Commit fe84f4140f0d24deca8591e38926b95cfd097e62
Committed by
David S. Miller
David S. Miller
1 parent
de7fe7874d
Exists in
master
and in
20 other branches
dccp: Return-value convention of hc_tx_send_packet()
This patch reorganises the return value convention of the CCID TX sending function, to permit more flexible schemes, as required by subsequent patches. Currently the convention is * values < 0 mean error, * a value == 0 means "send now", and * a value x > 0 means "send in x milliseconds". The patch provides symbolic constants and a function to interpret return values. In addition, it caps the maximum positive return value to 0xFFFF milliseconds, corresponding to 65.535 seconds. This is possible since in CCID-3/4 the maximum possible inter-packet gap is fixed at t_mbi = 64 sec. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Showing 2 changed files with 37 additions and 9 deletions Side-by-side Diff
net/dccp/ccid.h
| ... | ... | @@ -134,13 +134,41 @@ |
| 134 | 134 | extern void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk); |
| 135 | 135 | extern void ccid_hc_tx_delete(struct ccid *ccid, struct sock *sk); |
| 136 | 136 | |
| 137 | +/* | |
| 138 | + * Congestion control of queued data packets via CCID decision. | |
| 139 | + * | |
| 140 | + * The TX CCID performs its congestion-control by indicating whether and when a | |
| 141 | + * queued packet may be sent, using the return code of ccid_hc_tx_send_packet(). | |
| 142 | + * The following modes are supported via the symbolic constants below: | |
| 143 | + * - timer-based pacing (CCID returns a delay value in milliseconds); | |
| 144 | + * - autonomous dequeueing (CCID internally schedules dccps_xmitlet). | |
| 145 | + */ | |
| 146 | + | |
| 147 | +enum ccid_dequeueing_decision { | |
| 148 | + CCID_PACKET_SEND_AT_ONCE = 0x00000, /* "green light": no delay */ | |
| 149 | + CCID_PACKET_DELAY_MAX = 0x0FFFF, /* maximum delay in msecs */ | |
| 150 | + CCID_PACKET_DELAY = 0x10000, /* CCID msec-delay mode */ | |
| 151 | + CCID_PACKET_WILL_DEQUEUE_LATER = 0x20000, /* CCID autonomous mode */ | |
| 152 | + CCID_PACKET_ERR = 0xF0000, /* error condition */ | |
| 153 | +}; | |
| 154 | + | |
| 155 | +static inline int ccid_packet_dequeue_eval(const int return_code) | |
| 156 | +{ | |
| 157 | + if (return_code < 0) | |
| 158 | + return CCID_PACKET_ERR; | |
| 159 | + if (return_code == 0) | |
| 160 | + return CCID_PACKET_SEND_AT_ONCE; | |
| 161 | + if (return_code <= CCID_PACKET_DELAY_MAX) | |
| 162 | + return CCID_PACKET_DELAY; | |
| 163 | + return return_code; | |
| 164 | +} | |
| 165 | + | |
| 137 | 166 | static inline int ccid_hc_tx_send_packet(struct ccid *ccid, struct sock *sk, |
| 138 | 167 | struct sk_buff *skb) |
| 139 | 168 | { |
| 140 | - int rc = 0; | |
| 141 | 169 | if (ccid->ccid_ops->ccid_hc_tx_send_packet != NULL) |
| 142 | - rc = ccid->ccid_ops->ccid_hc_tx_send_packet(sk, skb); | |
| 143 | - return rc; | |
| 170 | + return ccid->ccid_ops->ccid_hc_tx_send_packet(sk, skb); | |
| 171 | + return CCID_PACKET_SEND_AT_ONCE; | |
| 144 | 172 | } |
| 145 | 173 | |
| 146 | 174 | static inline void ccid_hc_tx_packet_sent(struct ccid *ccid, struct sock *sk, |
net/dccp/ccids/ccid3.c
| ... | ... | @@ -268,11 +268,11 @@ |
| 268 | 268 | sock_put(sk); |
| 269 | 269 | } |
| 270 | 270 | |
| 271 | -/* | |
| 272 | - * returns | |
| 273 | - * > 0: delay (in msecs) that should pass before actually sending | |
| 274 | - * = 0: can send immediately | |
| 275 | - * < 0: error condition; do not send packet | |
| 271 | +/** | |
| 272 | + * ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets | |
| 273 | + * @skb: next packet candidate to send on @sk | |
| 274 | + * This function uses the convention of ccid_packet_dequeue_eval() and | |
| 275 | + * returns a millisecond-delay value between 0 and t_mbi = 64000 msec. | |
| 276 | 276 | */ |
| 277 | 277 | static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) |
| 278 | 278 | { |
| ... | ... | @@ -348,7 +348,7 @@ |
| 348 | 348 | |
| 349 | 349 | /* set the nominal send time for the next following packet */ |
| 350 | 350 | hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi); |
| 351 | - return 0; | |
| 351 | + return CCID_PACKET_SEND_AT_ONCE; | |
| 352 | 352 | } |
| 353 | 353 | |
| 354 | 354 | static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len) |