diff options
Diffstat (limited to 'features/rt/xfrm-Use-sequence-counter-with-associated-spinlock.patch')
| -rw-r--r-- | features/rt/xfrm-Use-sequence-counter-with-associated-spinlock.patch | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/features/rt/xfrm-Use-sequence-counter-with-associated-spinlock.patch b/features/rt/xfrm-Use-sequence-counter-with-associated-spinlock.patch new file mode 100644 index 00000000..78fb2552 --- /dev/null +++ b/features/rt/xfrm-Use-sequence-counter-with-associated-spinlock.patch @@ -0,0 +1,65 @@ +From bdb062ede4003ee86bd6c2665b92856d69b14c6a Mon Sep 17 00:00:00 2001 +From: "Ahmed S. Darwish" <a.darwish@linutronix.de> +Date: Wed, 10 Jun 2020 12:53:22 +0200 +Subject: [PATCH 087/191] 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(-) + +diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c +index d01ca1a18418..14059a9051b8 100644 +--- a/net/xfrm/xfrm_state.c ++++ b/net/xfrm/xfrm_state.c +@@ -44,7 +44,7 @@ static void xfrm_state_gc_task(struct work_struct *work); + */ + + 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_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 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_spinlock_init(&xfrm_state_hash_generation, ++ &net->xfrm.xfrm_state_lock); + return 0; + + out_byspi: +-- +2.19.1 + |