netfilter: nf_dup{4, 6}: Move duplication check to task_struct

nf_skb_duplicated 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.

Due to the recursion involved, the simplest change is to make it a
per-task variable.

Move the per-CPU variable nf_skb_duplicated to task_struct and name it
in_nf_duplicate. Add it to the existing bitfield so it doesn't use
additional memory.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f96ac1982893..52d9c52dc8f2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1044,6 +1044,7 @@ struct task_struct {
 	/* delay due to memory thrashing */
 	unsigned                        in_thrashing:1;
 #endif
+	unsigned			in_nf_duplicate:1;
 #ifdef CONFIG_PREEMPT_RT
 	struct netdev_xmit		net_xmit;
 #endif