kernel/linux.git/include/linux/netdevice_xmit.h, branch v6.12.93

net/sched: act_mirred: add loop detection

2026-06-09T10:25:42+00:00

[ Upstream commit fe946a751d9b52b7c45ca34899723b314b79b249 ] Commit 0f022d32c3ec ("net/sched: Fix mirred deadlock on device recursion") added code in the fast path, even when act_mirred is not used. Prepare its revert by implementing loop detection in act_mirred. Adds an array of device pointers in struct netdev_xmit. tcf_mirred_is_act_redirect() can detect if the array already contains the target device. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Reviewed-by: Toke Høiland-Jørgensen Tested-by: Jamal Hadi Salim Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20251014171907.3554413-4-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: e80ad525fc7e ("net/sched: act_mirred: Fix return code in early mirred redirect error paths") Signed-off-by: Sasha Levin

net/sched: act_mirred: Move the recursion counter struct netdev_xmit

2026-06-09T10:25:42+00:00

[ Upstream commit 7fe70c06a182a140be9996b02256d907e114479a ] mirred_nest_level is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Move mirred_nest_level to struct netdev_xmit as u8, provide wrappers. Cc: Jamal Hadi Salim Cc: Cong Wang Cc: Jiri Pirko Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Juri Lelli Link: https://patch.msgid.link/20250512092736.229935-11-bigeasy@linutronix.de Signed-off-by: Paolo Abeni Stable-dep-of: e80ad525fc7e ("net/sched: act_mirred: Fix return code in early mirred redirect error paths") Signed-off-by: Sasha Levin

net: softnet_data: Make xmit per task.

2024-06-24T23:41:23+00:00

Softirq is preemptible on PREEMPT_RT. Without a per-CPU lock in local_bh_disable() there is no guarantee that only one device is transmitting at a time. With preemption and multiple senders it is possible that the per-CPU `recursion' counter gets incremented by different threads and exceeds XMIT_RECURSION_LIMIT leading to a false positive recursion alert. The `more' member is subject to similar problems if set by one thread for one driver and wrongly used by another driver within another thread. Instead of adding a lock to protect the per-CPU variable it is simpler to make xmit per-task. Sending and receiving skbs happens always in thread context anyway. Having a lock to protected the per-CPU counter would block/ serialize two sending threads needlessly. It would also require a recursive lock to ensure that the owner can increment the counter further. Make the softnet_data.xmit a task_struct member on PREEMPT_RT. Add needed wrapper. Cc: Ben Segall Cc: Daniel Bristot de Oliveira Cc: Dietmar Eggemann Cc: Juri Lelli Cc: Mel Gorman Cc: Steven Rostedt Cc: Valentin Schneider Cc: Vincent Guittot Signed-off-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20240620132727.660738-9-bigeasy@linutronix.de Signed-off-by: Jakub Kicinski