diff mbox

[4/5] Adds options DROPPED PACKETS and LOSS INTERVALS to receiver

Message ID 20090913184128.GA7165@gerrit.erg.abdn.ac.uk
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Gerrit Renker Sept. 13, 2009, 6:41 p.m. UTC 
| Adds options DROPPED PACKETS and LOSS INTERVALS to receiver. In this patch is added the
| mechanism of gathering information about loss intervals and storing it, for later
| construction of these two options.
This also needs some more work, please see inline.

 	return (DCCP_SKB_CB(skb)->dccpd_ecn & INET_ECN_MASK) == INET_ECN_CE;
 }
 
+static inline bool dccp_skb_is_ecn_ect0(const struct sk_buff *skb)
+{
+	return (DCCP_SKB_CB(skb)->dccpd_ecn & INET_ECN_MASK) == INET_ECN_ECT_0;
+}
+
+static inline bool dccp_skb_is_ecn_ect1(const struct sk_buff *skb)
+{
+	return (DCCP_SKB_CB(skb)->dccpd_ecn & INET_ECN_MASK) == INET_ECN_ECT_0;
+}
The routines are not needed, because the dccpd_ecn field is (deliberately) only
2 bits wide. In the second case it should have been INET_ECN_ECT_1.
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Comments

Ivo Calado Sept. 15, 2009, 12:40 a.m. UTC | #1 
The comments follow below


On Sun, Sep 13, 2009 at 15:41, Gerrit Renker <gerrit@erg.abdn.ac.uk> wrote:
> | Adds options DROPPED PACKETS and LOSS INTERVALS to receiver. In this patch is added the
> | mechanism of gathering information about loss intervals and storing it, for later
> | construction of these two options.
> This also needs some more work, please see inline.
>

<snip>

>
> +       tfrc_sp_update_li_data(ld, h, skb, new_loss, new_event);
> +
> I don't understand why 'tfrc_sp_update_li_data' is called twice, one call seems
> to be redundant. What it seems to be wanting to do is

When we are designing the loss count algorithm it seemed to be
necessary, but now that i need to revise this (patch nº 2),  I'll
observe this.


>        bool new_loss = false;
>
>        //...
<snip>
> at the begin of the function, all subsequent 'dccp_data_packet(skb)' are unnecessary.
> Almost every 'if' statement ends in 'return', this seems ad-hoc and could be reduced
> by adding if-else-if-else-if..., which would probably also reduce the code duplication.
>

I'll try to reduce code duplication, thanks.

>
> @@ -244,8 +463,11 @@
>        tfrc_lh_slab = kmem_cache_create("tfrc_sp_li_hist",
>                                         sizeof(struct tfrc_loss_interval), 0,
>                                         SLAB_HWCACHE_ALIGN, NULL);
> +       tfrc_ld_slab = kmem_cache_create("tfrc_sp_li_data",
> +                                        sizeof(struct tfrc_loss_data_entry), 0,
> +                                        SLAB_HWCACHE_ALIGN, NULL);
>
> -       if ((tfrc_lh_slab != NULL))
> +       if ((tfrc_lh_slab != NULL) || (tfrc_ld_slab != NULL))
>                return 0;
>
>        if (tfrc_lh_slab != NULL) {
> @@ -253,6 +475,11 @@
>                tfrc_lh_slab = NULL;
>        }
>
> +       if (tfrc_ld_slab != NULL) {
> +               kmem_cache_destroy(tfrc_ld_slab);
> +               tfrc_ld_slab = NULL;
> +       }
> +
>        return -ENOBUFS;
>  }
> The condition above should be '&&', not '||'. Suggested alternative:
>
> +       if (tfrc_lh_slab == NULL)
> +               goto lh_failed;
> +
> +       tfrc_ld_slab = kmem_cache_create("tfrc_sp_li_data",
> +                                        sizeof(struct tfrc_loss_data_entry), 0,
> +                                        SLAB_HWCACHE_ALIGN, NULL);
> +       if (tfrc_ld_slab != NULL)
> +               return 0;
> +
> +       kmem_cache_destroy(tfrc_lh_slab);
> +       tfrc_lh_slab = NULL;
> +lh_failed:
> +       return -ENOBUFS;
>  }
>

Thanks for revising this. Adding one label for each failure case will
not scale well. In another patch it will be needed to create another
structure, and so, requiring another label.



