Commit 6b811d43 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
Browse files

[DCCP]: 48-bit sequence number arithmetic 



This patch
 * organizes the sequence arithmetic functions into one corner of dccp.h
 * performs a small modification of dccp_set_seqno to make it more widely reusable
   (now it is safe to use any number, since it performs modulo-2^48 assignment)
 * adds functions and generic macros for 48-bit sequence arithmetic:
 	--48 bit complement
 	--modulo-48 addition and modulo-48 subtraction
	--dccp_inc_seqno now a special case of add48
Constants renamed following a suggestion by Arnaldo.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8b5be268

net/dccp/ackvec.c

+1 −1
Original line number Diff line number Diff line
@@ -157,7 +157,7 @@ struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority) 


	if (av != NULL) {

		av->dccpav_buf_head	= DCCP_MAX_ACKVEC_LEN - 1;

		av->dccpav_buf_ackno	= DCCP_MAX_SEQNO + 1;

		av->dccpav_buf_ackno	= UINT48_MAX + 1;

		av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;

		av->dccpav_time.tv_sec	= 0;

		av->dccpav_time.tv_usec	= 0;

net/dccp/dccp.h

+27 −20
Original line number Diff line number Diff line
@@ -92,6 +92,32 @@ extern int sysctl_dccp_feat_send_ack_vector; 
extern int  sysctl_dccp_feat_send_ndp_count;

extern int  sysctl_dccp_tx_qlen;



/*

 *	48-bit sequence number arithmetic (signed and unsigned)

 */

#define INT48_MIN	  0x800000000000LL		/* 2^47	    */

#define UINT48_MAX	  0xFFFFFFFFFFFFLL		/* 2^48 - 1 */

#define COMPLEMENT48(x)	 (0x1000000000000LL - (x))	/* 2^48 - x */

#define TO_SIGNED48(x)	 (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))

#define TO_UNSIGNED48(x) (((x) >= 0)?	     (x) :  COMPLEMENT48(-(x)))

#define ADD48(a, b)	 (((a) + (b)) & UINT48_MAX)

#define SUB48(a, b)	 ADD48((a), COMPLEMENT48(b))



static inline void dccp_set_seqno(u64 *seqno, u64 value)

{

	*seqno = value & UINT48_MAX;

}



static inline void dccp_inc_seqno(u64 *seqno)

{

	*seqno = ADD48(*seqno, 1);

}



static inline u64 dccp_delta_seqno(u64 seqno1, u64 seqno2)

{

	return ((seqno2 << 16) - (seqno1 << 16)) >> 16;

}



/* is seq1 < seq2 ? */

static inline int before48(const u64 seq1, const u64 seq2)

{
@@ -313,26 +339,7 @@ static inline int dccp_packet_without_ack(const struct sk_buff *skb) 
	return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;

}



#define DCCP_MAX_SEQNO ((((u64)1) << 48) - 1)

#define DCCP_PKT_WITHOUT_ACK_SEQ (DCCP_MAX_SEQNO << 2)



static inline void dccp_set_seqno(u64 *seqno, u64 value)

{

	if (value > DCCP_MAX_SEQNO)

		value -= DCCP_MAX_SEQNO + 1;

	*seqno = value;

}



static inline u64 dccp_delta_seqno(u64 seqno1, u64 seqno2)

{

	return ((seqno2 << 16) - (seqno1 << 16)) >> 16;

}



static inline void dccp_inc_seqno(u64 *seqno)

{

	if (++*seqno > DCCP_MAX_SEQNO)

		*seqno = 0;

}

#define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)



static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)

{

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