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

Commit c5a1ae9a authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
Browse files

[DCCP] ccid3: Perform history operations only after packet has been sent 



 This migrates all packet history operations into the routine
 ccid3_hc_tx_packet_sent, thereby removing synchronization problems
 that occur when, as before, the operations are spread over multiple
 routines.
 The following minor simplifications are also applied:
  * several simplifications now follow from this change - several tests
    are now no longer required
  * removal of one unnecessary variable (dp)

Justification:

 Currently packet history operations span two different routines,
 one of which is likely to pass through several iterations of sleeping
 and awakening.
 The first routine, ccid3_hc_tx_send_packet, allocates an entry and
 sets a few fields. The remaining fields are filled in when the second
 routine (which is not within a sleeping context), ccid3_hc_tx_packet_sent,
 is called. This has several strong drawbacks:
  * it is not necessary to split history operations - all fields can be
    filled in by the second routine
  * the first routine is called multiple times, until a packet can be sent,
    and sleeps meanwhile - this causes a lot of difficulties with regard to
    keeping the list consistent
  * since both routines do not have a producer-consumer like synchronization,
    it is very difficult to maintain data across calls to these routines
  * the fact that the routines are called in different contexts (sleeping, not
    sleeping) adds further problems

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@mandriva.com>
parent e312d100

net/dccp/ccids/ccid3.c

+9 −29
Original line number Diff line number Diff line
@@ -296,7 +296,6 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 
{

	struct dccp_sock *dp = dccp_sk(sk);

	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	struct dccp_tx_hist_entry *new_packet;

	struct timeval now;

	suseconds_t delay;
@@ -310,21 +309,6 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 
	if (unlikely(skb->len == 0))

		return -EBADMSG;



	/* See if last packet allocated was not sent */

	new_packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);

	if (new_packet == NULL || new_packet->dccphtx_sent) {

		new_packet = dccp_tx_hist_entry_new(ccid3_tx_hist,

						    GFP_ATOMIC);



		if (unlikely(new_packet == NULL)) {

			DCCP_WARN("%s, sk=%p, not enough mem to add to history,"

				  "send refused\n", dccp_role(sk), sk);

			return -ENOBUFS;

		}



		dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, new_packet);

	}



	dccp_timestamp(sk, &now);



	switch (hctx->ccid3hctx_state) {
@@ -380,31 +364,27 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 


static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)

{

	const struct dccp_sock *dp = dccp_sk(sk);

	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	struct timeval now;

	struct dccp_tx_hist_entry *packet;



	BUG_ON(hctx == NULL);



	dccp_timestamp(sk, &now);



	ccid3_hc_tx_update_s(hctx, len);



	packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);

	packet = dccp_tx_hist_entry_new(ccid3_tx_hist, GFP_ATOMIC);

	if (unlikely(packet == NULL)) {

		DCCP_WARN("packet doesn't exist in history!\n");

		return;

	}

	if (unlikely(packet->dccphtx_sent)) {

		DCCP_WARN("no unsent packet in history!\n");

		DCCP_CRIT("packet history - out of memory!");

		return;

	}

	dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, packet);



	dccp_timestamp(sk, &now);

	packet->dccphtx_tstamp = now;

	packet->dccphtx_seqno  = dp->dccps_gss;

	hctx->ccid3hctx_idle = 0;

	packet->dccphtx_seqno  = dccp_sk(sk)->dccps_gss;

	packet->dccphtx_rtt    = hctx->ccid3hctx_rtt;

	packet->dccphtx_sent   = 1;

	hctx->ccid3hctx_idle   = 0;

}



static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)