>
>
>
> --- dccp_tree_work5.orig/net/dccp/ccids/lib/loss_interval_sp.h
> +++ dccp_tree_work5/net/dccp/ccids/lib/loss_interval_sp.h
> @@ -70,13 +70,52 @@
>  struct tfrc_rx_hist;
>  #endif
>
> +struct tfrc_loss_data_entry {
> +       struct tfrc_loss_data_entry     *next;
> +       u32                             lossless_length:24;
> +       u8                              ecn_nonce_sum:1;
> +       u32                             loss_length:24;
> +       u32                             data_length:24;
> +       u32                             drop_count:24;
> +};
> According to RFC 4342, 8.6.1, Loss Length is a 23-bit number, i.e.
>        u32                             loss_length:23;
>

Thanks!

>
>
>
> +#define TFRC_LOSS_INTERVALS_OPT_MAX_LENGTH     28
> +#define TFRC_DROP_OPT_MAX_LENGTH               84
> +#define TFRC_LI_OPT_SZ \
> +       (2 + TFRC_LOSS_INTERVALS_OPT_MAX_LENGTH*9)
> +#define TFRC_DROPPED_OPT_SZ \
> +       (1 + TFRC_DROP_OPT_MAX_LENGTH*3)
> It would be good to have a reminder where the numbers come from, i.e.
>  * the "28" comes from RFC 4342, 8.6
>  * the "84" comes from RFC 5622, 8.7
>  * the "9" again is from RFC 4342, 8.6
>  * the 1 + TFRC_DROP_OPT_MAX_LENGTH*3 = DCCP_SINGLE_OPT_MAXLEN (linux/dccp.h)
>
Sorry, this documentation was written, but i left it in another future patch.

>
> +struct tfrc_loss_data {
> +       struct tfrc_loss_data_entry     *head;
> +       u16                             counter;
> +       u8                              loss_intervals_opts[TFRC_LI_OPT_SZ];
> +       u8                              drop_opts[TFRC_DROPPED_OPT_SZ];
> +       u8                              last_loss_count;
> +       u8                              sto_ecn;
> +       u8                              sto_is_data;
> +};
>
>
>
> +static inline void tfrc_ld_init(struct tfrc_loss_data *ld)
> +{
> +       memset(ld, 0, sizeof(struct tfrc_loss_data));
> +}
> A tip from CodingStyle - using "sizeof(*ld)" will continue to work if there
> are changes in the interface.
>

Thanks.


>
> --- dccp_tree_work5.orig/net/dccp/dccp.h
> +++ dccp_tree_work5/net/dccp/dccp.h
> @@ -403,6 +403,16 @@
>        return (DCCP_SKB_CB(skb)->dccpd_ecn & INET_ECN_MASK) == INET_ECN_CE;
>  }
>
> +static inline bool dccp_skb_is_ecn_ect0(const struct sk_buff *skb)
> +{
> +       return (DCCP_SKB_CB(skb)->dccpd_ecn & INET_ECN_MASK) == INET_ECN_ECT_0;
> +}
> +
> +static inline bool dccp_skb_is_ecn_ect1(const struct sk_buff *skb)
> +{
> +       return (DCCP_SKB_CB(skb)->dccpd_ecn & INET_ECN_MASK) == INET_ECN_ECT_0;
> +}
> The routines are not needed, because the dccpd_ecn field is (deliberately) only
> 2 bits wide. In the second case it should have been INET_ECN_ECT_1.
>

And how would be to determine if one packet's ecn is set to ECT 0 or ECT 1?
Gerrit Renker Sept. 19, 2009, 1:16 p.m. UTC | #2 
>> | Adds options DROPPED PACKETS and LOSS INTERVALS to receiver.
I must admit that I did not look at this deeply enough to be able to
say whether it would work or not. The comments that were sent were after
the first reading.

Whether to add the Loss Intervals / Dropped Packet options is related to
the question in patch 2/5. This needs to be clarified first: you do add
the Loss Intervals option, but if you do it, the division of the loss
intervals is not necessary - unless I am missing something here, this
computation is done by the sender.

If I understand RFC 4342/4828/5622 correctly, the sender would need to
keep track of the RTTs for each sent loss interval. Since the loss
interval boundaries are set by the receiver, the sender would need to
store the window counter value (or the RTT). RFC 4828 is a bit misleading
since it quotes RFC 3448/5348 (where the receiver computes the loss
event rate), whereas CCID-4 is based on RFC 4342 (where the sender
normally computes the loss event rate).



