward Cree Acked-by: Alexandra Winter Acked-by: Pablo Neira Ayuso Link: https://patch.msgid.link/20241205165914.1071102-1-kuba@kernel.org Signed-off-by: Jakub Kicinski

include: net: add static inline dst_dev_overhead() to dst.h

2024-12-05T10:15:56+00:00

Add static inline dst_dev_overhead() function to include/net/dst.h. This helper function is used by ioam6_iptunnel, rpl_iptunnel and seg6_iptunnel to get the dev's overhead based on a cache entry (dst_entry). If the cache is empty, the default and generic value skb->mac_len is returned. Otherwise, LL_RESERVED_SPACE() over dst's dev is returned. Signed-off-by: Justin Iurman Cc: Alexander Lobakin Cc: Vadim Fedorenko Signed-off-by: Paolo Abeni