Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4c70f383 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
Browse files

[DCCP]: Provide 10s of microsecond timesource 



This provides a timesource, conveniently used for DCCP timestamps, which
returns the elapsed time in 10s of microseconds since initialisation.
This makes for a wrap-around time of about 11.9 hours, which should be
sufficient for most applications.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent aa97efd9

net/dccp/dccp.h

+2 −0
Original line number Diff line number Diff line
@@ -396,6 +396,8 @@ extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb); 
extern int dccp_insert_option_elapsed_time(struct sock *sk,

					    struct sk_buff *skb,

					    u32 elapsed_time);

extern u32 dccp_timestamp(void);

extern void dccp_timestamping_init(void);

extern int dccp_insert_option_timestamp(struct sock *sk,

					 struct sk_buff *skb);

extern int dccp_insert_option(struct sock *sk, struct sk_buff *skb,

net/dccp/options.c

+1 −1
Original line number Diff line number Diff line
@@ -372,7 +372,7 @@ EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time); 


int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)

{

	__be32 now = htonl(((suseconds_t)ktime_to_us(ktime_get_real())) / 10);

	__be32 now = htonl(dccp_timestamp());

	/* yes this will overflow but that is the point as we want a

	 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */

net/dccp/proto.c

+2 −0
Original line number Diff line number Diff line
@@ -1076,6 +1076,8 @@ static int __init dccp_init(void) 
	rc = dccp_sysctl_init();

	if (rc)

		goto out_ackvec_exit;



	dccp_timestamping_init();

out:

	return rc;

out_ackvec_exit:

net/dccp/timer.c

+21 −0
Original line number Diff line number Diff line
@@ -291,3 +291,24 @@ void dccp_init_xmit_timers(struct sock *sk) 
	inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,

				  &dccp_keepalive_timer);

}



static ktime_t dccp_timestamp_seed;

/**

 * dccp_timestamp  -  10s of microseconds time source

 * Returns the number of 10s of microseconds since loading DCCP. This is native

 * DCCP time difference format (RFC 4340, sec. 13).

 * Please note: This will wrap around about circa every 11.9 hours.

 */

u32 dccp_timestamp(void)

{

	s64 delta = ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);



	do_div(delta, 10);

	return delta;

}

EXPORT_SYMBOL_GPL(dccp_timestamp);



void __init dccp_timestamping_init(void)

{

	dccp_timestamp_seed = ktime_get_real();

}