>> The condition above should be '&&', not '||'. Suggested alternative:
>>
>> +       if (tfrc_lh_slab == NULL)
>> +               goto lh_failed;
>> +
>> +       tfrc_ld_slab = kmem_cache_create("tfrc_sp_li_data",
>> +                                        sizeof(struct
>> tfrc_loss_data_entry), 0,
>> +                                        SLAB_HWCACHE_ALIGN, NULL);
>> +       if (tfrc_ld_slab != NULL)
>> +               return 0;
>> +
>> +       kmem_cache_destroy(tfrc_lh_slab);
>> +       tfrc_lh_slab = NULL;
>> +lh_failed:
>> +       return -ENOBUFS;
>>  }
>>
>
> Thanks for revising this. Adding one label for each failure case will
> not scale well. In another patch it will be needed to create another
> structure, and so, requiring another label.
Using such labels follows a coding convention in the networking code.
As an example, consider ip4_init_mib_net() in net/ipv4/af_inet.c.

The pattern is that if step n fails, it does a rollback, undoing all
preceding initialisations in the reverse order. I think this is also
in agreement with Documentation/CodingStyle, chap. 7.




> And how would be to determine if one packet's ecn is set to ECT 0 or ECT
> 1?
It should be possible to use '==' directly, i.e.
switch (DCCP_SKB_CB(skb)->dccpd_ecn) {
case  INET_ECN_NOT_ECT:  // ECN not enabled
case  INET_ECN_ECT_1:    // ECT(1), see below
case  INET_ECN_ECT_0:    // ECT(0)
case  INET_ECN_CE:       // congestion
}

However, the kernel currently only supports ECT(0). Resolving this is
ongoing work in another thread. For the moment, it simplifies the ECN
nonce verification; as per figure 1 in RFC 3540, the sum will always
be 0 if only ECT(0) is used.

This would allow to write a function stub for ECN nonce verification,
which for the moment only does something like

bool dccp_verify_ecn_nonce(const u8 sum)
{
      return sum == 0;
}

The same "fix" has currently been put into the Ack Vector nonce sum,
this is in
http://eden-feed.erg.abdn.ac.uk/cgi-bin/gitweb.cgi?p=dccp_exp.git;\
a=commitdiff;h=50e6081f6ff37102ac5f92df85f017e2c15f338a

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diff mbox

Patch

--- dccp_tree_work5.orig/net/dccp/ccids/lib/packet_history_sp.c
+++ dccp_tree_work5/net/dccp/ccids/lib/packet_history_sp.c
@@ -233,7 +233,9 @@ 
 }
 
 /* return 1 if a new loss event has been identified */
-static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3)
+static int __two_after_loss(struct tfrc_rx_hist *h,
+			    struct sk_buff *skb, u32 n3,
+			    bool *new_loss)
 {
 	u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
 	    s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
@@ -245,6 +247,7 @@ 
 		tfrc_sp_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3),
 					       skb, n3);
 		h->num_losses = dccp_loss_count(s2, s3, n3);
+		*new_loss = 1;
 		return 1;
 	}
 
@@ -259,6 +262,7 @@ 
 					       skb, n3);
 		h->loss_count = 3;
 		h->num_losses = dccp_loss_count(s1, s3, n3);
+		*new_loss = 1;
 		return 1;
 	}
 
@@ -284,6 +288,7 @@ 
 			tfrc_sp_rx_hist_entry_from_skb(
 					tfrc_rx_hist_loss_prev(h), skb, n3);
 
+		*new_loss = 0;
 		return 0;
 	}
 
@@ -297,6 +302,7 @@ 
 	h->loss_count = 3;
 	h->num_losses = dccp_loss_count(s0, s3, n3);
 
+	*new_loss = 1;
 	return 1;
 }
The 'new_loss' parameter is completely redundant, since it duplicates the
return value of the function.


