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net: xfrm: Use sequence counter with associated spinlock

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A sequence counter write section must be serialized or its internal
state can get corrupted. A plain seqcount_t does not contain the
information of which lock must be held to guaranteee write side
serialization.

For xfrm_state_hash_generation, use seqcount_spinlock_t instead of plain
seqcount_t.  This allows to associate the spinlock used for write
serialization with the sequence counter. It thus enables lockdep to
verify that the write serialization lock is indeed held before entering
the sequence counter write section.

If lockdep is disabled, this lock association is compiled out and has
neither storage size nor runtime overhead.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Ahmed S. Darwish 2021-03-16 11:56:30 +01:00 committed by Steffen Klassert
parent e88add19f6
commit bc8e0adff3
2 changed files with 3 additions and 2 deletions
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2
include/net/netns/xfrm.h
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@ -73,7 +73,7 @@ struct netns_xfrm {
struct dst_ops xfrm6_dst_ops;
#endif
spinlock_t xfrm_state_lock;
seqcount_t xfrm_state_hash_generation;
seqcount_spinlock_t xfrm_state_hash_generation;
spinlock_t xfrm_policy_lock;
struct mutex xfrm_cfg_mutex;

3
net/xfrm/xfrm_state.c
View file

@ -2665,7 +2665,8 @@ int __net_init xfrm_state_init(struct net *net)
net->xfrm.state_num = 0;
INIT_WORK(&net->xfrm.state_hash_work, xfrm_hash_resize);
spin_lock_init(&net->xfrm.xfrm_state_lock);
seqcount_init(&net->xfrm.xfrm_state_hash_generation);
seqcount_spinlock_init(&net->xfrm.xfrm_state_hash_generation,
&net->xfrm.xfrm_state_lock);
return 0;
out_byspi: