mirror of
https://github.com/linuxkit/linuxkit.git
synced 2025-07-24 03:15:36 +00:00
60 lines
2.3 KiB
Diff
60 lines
2.3 KiB
Diff
From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
|
|
Date: Wed, 10 Jun 2020 12:53:22 +0200
|
|
Subject: [PATCH 24/24] xfrm: Use sequence counter with associated spinlock
|
|
|
|
A sequence counter write side critical section must be protected by some
|
|
form of locking to serialize writers. A plain seqcount_t does not
|
|
contain the information of which lock must be held when entering a write
|
|
side critical section.
|
|
|
|
Use the new seqcount_spinlock_t data type, which allows to associate a
|
|
spinlock with the sequence counter. This enables lockdep to verify that
|
|
the spinlock used for writer serialization is held when the write side
|
|
critical section is entered.
|
|
|
|
If lockdep is disabled this lock association is compiled out and has
|
|
neither storage size nor runtime overhead.
|
|
|
|
Upstream-status: The xfrm locking used for seqcoun writer serialization
|
|
appears to be broken. If that's the case, a proper fix will need to be
|
|
submitted upstream. (e.g. make the seqcount per network namespace?)
|
|
|
|
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
net/xfrm/xfrm_state.c | 9 ++++++++-
|
|
1 file changed, 8 insertions(+), 1 deletion(-)
|
|
|
|
--- a/net/xfrm/xfrm_state.c
|
|
+++ b/net/xfrm/xfrm_state.c
|
|
@@ -44,7 +44,7 @@ static void xfrm_state_gc_task(struct wo
|
|
*/
|
|
|
|
static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024;
|
|
-static __read_mostly seqcount_t xfrm_state_hash_generation = SEQCNT_ZERO(xfrm_state_hash_generation);
|
|
+static __read_mostly seqcount_spinlock_t xfrm_state_hash_generation;
|
|
static struct kmem_cache *xfrm_state_cache __ro_after_init;
|
|
|
|
static DECLARE_WORK(xfrm_state_gc_work, xfrm_state_gc_task);
|
|
@@ -139,6 +139,11 @@ static void xfrm_hash_resize(struct work
|
|
return;
|
|
}
|
|
|
|
+ /* XXX - the locking which protects the sequence counter appears
|
|
+ * to be broken here. The sequence counter is global, but the
|
|
+ * spinlock used for the sequence counter write serialization is
|
|
+ * per network namespace...
|
|
+ */
|
|
spin_lock_bh(&net->xfrm.xfrm_state_lock);
|
|
write_seqcount_begin(&xfrm_state_hash_generation);
|
|
|
|
@@ -2666,6 +2671,8 @@ int __net_init xfrm_state_init(struct ne
|
|
net->xfrm.state_num = 0;
|
|
INIT_WORK(&net->xfrm.state_hash_work, xfrm_hash_resize);
|
|
spin_lock_init(&net->xfrm.xfrm_state_lock);
|
|
+ seqcount_spinlock_init(&xfrm_state_hash_generation,
|
|
+ &net->xfrm.xfrm_state_lock);
|
|
return 0;
|
|
|
|
out_byspi:
|