diff options
| -rw-r--r-- | net/dccp/dccp.h | 10 | ||||
| -rw-r--r-- | net/dccp/input.c | 40 |
2 files changed, 48 insertions, 2 deletions
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 292f18ef4f6..d8ad27bfe01 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -71,11 +71,15 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo); /* RFC 1122, 4.2.3.1 initial RTO value */ #define DCCP_TIMEOUT_INIT ((unsigned)(3 * HZ)) +#define DCCP_RTO_MAX ((unsigned)(120 * HZ)) /* FIXME: using TCP value */ + +/* bounds for sampled RTT values from packet exchanges (in usec) */ +#define DCCP_SANE_RTT_MIN 100 +#define DCCP_SANE_RTT_MAX (4 * USEC_PER_SEC) + /* Maximal interval between probes for local resources. */ #define DCCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ / 2U)) -#define DCCP_RTO_MAX ((unsigned)(120 * HZ)) /* FIXME: using TCP value */ - /* sysctl variables for DCCP */ extern int sysctl_dccp_request_retries; extern int sysctl_dccp_retries1; @@ -292,6 +296,8 @@ extern int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, extern int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code); extern void dccp_send_close(struct sock *sk, const int active); extern int dccp_invalid_packet(struct sk_buff *skb); +extern u32 dccp_sample_rtt(struct sock *sk, struct timeval *t_recv, + struct timeval *t_history); static inline int dccp_bad_service_code(const struct sock *sk, const __be32 service) diff --git a/net/dccp/input.c b/net/dccp/input.c index a1900157e2d..bd578c87b2e 100644 --- a/net/dccp/input.c +++ b/net/dccp/input.c @@ -577,3 +577,43 @@ discard: } EXPORT_SYMBOL_GPL(dccp_rcv_state_process); + +/** + * dccp_sample_rtt - Sample RTT from packet exchange + * + * @sk: connected dccp_sock + * @t_recv: receive timestamp of packet with timestamp echo + * @t_hist: packet history timestamp or NULL + */ +u32 dccp_sample_rtt(struct sock *sk, struct timeval *t_recv, + struct timeval *t_hist) +{ + struct dccp_sock *dp = dccp_sk(sk); + struct dccp_options_received *or = &dp->dccps_options_received; + suseconds_t delta; + + if (t_hist == NULL) { + if (!or->dccpor_timestamp_echo) { + DCCP_WARN("packet without timestamp echo\n"); + return DCCP_SANE_RTT_MAX; + } + timeval_sub_usecs(t_recv, or->dccpor_timestamp_echo * 10); + delta = timeval_usecs(t_recv); + } else + delta = timeval_delta(t_recv, t_hist); + + delta -= or->dccpor_elapsed_time * 10; /* either set or 0 */ + + if (unlikely(delta <= 0)) { + DCCP_WARN("unusable RTT sample %ld, using min\n", (long)delta); + return DCCP_SANE_RTT_MIN; + } + if (unlikely(delta - (suseconds_t)DCCP_SANE_RTT_MAX > 0)) { + DCCP_WARN("RTT sample %ld too large, using max\n", (long)delta); + return DCCP_SANE_RTT_MAX; + } + + return delta; +} + +EXPORT_SYMBOL_GPL(dccp_sample_rtt); |