user/sven/linux.git/net/core/dev.h, branch v6.17.9

net: prevent deadlocks when enabling NAPIs with mixed kthread config

2025-08-12T12:43:05Z

The following order of calls currently deadlocks if: - device has threaded=1; and - NAPI has persistent config with threaded=0. netif_napi_add_weight_config() dev->threaded == 1 napi_kthread_create() napi_enable() napi_restore_config() napi_set_threaded(0) napi_stop_kthread() while (NAPIF_STATE_SCHED) msleep(20) We deadlock because disabled NAPI has STATE_SCHED set. Creating a thread in netif_napi_add() just to destroy it in napi_disable() is fairly ugly in the first place. Let's read both the device config and the NAPI config in netif_napi_add(). Fixes: e6d76268813d ("net: Update threaded state in napi config in netif_set_threaded") Signed-off-by: Jakub Kicinski Reviewed-by: Joe Damato Link: https://patch.msgid.link/20250809001205.1147153-4-kuba@kernel.org Signed-off-by: Paolo Abeni

net: define an enum for the napi threaded state

2025-07-25T01:34:55Z

Instead of using '0' and '1' for napi threaded state use an enum with 'disabled' and 'enabled' states. Tested: ./tools/testing/selftests/net/nl_netdev.py TAP version 13 1..7 ok 1 nl_netdev.empty_check ok 2 nl_netdev.lo_check ok 3 nl_netdev.page_pool_check ok 4 nl_netdev.napi_list_check ok 5 nl_netdev.dev_set_threaded ok 6 nl_netdev.napi_set_threaded ok 7 nl_netdev.nsim_rxq_reset_down # Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0 Signed-off-by: Samiullah Khawaja Link: https://patch.msgid.link/20250723013031.2911384-4-skhawaja@google.com Signed-off-by: Jakub Kicinski

net: Use netif_threaded_enable instead of netif_set_threaded in drivers

2025-07-25T01:34:55Z

Prepare for adding an enum type for NAPI threaded states by adding netif_threaded_enable API. De-export the existing netif_set_threaded API and only use it internally. Update existing drivers to use netif_threaded_enable instead of the de-exported netif_set_threaded. Note that dev_set_threaded used by mt76 debugfs file is unchanged. Signed-off-by: Samiullah Khawaja Link: https://patch.msgid.link/20250723013031.2911384-3-skhawaja@google.com Signed-off-by: Jakub Kicinski

Add support to set NAPI threaded for individual NAPI

2025-07-15T01:02:37Z

A net device has a threaded sysctl that can be used to enable threaded NAPI polling on all of the NAPI contexts under that device. Allow enabling threaded NAPI polling at individual NAPI level using netlink. Extend the netlink operation `napi-set` and allow setting the threaded attribute of a NAPI. This will enable the threaded polling on a NAPI context. Add a test in `nl_netdev.py` that verifies various cases of threaded NAPI being set at NAPI and at device level. Tested ./tools/testing/selftests/net/nl_netdev.py TAP version 13 1..7 ok 1 nl_netdev.empty_check ok 2 nl_netdev.lo_check ok 3 nl_netdev.page_pool_check ok 4 nl_netdev.napi_list_check ok 5 nl_netdev.dev_set_threaded ok 6 nl_netdev.napi_set_threaded ok 7 nl_netdev.nsim_rxq_reset_down # Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0 Signed-off-by: Samiullah Khawaja Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250710211203.3979655-1-skhawaja@google.com Signed-off-by: Jakub Kicinski

netdev: add "ops compat locking" helpers

2025-04-10T00:01:51Z

Add helpers to "lock a netdev in a backward-compatible way", which for ops-locked netdevs will mean take the instance lock. For drivers which haven't opted into the ops locking we'll take rtnl_lock. The scoped foreach is dropping and re-taking the lock for each device, even if prev and next are both under rtnl_lock. I hope that's fine since we expect that netdev nl to be mostly supported by modern drivers, and modern drivers should also opt into the instance locking. Note that these helpers are mostly needed for queue related state, because drivers modify queue config in their ops in a non-atomic way. Or differently put, queue changes don't have a clear-cut API like NAPI configuration. Any state that can should just use the instance lock directly, not the "compat" hacks. Reviewed-by: Joe Damato Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250408195956.412733-4-kuba@kernel.org Signed-off-by: Jakub Kicinski

net: avoid potential race between netdev_get_by_index_lock() and netns switch

2025-04-10T00:01:51Z

netdev_get_by_index_lock() performs following steps: rcu_lock(); dev = lookup(netns, ifindex); dev_get(dev); rcu_unlock(); [... lock & validate the dev ...] return dev Validation right now only checks if the device is registered but since the lookup is netns-aware we must also protect against the device switching netns right after we dropped the RCU lock. Otherwise the caller in netns1 may get a pointer to a device which has just switched to netns2. We can't hold the lock for the entire netns change process (because of the NETDEV_UNREGISTER notifier), and there's no existing marking to indicate that the netns is unlisted because of netns move, so add one. AFAIU none of the existing netdev_get_by_index_lock() callers can suffer from this problem (NAPI code double checks the netns membership and other callers are either under rtnl_lock or not ns-sensitive), so this patch does not have to be treated as a fix. Reviewed-by: Joe Damato Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250408195956.412733-2-kuba@kernel.org Signed-off-by: Jakub Kicinski

net: rps: remove kfree_rcu_mightsleep() use

2025-04-08T19:30:55Z

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: annotate data-races around (struct sd_flow_limit)->count

2025-04-08T19:30:55Z

softnet_seq_show() can read fl->count while another cpu updates this field from skb_flow_limit(). Make this field an 'unsigned int', as its only consumer only deals with 32 bit. Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250407163602.170356-3-edumazet@google.com Signed-off-by: Jakub Kicinski

net: rps: change skb_flow_limit() hash function

2025-04-08T19:30:55Z

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

Revert "net: replace dev_addr_sem with netdev instance lock"

2025-03-19T17:52:00Z

This reverts commit df43d8bf10316a7c3b1e47e3cc0057a54df4a5b8. Cc: Kohei Enju Reviewed-by: Kuniyuki Iwashima Fixes: df43d8bf1031 ("net: replace dev_addr_sem with netdev instance lock") Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250312190513.1252045-2-sdf@fomichev.me Tested-by: Lei Yang Signed-off-by: Paolo Abeni