diff mbox series

[v1,2/2] net: xfrm: Use sequence counter with associated spinlock

Message ID 20210316105630.1020270-3-a.darwish@linutronix.de (mailing list archive)
State Awaiting Upstream
Delegated to: Netdev Maintainers
Headers show
Series net: xfrm: Use seqcount_spinlock_t | expand

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Commit Message

Ahmed S. Darwish March 16, 2021, 10:56 a.m. UTC
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>
---
 include/net/netns/xfrm.h | 2 +-
 net/xfrm/xfrm_state.c    | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index b59d73d529ba..e816b6a3ef2b 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -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;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index ffd315cff984..4496f7efa220 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -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;
 
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