diff options
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 13 | ||||
| -rw-r--r-- | net/dccp/dccp.h | 5 | ||||
| -rw-r--r-- | net/dccp/timer.c | 3 |
3 files changed, 18 insertions, 3 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 0d406f82e43..f566eb76aeb 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -869,6 +869,19 @@ MODULE_PARM_DESC(ccid3_debug, "Enable debug messages"); static __init int ccid3_module_init(void) { + struct timespec tp; + + /* + * Without a fine-grained clock resolution, RTTs/X_recv are not sampled + * correctly and feedback is sent either too early or too late. + */ + hrtimer_get_res(CLOCK_MONOTONIC, &tp); + if (tp.tv_sec || tp.tv_nsec > DCCP_TIME_RESOLUTION * NSEC_PER_USEC) { + printk(KERN_ERR "%s: Timer too coarse (%ld usec), need %u-usec" + " resolution - check your clocksource.\n", __func__, + tp.tv_nsec/NSEC_PER_USEC, DCCP_TIME_RESOLUTION); + return -ESOCKTNOSUPPORT; + } return ccid_register(&ccid3); } module_init(ccid3_module_init); diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 1585fa26488..b63a82ccb2b 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -86,10 +86,13 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo); */ #define DCCP_RTO_MAX ((unsigned)(64 * HZ)) +/* DCCP base time resolution - 10 microseconds (RFC 4340, 13.1 ... 13.3) */ +#define DCCP_TIME_RESOLUTION 10 + /* * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4 */ -#define DCCP_SANE_RTT_MIN 100 +#define DCCP_SANE_RTT_MIN (10 * DCCP_TIME_RESOLUTION) #define DCCP_FALLBACK_RTT (USEC_PER_SEC / 5) #define DCCP_SANE_RTT_MAX (3 * USEC_PER_SEC) diff --git a/net/dccp/timer.c b/net/dccp/timer.c index e02d5a94f4c..16359e29e7f 100644 --- a/net/dccp/timer.c +++ b/net/dccp/timer.c @@ -281,8 +281,7 @@ u32 dccp_timestamp(void) { s64 delta = ktime_us_delta(ktime_get_real(), dccp_timestamp_seed); - do_div(delta, 10); - return delta; + return div_u64(delta, DCCP_TIME_RESOLUTION); } EXPORT_SYMBOL_GPL(dccp_timestamp); |