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>
diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
index 6c06f7c..b76f004 100644
--- a/include/net/ll_poll.h
+++ b/include/net/ll_poll.h
@@ -67,19 +67,23 @@
/* 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 @@
!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 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 @@
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: