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| author | Eliezer Tamir <eliezer.tamir@linux.intel.com> | 2013-07-02 22:22:47 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-07-03 00:53:53 +0200 |
| commit | 1bc2774d866444c5b316fd1dc2b782f20c762cf4 (patch) | |
| tree | dfadce12c9f45c80cd372b27456151be000c8aee /include/net | |
| parent | nlmon: use standard rtnetlink link api for add/del devices (diff) | |
| download | linux-1bc2774d866444c5b316fd1dc2b782f20c762cf4.tar.xz linux-1bc2774d866444c5b316fd1dc2b782f20c762cf4.zip | |
net: convert lls to use time_in_range()
Time in range will fail safely if we move to a different cpu with an
extremely large clock skew.
Add time_in_range64() and convert lls to use it.
changelog:
v2
- fixed double call to sched_clock in can_poll_ll
- fixed checkpatchisms
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/ll_poll.h | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h index 6c06f7c0a22d..b76f004f18a9 100644 --- a/include/net/ll_poll.h +++ b/include/net/ll_poll.h @@ -67,19 +67,23 @@ static inline u64 ll_sched_clock(void) /* we don't mind a ~2.5% imprecision so <<10 instead of *1000 * sk->sk_ll_usec is a u_int so this can't overflow */ -static inline u64 ll_sk_end_time(struct sock *sk) +static inline u64 ll_sk_run_time(struct sock *sk) { - return ((u64)ACCESS_ONCE(sk->sk_ll_usec) << 10) + ll_sched_clock(); + return (u64)ACCESS_ONCE(sk->sk_ll_usec) << 10; } /* in poll/select we use the global sysctl_net_ll_poll value * only call sched_clock() if enabled */ -static inline u64 ll_end_time(void) +static inline u64 ll_run_time(void) { - u64 end_time = ACCESS_ONCE(sysctl_net_ll_poll); + return (u64)ACCESS_ONCE(sysctl_net_ll_poll) << 10; +} - return end_time ? (end_time << 10) + ll_sched_clock() : 0; +/* if flag is not set we don't need to know the time */ +static inline u64 ll_start_time(unsigned int flag) +{ + return flag ? ll_sched_clock() : 0; } static inline bool sk_valid_ll(struct sock *sk) @@ -88,9 +92,12 @@ static inline bool sk_valid_ll(struct sock *sk) !need_resched() && !signal_pending(current); } -static inline bool can_poll_ll(u64 end_time) +/* careful! time_in_range64 will evaluate now twice */ +static inline bool can_poll_ll(u64 start_time, u64 run_time) { - return !time_after64(ll_sched_clock(), end_time); + u64 now = ll_sched_clock(); + + return time_in_range64(now, start_time, start_time + run_time); } /* when used in sock_poll() nonblock is known at compile time to be true @@ -98,7 +105,8 @@ static inline bool can_poll_ll(u64 end_time) */ static inline bool sk_poll_ll(struct sock *sk, int nonblock) { - u64 end_time = nonblock ? 0 : ll_sk_end_time(sk); + u64 start_time = ll_start_time(!nonblock); + u64 run_time = ll_sk_run_time(sk); const struct net_device_ops *ops; struct napi_struct *napi; int rc = false; @@ -129,7 +137,7 @@ static inline bool sk_poll_ll(struct sock *sk, int nonblock) LINUX_MIB_LOWLATENCYRXPACKETS, rc); } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) && - can_poll_ll(end_time)); + can_poll_ll(start_time, run_time)); rc = !skb_queue_empty(&sk->sk_receive_queue); out: |