kernel/linux.git/include/linux/netdevice_xmit.h, branch v6.18.21Linux kernel stable tree (mirror)https://git.radix-linux.su/kernel/linux.git/atom?h=v6.18.212025-05-23T11:57:12+00:00netfilter: nf_dup_netdev: Move the recursion counter struct netdev_xmit2025-05-23T11:57:12+00:00Sebastian Andrzej Siewiorbigeasy@linutronix.de2025-05-12T10:28:46+00:00urn:sha1:f37ad91270397a6d053e8623bdb3cf79859691d2
nf_dup_skb_recursion 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 nf_dup_skb_recursion to struct netdev_xmit, provide wrappers.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
net/sched: act_mirred: Move the recursion counter struct netdev_xmit2025-05-15T13:23:31+00:00Sebastian Andrzej Siewiorbigeasy@linutronix.de2025-05-12T09:27:31+00:00urn:sha1:7fe70c06a182a140be9996b02256d907e114479a
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 <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20250512092736.229935-11-bigeasy@linutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net: softnet_data: Make xmit per task.2024-06-24T23:41:23+00:00Sebastian Andrzej Siewiorbigeasy@linutronix.de2024-06-20T13:21:58+00:00urn:sha1:ecefbc09e8ee768ae85b7bb7a1de8c8287397d68
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 <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-9-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>