diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-05-11 23:19:48 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-05-17 17:18:50 -0700 |
| commit | 7fee226ad2397b635e2fd565a59ca3ae08a164cd (patch) | |
| tree | 0bcd26150ad74ec1a237109de87a3d214a07fc22 /include/net/dst.h | |
| parent | ebda37c27d0c768947e9b058332d7ea798210cf8 (diff) | |
net: add a noref bit on skb dst
Use low order bit of skb->_skb_dst to tell dst is not refcounted.
Change _skb_dst to _skb_refdst to make sure all uses are catched.
skb_dst() returns the dst, regardless of noref bit set or not, but
with a lockdep check to make sure a noref dst is not given if current
user is not rcu protected.
New skb_dst_set_noref() helper to set an notrefcounted dst on a skb.
(with lockdep check)
skb_dst_drop() drops a reference only if skb dst was refcounted.
skb_dst_force() helper is used to force a refcount on dst, when skb
is queued and not anymore RCU protected.
Use skb_dst_force() in __sk_add_backlog(), __dev_xmit_skb() if
!IFF_XMIT_DST_RELEASE or skb enqueued on qdisc queue, in
sock_queue_rcv_skb(), in __nf_queue().
Use skb_dst_force() in dev_requeue_skb().
Note: dst_use_noref() still dirties dst, we might transform it
later to do one dirtying per jiffies.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/dst.h')
| -rw-r--r-- | include/net/dst.h | 48 |
1 files changed, 45 insertions, 3 deletions
diff --git a/include/net/dst.h b/include/net/dst.h index aac5a5fcfda9..27207a13f2a6 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -168,6 +168,12 @@ static inline void dst_use(struct dst_entry *dst, unsigned long time) dst->lastuse = time; } +static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) +{ + dst->__use++; + dst->lastuse = time; +} + static inline struct dst_entry * dst_clone(struct dst_entry * dst) { @@ -177,11 +183,47 @@ struct dst_entry * dst_clone(struct dst_entry * dst) } extern void dst_release(struct dst_entry *dst); + +static inline void refdst_drop(unsigned long refdst) +{ + if (!(refdst & SKB_DST_NOREF)) + dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); +} + +/** + * skb_dst_drop - drops skb dst + * @skb: buffer + * + * Drops dst reference count if a reference was taken. + */ static inline void skb_dst_drop(struct sk_buff *skb) { - if (skb->_skb_dst) - dst_release(skb_dst(skb)); - skb->_skb_dst = 0UL; + if (skb->_skb_refdst) { + refdst_drop(skb->_skb_refdst); + skb->_skb_refdst = 0UL; + } +} + +static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) +{ + nskb->_skb_refdst = oskb->_skb_refdst; + if (!(nskb->_skb_refdst & SKB_DST_NOREF)) + dst_clone(skb_dst(nskb)); +} + +/** + * skb_dst_force - makes sure skb dst is refcounted + * @skb: buffer + * + * If dst is not yet refcounted, let's do it + */ +static inline void skb_dst_force(struct sk_buff *skb) +{ + if (skb_dst_is_noref(skb)) { + WARN_ON(!rcu_read_lock_held()); + skb->_skb_refdst &= ~SKB_DST_NOREF; + dst_clone(skb_dst(skb)); + } } /* Children define the path of the packet through the |