@@ -348,11 +354,14 @@ 
  *  operations when loss_count is greater than 0 after calling this function.
  */
 bool tfrc_sp_rx_congestion_event(struct tfrc_rx_hist *h,
-			      struct tfrc_loss_hist *lh,
-	 struct sk_buff *skb, const u64 ndp,
-  u32 (*first_li)(struct sock *), struct sock *sk)
+				 struct tfrc_loss_hist *lh,
+				 struct tfrc_loss_data *ld,
+				 struct sk_buff *skb, const u64 ndp,
+				 u32 (*first_li)(struct sock *),
+				 struct sock *sk)
 {
 	bool new_event = false;
+	bool new_loss = false;
 
 	if (tfrc_sp_rx_hist_duplicate(h, skb))
 		return 0;
@@ -365,12 +374,13 @@ 
 		__one_after_loss(h, skb, ndp);
 	} else if (h->loss_count != 2) {
 		DCCP_BUG("invalid loss_count %d", h->loss_count);
-	} else if (__two_after_loss(h, skb, ndp)) {
+	} else if (__two_after_loss(h, skb, ndp, &new_loss)) {
 		/*
 		* Update Loss Interval database and recycle RX records
 		*/
 		new_event = tfrc_sp_lh_interval_add(lh, h, first_li, sk,
 						dccp_hdr(skb)->dccph_ccval);
+		tfrc_sp_update_li_data(ld, h, skb, new_loss, new_event);
 		__three_after_loss(h);
 
 	} else if (dccp_data_packet(skb) && dccp_skb_is_ecn_ce(skb)) {
@@ -396,6 +406,8 @@ 
 		}
 	}
 
+	tfrc_sp_update_li_data(ld, h, skb, new_loss, new_event);
+
I don't understand why 'tfrc_sp_update_li_data' is called twice, one call seems
to be redundant. What it seems to be wanting to do is
	bool new_loss = false;

	//...
	} else if (__two_after_loss(h, skb, ndp)) {
		new_loss  = true;
		new_event = tfrc_sp_lh_interval_add(...);
		// ...
	}
	// ...
	tfrc_sp_update_li_data(ld, h, skb, new_loss, new_event);
	


--- dccp_tree_work5.orig/net/dccp/ccids/lib/loss_interval_sp.c
+++ dccp_tree_work5/net/dccp/ccids/lib/loss_interval_sp.c
 
+void tfrc_sp_ld_cleanup(struct tfrc_loss_data *ld)
+{
+	struct tfrc_loss_data_entry *next, *h = ld->head;
+
+	if (!h)
+		return;
+
+	while (h) {
+		next = h->next;
+		kmem_cache_free(tfrc_ld_slab, h);
+		h = next;
+	}
+
+	ld->head = NULL;
+	ld->counter = 0;
+}
The if(!h) statement is not needed above and prevents resetting 
the head/counter values.


+void tfrc_sp_ld_prepare_data(u8 loss_count, struct tfrc_loss_data *ld)
+{
+	u8 *li_ofs, *d_ofs;
+	struct tfrc_loss_data_entry *e;
+	u16 count;
+
+	li_ofs = &ld->loss_intervals_opts[0];
+	d_ofs = &ld->drop_opts[0];
+
+	count = 0;
+	e = ld->head;
+
+	*li_ofs = loss_count + 1;
+	li_ofs++;
+
+	while (e != NULL) {
+
+		if (count < TFRC_LOSS_INTERVALS_OPT_MAX_LENGTH) {
+			*li_ofs = ((htonl(e->lossless_length) & 0x00FFFFFF)<<8);
+			li_ofs += 3;
+			*li_ofs = ((e->ecn_nonce_sum&0x1) << 31) &
+				  (htonl((e->loss_length & 0x00FFFFFF))<<8);
==> This does not seem right: mixing htonl with non-htonl data, using '&' where
    probably '|' is meant.
+			li_ofs += 3;
+			*li_ofs = ((htonl(e->data_length) & 0x00FFFFFF)<<8);
==> I think you mean "e->data_length & 0xFFFFFF".

