net-sched: cls_flow: add perturbation support

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 44 insertions, 9 deletions

diff --git a/include/linux/pkt_cls.h b/include/linux/pkt_cls.h
index 99efbed81fa2..7cf7824df778 100644
--- a/include/linux/pkt_cls.h
+++ b/include/linux/pkt_cls.h
@@ -374,6 +374,7 @@ enum
         TCA_FLOW_ACT,
         TCA_FLOW_POLICE,
         TCA_FLOW_EMATCHES,
+        TCA_FLOW_PERTURB,
         __TCA_FLOW_MAX
 };
 
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index 971b867e0484..8f63a1a94014 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -36,6 +36,8 @@ struct flow_filter {
         struct list_head        list;
         struct tcf_exts         exts;
         struct tcf_ematch_tree  ematches;
+        struct timer_list       perturb_timer;
+        u32                     perturb_period;
         u32                     handle;
 
         u32                     nkeys;
@@ -47,11 +49,9 @@ struct flow_filter {
         u32                     addend;
         u32                     divisor;
         u32                     baseclass;
+        u32                     hashrnd;
 };
 
-static u32 flow_hashrnd __read_mostly;
-static int flow_hashrnd_initted __read_mostly;
-
 static const struct tcf_ext_map flow_ext_map = {
         .action = TCA_FLOW_ACT,
         .police = TCA_FLOW_POLICE,
@@ -348,7 +348,7 @@ static int flow_classify(struct sk_buff *skb, struct tcf_proto *tp,
                 }
 
                 if (f->mode == FLOW_MODE_HASH)
-                        classid = jhash2(keys, f->nkeys, flow_hashrnd);
+                        classid = jhash2(keys, f->nkeys, f->hashrnd);
                 else {
                         classid = keys[0];
                         classid = (classid & f->mask) ^ f->xor;
@@ -369,6 +369,15 @@ static int flow_classify(struct sk_buff *skb, struct tcf_proto *tp,
         return -1;
 }
 
+static void flow_perturbation(unsigned long arg)
+{
+        struct flow_filter *f = (struct flow_filter *)arg;
+
+        get_random_bytes(&f->hashrnd, 4);
+        if (f->perturb_period)
+                mod_timer(&f->perturb_timer, jiffies + f->perturb_period);
+}
+
 static const struct nla_policy flow_policy[TCA_FLOW_MAX + 1] = {
         [TCA_FLOW_KEYS]         = { .type = NLA_U32 },
         [TCA_FLOW_MODE]         = { .type = NLA_U32 },
@@ -381,6 +390,7 @@ static const struct nla_policy flow_policy[TCA_FLOW_MAX + 1] = {
         [TCA_FLOW_ACT]          = { .type = NLA_NESTED },
         [TCA_FLOW_POLICE]       = { .type = NLA_NESTED },
         [TCA_FLOW_EMATCHES]     = { .type = NLA_NESTED },
+        [TCA_FLOW_PERTURB]      = { .type = NLA_U32 },
 };
 
 static int flow_change(struct tcf_proto *tp, unsigned long base,
@@ -394,6 +404,7 @@ static int flow_change(struct tcf_proto *tp, unsigned long base,
         struct tcf_exts e;
         struct tcf_ematch_tree t;
         unsigned int nkeys = 0;
+        unsigned int perturb_period = 0;
         u32 baseclass = 0;
         u32 keymask = 0;
         u32 mode;
@@ -442,6 +453,14 @@ static int flow_change(struct tcf_proto *tp, unsigned long base,
                         mode = nla_get_u32(tb[TCA_FLOW_MODE]);
                 if (mode != FLOW_MODE_HASH && nkeys > 1)
                         goto err2;
+
+                if (mode == FLOW_MODE_HASH)
+                        perturb_period = f->perturb_period;
+                if (tb[TCA_FLOW_PERTURB]) {
+                        if (mode != FLOW_MODE_HASH)
+                                goto err2;
+                        perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
+                }
         } else {
                 err = -EINVAL;
                 if (!handle)
@@ -455,6 +474,12 @@ static int flow_change(struct tcf_proto *tp, unsigned long base,
                 if (mode != FLOW_MODE_HASH && nkeys > 1)
                         goto err2;
 
+                if (tb[TCA_FLOW_PERTURB]) {
+                        if (mode != FLOW_MODE_HASH)
+                                goto err2;
+                        perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
+                }
+
                 if (TC_H_MAJ(baseclass) == 0)
                         baseclass = TC_H_MAKE(tp->q->handle, baseclass);
                 if (TC_H_MIN(baseclass) == 0)
@@ -467,6 +492,11 @@ static int flow_change(struct tcf_proto *tp, unsigned long base,
 
                 f->handle = handle;
                 f->mask   = ~0U;
+
+                get_random_bytes(&f->hashrnd, 4);
+                f->perturb_timer.function = flow_perturbation;
+                f->perturb_timer.data = (unsigned long)f;
+                init_timer_deferrable(&f->perturb_timer);
         }
 
         tcf_exts_change(tp, &f->exts, &e);
@@ -495,6 +525,11 @@ static int flow_change(struct tcf_proto *tp, unsigned long base,
         if (baseclass)
                 f->baseclass = baseclass;
 
+        f->perturb_period = perturb_period;
+        del_timer(&f->perturb_timer);
+        if (perturb_period)
+                mod_timer(&f->perturb_timer, jiffies + perturb_period);
+
         if (*arg == 0)
                 list_add_tail(&f->list, &head->filters);
 
@@ -512,6 +547,7 @@ err1:
 
 static void flow_destroy_filter(struct tcf_proto *tp, struct flow_filter *f)
 {
+        del_timer_sync(&f->perturb_timer);
         tcf_exts_destroy(tp, &f->exts);
         tcf_em_tree_destroy(tp, &f->ematches);
         kfree(f);
@@ -532,11 +568,6 @@ static int flow_init(struct tcf_proto *tp)
 {
         struct flow_head *head;
 
-        if (!flow_hashrnd_initted) {
-                get_random_bytes(&flow_hashrnd, 4);
-                flow_hashrnd_initted = 1;
-        }
-
         head = kzalloc(sizeof(*head), GFP_KERNEL);
         if (head == NULL)
                 return -ENOBUFS;
@@ -605,6 +636,9 @@ static int flow_dump(struct tcf_proto *tp, unsigned long fh,
         if (f->baseclass)
                 NLA_PUT_U32(skb, TCA_FLOW_BASECLASS, f->baseclass);
 
+        if (f->perturb_period)
+                NLA_PUT_U32(skb, TCA_FLOW_PERTURB, f->perturb_period / HZ);
+
         if (tcf_exts_dump(skb, &f->exts, &flow_ext_map) < 0)
                 goto nla_put_failure;
 #ifdef CONFIG_NET_EMATCH