Preparation to fit TX list locking
PATCH 16/29 Preparation to fit TX list locking
This patch prepares adding TX history locking by changing all functions which return a reference to a TX history object:
1) removal of dccp_tx_hist_head - nowhere used in the code;
2) change dccp_tx_hist_find_entry - the sole use is to look up a timestamp for an Ack-ed packet; and then do garbage-collection.
The latter function is changed to return the desired timestamp instead of a history object reference.
Not returning object references is necessary, since otherwise lists could not be garbage-collected (or would have to use atomic reference counts).
Furthermore, the garbage-collection is now integrated into (2), since it requires first a read access and then a write access at the same place in the list: giving up the lock here would permit race condition.
Signed-off-by Gerrit Renker <[email protected]>
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
--- net/dccp/ccids/ccid3.c | 18 +++++++----------- net/dccp/ccids/lib/packet_history.c | 27 +++++++++++++++++++++------ net/dccp/ccids/lib/packet_history.h | 16 ++-------------- 3 files changed, 30 insertions(+), 31 deletions(-)
net/dccp/ccids/ccid3.c +7 -11
@@ -421,10 +421,9 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) {struct ccid3_hc_tx_sock *hctx =ccid3_hc_tx_sk (sk);struct ccid3_options_received *opt_recv; -struct dccp_tx_hist_entry *packet; -struct timeval now; +struct timeval now, t_send;unsigned long t_nfb; -u32 pinv, r_sample; +u32 pinv, r_sample, rc;BUG_ON (hctx =NULL );
@@ -440,10 +439,10 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)default :return ; } -/* get packet from history to look up t_recvdata */ - packet =dccp_tx_hist_find_entry (&hctx->ccid3hctx_hist, -DCCP_SKB_CB (skb)->dccpd_ack_seq); -if (unlikely (packet =NULL )) { +/* look up t_recvdata in packet history */ + rc =dccp_tx_hist_get_send_time (ccid3_tx_hist, &hctx->ccid3hctx_hist, +DCCP_SKB_CB (skb)->dccpd_ack_seq, &t_send); +if (unlikely (!rc)) { DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist in history!\n", dccp_role(sk), sk, (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
@@ -466,7 +465,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)* R_sample = (t_now - t_recvdata) - t_elapsed */ skb_get_timestamp (skb, &now); - r_sample =dccp_sample_rtt (sk, &now, &packet->dccphtx_tstamp); + r_sample =dccp_sample_rtt (sk, &now, &t_send);/* * Update RTT estimate (honours RTT from SYN exchange):
@@ -523,9 +522,6 @@ done_computing_x:/* unschedule no feedback timer */ sk_stop_timer (sk, &hctx->ccid3hctx_no_feedback_timer); -/* remove all packets older than the one acked from history */ -dccp_tx_hist_purge_older (ccid3_tx_hist, - &hctx->ccid3hctx_hist, packet);/* * As we have calculated new ipi, delta, t_nom it is possible * that we now can send a packet, so wake up dccp_wait_for_ccid
net/dccp/ccids/lib/packet_history.c +21 -6
@@ -85,21 +85,36 @@ void dccp_tx_hist_delete(struct dccp_tx_hist *hist)EXPORT_SYMBOL_GPL (dccp_tx_hist_delete); -struct dccp_tx_hist_entry * -dccp_tx_hist_find_entry (const struct list_head *list,const u64 seq) +/** +* dccp_tx_hist_get_send_time - Retrieve timestamp of sent packet +* +* @hist: history slab associated with TX history +* @list: TX history list head +* @seq: 48-bit sequence number of packet in question +* @t_send: timestamp to be returned +* Returns 1 on success and then garbage-collects all older entries. +*/ +int dccp_tx_hist_get_send_time (struct dccp_tx_hist *hist, +struct list_head *list,u64 seq, +struct timeval *t_send) { -struct dccp_tx_hist_entry *packet =NULL , *entry; +struct dccp_tx_hist_entry *entry; +int found =0 ;list_for_each_entry (entry, list, dccphtx_node)if (entry->dccphtx_seqno = seq) { - packet = entry; + found =1 ; + *t_send = entry->dccphtx_tstamp;break ; } -return packet; +if (found) +dccp_tx_hist_purge_older (hist, list, entry); + +return found; } -EXPORT_SYMBOL_GPL (dccp_tx_hist_find_entry); +EXPORT_SYMBOL_GPL (dccp_tx_hist_get_send_time);void dccp_tx_hist_purge (struct dccp_tx_hist *hist,struct list_head *list) {
net/dccp/ccids/lib/packet_history.h +2 -14
@@ -80,20 +80,8 @@ static inline struct dccp_tx_hist_entry *return entry; } -static inline struct dccp_tx_hist_entry * -dccp_tx_hist_head (struct list_head *list) -{ -struct dccp_tx_hist_entry *head =NULL ; - -if (!list_empty (list)) - head = list_entry(list->next, struct dccp_tx_hist_entry, - dccphtx_node); -return head; -} - -extern struct dccp_tx_hist_entry * -dccp_tx_hist_find_entry (const struct list_head *list, -const u64 seq); +extern int dccp_tx_hist_get_send_time (struct dccp_tx_hist *,struct list_head *, +u64 seq,struct timeval *t_send);static inline void dccp_tx_hist_add_entry (struct list_head *list,struct dccp_tx_hist_entry *entry)
Signature · 1 line
1.5.0.6