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>
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@ -38,6 +38,7 @@
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#include <linux/errno.h>
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#include <linux/rtnetlink.h>
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#include <linux/skbuff.h>
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#include <linux/bitmap.h>
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#include <net/netlink.h>
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#include <net/act_api.h>
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#include <net/pkt_cls.h>
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@ -460,17 +461,25 @@ static int u32_delete(struct tcf_proto *tp, unsigned long arg)
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return 0;
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}
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#define NR_U32_NODE (1<<12)
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static u32 gen_new_kid(struct tc_u_hnode *ht, u32 handle)
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{
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struct tc_u_knode *n;
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unsigned int i = 0x7FF;
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unsigned long i;
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unsigned long *bitmap = kzalloc(BITS_TO_LONGS(NR_U32_NODE) * sizeof(unsigned long),
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GFP_KERNEL);
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if (!bitmap)
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return handle | 0xFFF;
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for (n = ht->ht[TC_U32_HASH(handle)]; n; n = n->next)
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if (i < TC_U32_NODE(n->handle))
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i = TC_U32_NODE(n->handle);
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i++;
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set_bit(TC_U32_NODE(n->handle), bitmap);
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return handle | (i > 0xFFF ? 0xFFF : i);
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i = find_next_zero_bit(bitmap, NR_U32_NODE, 0x800);
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if (i >= NR_U32_NODE)
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i = find_next_zero_bit(bitmap, NR_U32_NODE, 1);
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kfree(bitmap);
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return handle | (i >= NR_U32_NODE ? 0xFFF : i);
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}
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static const struct nla_policy u32_policy[TCA_U32_MAX + 1] = {
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