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author | Cong Wang <cwang@twopensource.com> | 2014-07-17 17:34:53 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2014-07-20 20:49:17 -0700 |
commit | 7801db8aec957fa6610efe0ee26a6c8bc0f1d73b (patch) | |
tree | 24c7a78ca03e5c6eff1b2b23d281d83c02e72788 /net/sched/cls_u32.c | |
parent | c2a6c7813f1ffae636e369b5d7011c9f518d3cd9 (diff) | |
download | linux-7801db8aec957fa6610efe0ee26a6c8bc0f1d73b.tar.gz linux-7801db8aec957fa6610efe0ee26a6c8bc0f1d73b.tar.bz2 linux-7801db8aec957fa6610efe0ee26a6c8bc0f1d73b.zip |
net_sched: avoid generating same handle for u32 filters
When kernel generates a handle for a u32 filter, it tries to start
from the max in the bucket. So when we have a filter with the max (fff)
handle, it will cause kernel always generates the same handle for new
filters. This can be shown by the following command:
tc qdisc add dev eth0 ingress
tc filter add dev eth0 parent ffff: protocol ip pref 770 handle 800::fff u32 match ip protocol 1 0xff
tc filter add dev eth0 parent ffff: protocol ip pref 770 u32 match ip protocol 1 0xff
...
we will get some u32 filters with same handle:
# tc filter show dev eth0 parent ffff:
filter protocol ip pref 770 u32
filter protocol ip pref 770 u32 fh 800: ht divisor 1
filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0
match 00010000/00ff0000 at 8
filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0
match 00010000/00ff0000 at 8
filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0
match 00010000/00ff0000 at 8
filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0
match 00010000/00ff0000 at 8
handles should be unique. This patch fixes it by looking up a bitmap,
so that can guarantee the handle is as unique as possible. For compatibility,
we still start from 0x800.
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/cls_u32.c')
-rw-r--r-- | net/sched/cls_u32.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index c39b583ace32..70c0be8d0121 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -38,6 +38,7 @@ #include <linux/errno.h> #include <linux/rtnetlink.h> #include <linux/skbuff.h> +#include <linux/bitmap.h> #include <net/netlink.h> #include <net/act_api.h> #include <net/pkt_cls.h> @@ -460,17 +461,25 @@ static int u32_delete(struct tcf_proto *tp, unsigned long arg) return 0; } +#define NR_U32_NODE (1<<12) static u32 gen_new_kid(struct tc_u_hnode *ht, u32 handle) { struct tc_u_knode *n; - unsigned int i = 0x7FF; + unsigned long i; + unsigned long *bitmap = kzalloc(BITS_TO_LONGS(NR_U32_NODE) * sizeof(unsigned long), + GFP_KERNEL); + if (!bitmap) + return handle | 0xFFF; for (n = ht->ht[TC_U32_HASH(handle)]; n; n = n->next) - if (i < TC_U32_NODE(n->handle)) - i = TC_U32_NODE(n->handle); - i++; + set_bit(TC_U32_NODE(n->handle), bitmap); - return handle | (i > 0xFFF ? 0xFFF : i); + i = find_next_zero_bit(bitmap, NR_U32_NODE, 0x800); + if (i >= NR_U32_NODE) + i = find_next_zero_bit(bitmap, NR_U32_NODE, 1); + + kfree(bitmap); + return handle | (i >= NR_U32_NODE ? 0xFFF : i); } static const struct nla_policy u32_policy[TCA_U32_MAX + 1] = { |