This patch is thanks to an investigation by Leandro Sales de Melo and his
colleagues. They worked out two state diagrams which highlight the fact that
the xxx_TERM states in CCID-3/4 are in fact not necessary.
And this can be confirmed by in turn looking at the code: the xxx_TERM states
are only ever set in ccid3_hc_{rx,tx}_exit(). These two functions are part
of the following call chain:
* ccid_hc_{tx,rx}_exit() are called from ccid_delete() only;
* ccid_delete() invokes ccid_hc_{tx,rx}_exit() in the way of a destructor:
after calling ccid_hc_{tx,rx}_exit(), the CCID is released from memory;
* ccid_delete() is in turn called only by ccid_hc_{tx,rx}_delete();
* ccid_hc_{tx,rx}_delete() is called only if
- feature negotiation failed (dccp_feat_activate_values()),
- when changing the RX/TX CCID (to eject the current CCID),
- when destroying the socket (in dccp_destroy_sock()).
In other words, when CCID-3 sets the state to xxx_TERM, it is at a time where
no more processing should be going on, hence it is not necessary to introduce
a dedicated exit state - this is implicit when unloading the CCID.
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/ccids/ccid3.c | 21 +--------------------
net/dccp/ccids/ccid3.h | 2 --
2 files changed, 1 insertion(+), 22 deletions(-)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -56,7 +56,6 @@ static const char *ccid3_tx_state_name(e
[TFRC_SSTATE_NO_SENT] = "NO_SENT",
[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
[TFRC_SSTATE_FBACK] = "FBACK",
- [TFRC_SSTATE_TERM] = "TERM",
};
return ccid3_state_names[state];
@@ -340,10 +339,6 @@ static int ccid3_hc_tx_send_packet(struc
return (u32)delay / 1000L;
ccid3_hc_tx_update_win_count(hctx, now);
- break;
- case TFRC_SSTATE_TERM:
- DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
- return -EINVAL;
}
/* prepare to send now (add options etc.) */
@@ -379,10 +374,6 @@ static void ccid3_hc_tx_packet_recv(stru
!(dcb->dccpd_type == DCCP_PKT_ACK ||
dcb->dccpd_type == DCCP_PKT_DATAACK))
return;
- /* ... and only in the established state */
- if (hctx->state != TFRC_SSTATE_FBACK &&
- hctx->state != TFRC_SSTATE_NO_FBACK)
- return;
opt_recv = &hctx->options_received;
now = ktime_get_real();
@@ -557,9 +548,7 @@ static void ccid3_hc_tx_exit(struct sock
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
- ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
sk_stop_timer(sk, &hctx->no_feedback_timer);
-
tfrc_tx_hist_purge(&hctx->hist);
}
@@ -618,7 +607,6 @@ static const char *ccid3_rx_state_name(e
static char *ccid3_rx_state_names[] = {
[TFRC_RSTATE_NO_DATA] = "NO_DATA",
[TFRC_RSTATE_DATA] = "DATA",
- [TFRC_RSTATE_TERM] = "TERM",
};
return ccid3_rx_state_names[state];
@@ -644,14 +632,9 @@ static void ccid3_hc_rx_send_feedback(st
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
struct dccp_sock *dp = dccp_sk(sk);
- ktime_t now;
+ ktime_t now = ktime_get_real();
s64 delta = 0;
- if (unlikely(hcrx->state == TFRC_RSTATE_TERM))
- return;
-
- now = ktime_get_real();
-
switch (fbtype) {
case CCID3_FBACK_INITIAL:
hcrx->x_recv = 0;
@@ -855,8 +838,6 @@ static void ccid3_hc_rx_exit(struct sock
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
- ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
-
tfrc_rx_hist_purge(&hcrx->hist);
tfrc_lh_cleanup(&hcrx->li_hist);
}
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -72,7 +72,6 @@ enum ccid3_hc_tx_states {
TFRC_SSTATE_NO_SENT = 1,
TFRC_SSTATE_NO_FBACK,
TFRC_SSTATE_FBACK,
- TFRC_SSTATE_TERM,
};
/** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket
@@ -127,7 +126,6 @@ static inline struct ccid3_hc_tx_sock *c
enum ccid3_hc_rx_states {
TFRC_RSTATE_NO_DATA = 1,
TFRC_RSTATE_DATA,
- TFRC_RSTATE_TERM = 127,
};
/** struct ccid3_hc_rx_sock - CCID3 receiver half-connection socket
--
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