ChangeSet 1.1539.1.5, 2005/02/05 17:09:11-08:00, [EMAIL PROTECTED]
[NET]: Add barriers for dst refcnt.
In light of the recent discussion about sk_buff, I think we need
the following patch for dst_entry. This adds a memory barrier
before dst_release drops the refcnt, and a read memory barrier
before dst_destroy starts destroying the entry.
Signed-off-by: Herbert Xu <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
include/net/dst.h | 4 +++-
net/core/dst.c | 9 +++++++--
2 files changed, 10 insertions(+), 3 deletions(-)
diff -Nru a/include/net/dst.h b/include/net/dst.h
--- a/include/net/dst.h 2005-02-09 09:06:27 -08:00
+++ b/include/net/dst.h 2005-02-09 09:06:27 -08:00
@@ -104,8 +104,10 @@
static inline
void dst_release(struct dst_entry * dst)
{
- if (dst)
+ if (dst) {
+ smp_mb__before_atomic_dec();
atomic_dec(&dst->__refcnt);
+ }
}
extern void * dst_alloc(struct dst_ops * ops);
diff -Nru a/net/core/dst.c b/net/core/dst.c
--- a/net/core/dst.c 2005-02-09 09:06:27 -08:00
+++ b/net/core/dst.c 2005-02-09 09:06:27 -08:00
@@ -142,8 +142,13 @@
void dst_destroy(struct dst_entry * dst)
{
- struct neighbour *neigh = dst->neighbour;
- struct hh_cache *hh = dst->hh;
+ struct neighbour *neigh;
+ struct hh_cache *hh;
+
+ smp_rmb();
+
+ neigh = dst->neighbour;
+ hh = dst->hh;
dst->hh = NULL;
if (hh && atomic_dec_and_test(&hh->hh_refcnt))
-
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