+			li_ofs += 3;
+		}
+
+		if (count < TFRC_DROP_OPT_MAX_LENGTH) {
+			*d_ofs = (htonl(e->drop_count) & 0x00FFFFFF)<<8;
+			d_ofs += 3;
+		}
+
+		if ((count >= TFRC_LOSS_INTERVALS_OPT_MAX_LENGTH) &&
+		    (count >= TFRC_DROP_OPT_MAX_LENGTH))
+			break;
==> This could be better handled using 'else' cases above, it seems the '&&' means '||'.
+
+		count++;
+		e = e->next;
+	}
+}

+void tfrc_sp_update_li_data(struct tfrc_loss_data *ld,
+			    struct tfrc_rx_hist *rh,
+			    struct sk_buff *skb,
+			    bool new_loss, bool new_event)
+{
+	struct tfrc_loss_data_entry *new, *h;
+
+	if (!dccp_data_packet(skb))
+		return;
+
+	if (ld->head == NULL) {
+		new = tfrc_ld_add_new(ld);
+		if (unlikely(new == NULL)) {
+			DCCP_CRIT("Cannot allocate new loss data registry.");
+			return;
+		}
+
+		if (new_loss) {
+			new->drop_count = rh->num_losses;
+			new->lossless_length = 1;
+			new->loss_length = rh->num_losses;
+
+			if (dccp_data_packet(skb))
+				new->data_length = 1;
+
+			if (dccp_data_packet(skb) && dccp_skb_is_ecn_ect1(skb))
+				new->ecn_nonce_sum = 1;
+			else
+				new->ecn_nonce_sum = 0;
+		} else {
+			new->drop_count = 0;
+			new->lossless_length = 1;
+			new->loss_length = 0;
+
+			if (dccp_data_packet(skb))
+				new->data_length = 1;
+
+			if (dccp_data_packet(skb) && dccp_skb_is_ecn_ect1(skb))
+				new->ecn_nonce_sum = 1;
+			else
+				new->ecn_nonce_sum = 0;
+		}
+
+		return;
+	}
+
+	if (new_event) {
+		new = tfrc_ld_add_new(ld);
+		if (unlikely(new == NULL)) {
+			DCCP_CRIT("Cannot allocate new loss data registry. \
+					Cleaning up.");
+			tfrc_sp_ld_cleanup(ld);
+			return;
+		}
+
+		new->drop_count = rh->num_losses;
+		new->lossless_length = (ld->last_loss_count - rh->loss_count);
+		new->loss_length = rh->num_losses;
+
+		new->ecn_nonce_sum = 0;
+		new->data_length = 0;
+
+		while (ld->last_loss_count > rh->loss_count) {
+			ld->last_loss_count--;
+
+			if (ld->sto_is_data & (1 << (ld->last_loss_count))) {
+				new->data_length++;
+
+				if (ld->sto_ecn & (1 << (ld->last_loss_count)))
+					new->ecn_nonce_sum =
+						!new->ecn_nonce_sum;
+			}
+		}
+
+		return;
+	}
+
+	h = ld->head;
+
+	if (rh->loss_count > ld->last_loss_count) {
+		ld->last_loss_count = rh->loss_count;
+
+		if (dccp_data_packet(skb))
+			ld->sto_is_data |= (1 << (ld->last_loss_count - 1));
+
+		if (dccp_skb_is_ecn_ect1(skb))
+			ld->sto_ecn |= (1 << (ld->last_loss_count - 1));
+
+		return;
+	}
+
+	if (new_loss) {
+		h->drop_count += rh->num_losses;
+		h->lossless_length = (ld->last_loss_count - rh->loss_count);
+		h->loss_length += h->lossless_length + rh->num_losses;
+
+		h->ecn_nonce_sum = 0;
+		h->data_length = 0;
+
+		while (ld->last_loss_count > rh->loss_count) {
+			ld->last_loss_count--;
+
+			if (ld->sto_is_data&(1 << (ld->last_loss_count))) {
+				h->data_length++;
+
+				if (ld->sto_ecn & (1 << (ld->last_loss_count)))
+					h->ecn_nonce_sum = !h->ecn_nonce_sum;
+			}
+		}
+
+		return;
+	}
+
+	if (ld->last_loss_count > rh->loss_count) {
+		while (ld->last_loss_count > rh->loss_count) {
+			ld->last_loss_count--;
+
+			h->lossless_length++;
+
+			if (ld->sto_is_data & (1 << (ld->last_loss_count))) {
+				h->data_length++;
+
+				if (ld->sto_ecn & (1 << (ld->last_loss_count)))
+					h->ecn_nonce_sum = !h->ecn_nonce_sum;
+			}
+		}
+
+		return;
+	}
+
+	h->lossless_length++;
+
+	if (dccp_data_packet(skb)) {
+		h->data_length++;
+
+		if (dccp_skb_is_ecn_ect1(skb))
+			h->ecn_nonce_sum = !h->ecn_nonce_sum;
+	}
+}
Due to the 
       if (!dccp_data_packet(skb))
               return;
at the begin of the function, all subsequent 'dccp_data_packet(skb)' are unnecessary.
Almost every 'if' statement ends in 'return', this seems ad-hoc and could be reduced
by adding if-else-if-else-if..., which would probably also reduce the code duplication.


