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7801db8aec
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>