@@ -244,8 +463,11 @@ 
 	tfrc_lh_slab = kmem_cache_create("tfrc_sp_li_hist",
 					 sizeof(struct tfrc_loss_interval), 0,
 					 SLAB_HWCACHE_ALIGN, NULL);
+	tfrc_ld_slab = kmem_cache_create("tfrc_sp_li_data",
+					 sizeof(struct tfrc_loss_data_entry), 0,
+					 SLAB_HWCACHE_ALIGN, NULL);
 
-	if ((tfrc_lh_slab != NULL))
+	if ((tfrc_lh_slab != NULL) || (tfrc_ld_slab != NULL))
 		return 0;
 
 	if (tfrc_lh_slab != NULL) {
@@ -253,6 +475,11 @@ 
 		tfrc_lh_slab = NULL;
 	}
 
+	if (tfrc_ld_slab != NULL) {
+		kmem_cache_destroy(tfrc_ld_slab);
+		tfrc_ld_slab = NULL;
+	}
+
 	return -ENOBUFS;
 }
The condition above should be '&&', not '||'. Suggested alternative:

+	if (tfrc_lh_slab == NULL)
+		goto lh_failed;
+
+	tfrc_ld_slab = kmem_cache_create("tfrc_sp_li_data",
+					 sizeof(struct tfrc_loss_data_entry), 0,
+					 SLAB_HWCACHE_ALIGN, NULL);
+	if (tfrc_ld_slab != NULL)
+		return 0;
+
+	kmem_cache_destroy(tfrc_lh_slab);
+	tfrc_lh_slab = NULL;
+lh_failed:
+	return -ENOBUFS;
 }
 



--- dccp_tree_work5.orig/net/dccp/ccids/lib/loss_interval_sp.h
+++ dccp_tree_work5/net/dccp/ccids/lib/loss_interval_sp.h
@@ -70,13 +70,52 @@ 
 struct tfrc_rx_hist;
 #endif
 
+struct tfrc_loss_data_entry {
+	struct tfrc_loss_data_entry	*next;
+	u32				lossless_length:24;
+	u8				ecn_nonce_sum:1;
+	u32				loss_length:24;
+	u32				data_length:24;
+	u32				drop_count:24;
+};
According to RFC 4342, 8.6.1, Loss Length is a 23-bit number, i.e.
	u32				loss_length:23;




+#define TFRC_LOSS_INTERVALS_OPT_MAX_LENGTH	28
+#define TFRC_DROP_OPT_MAX_LENGTH		84
+#define TFRC_LI_OPT_SZ	\
+	(2 + TFRC_LOSS_INTERVALS_OPT_MAX_LENGTH*9)
+#define TFRC_DROPPED_OPT_SZ \
+	(1 + TFRC_DROP_OPT_MAX_LENGTH*3)
It would be good to have a reminder where the numbers come from, i.e.
 * the "28" comes from RFC 4342, 8.6
 * the "84" comes from RFC 5622, 8.7
 * the "9" again is from RFC 4342, 8.6
 * the 1 + TFRC_DROP_OPT_MAX_LENGTH*3 = DCCP_SINGLE_OPT_MAXLEN (linux/dccp.h)


+struct tfrc_loss_data {
+	struct tfrc_loss_data_entry	*head;
+	u16				counter;
+	u8				loss_intervals_opts[TFRC_LI_OPT_SZ];
+	u8				drop_opts[TFRC_DROPPED_OPT_SZ];
+	u8				last_loss_count;
+	u8				sto_ecn;
+	u8				sto_is_data;
+};



+static inline void tfrc_ld_init(struct tfrc_loss_data *ld)
+{
+	memset(ld, 0, sizeof(struct tfrc_loss_data));
+}
A tip from CodingStyle - using "sizeof(*ld)" will continue to work if there
are changes in the interface.


--- dccp_tree_work5.orig/net/dccp/dccp.h
+++ dccp_tree_work5/net/dccp/dccp.h
@@ -403,6 +403,16 @@