[PATCH net-next 1/2] net: fix LLS debug_smp_processor_id() warning
From: Eliezer Tamir <hidden>
Date: 2013-06-28 12:59:32
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Our use of sched_clock is OK because we don't mind the side effects of calling it and occasionally waking up on a different CPU. When CONFIG_DEBUG_PREEMPT is on, disable preempt before calling sched_clock() so we don't trigger a debug_smp_processor_id() warning. Reported-by: Cody P Schafer <redacted> Signed-off-by: Eliezer Tamir <redacted> --- include/net/ll_poll.h | 30 +++++++++++++++++++++++++----- 1 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
index 5bf2b3a..6d45e6f 100644
--- a/include/net/ll_poll.h
+++ b/include/net/ll_poll.h@@ -37,20 +37,40 @@ extern unsigned int sysctl_net_ll_poll __read_mostly; #define LL_FLUSH_FAILED -1 #define LL_FLUSH_BUSY -2 -/* we can use sched_clock() because we don't care much about precision +/* a wrapper to make debug_smp_processor_id() happy + * we can use sched_clock() because we don't care much about precision * we only care that the average is bounded - * we don't mind a ~2.5% imprecision so <<10 instead of *1000 + */ +#ifdef CONFIG_DEBUG_PREEMPT +static inline u64 ll_sched_clock(void) +{ + u64 rc; + + preempt_disable_notrace(); + rc = sched_clock(); + preempt_enable_no_resched_notrace(); + + return rc; +} +#else /* CONFIG_DEBUG_PREEMPT */ +static inline u64 ll_sched_clock(void) +{ + return sched_clock(); +} +#endif /* CONFIG_DEBUG_PREEMPT */ + +/* 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) { - return ((u64)ACCESS_ONCE(sk->sk_ll_usec) << 10) + sched_clock(); + return ((u64)ACCESS_ONCE(sk->sk_ll_usec) << 10) + ll_sched_clock(); } /* in poll/select we use the global sysctl_net_ll_poll value */ static inline u64 ll_end_time(void) { - return ((u64)ACCESS_ONCE(sysctl_net_ll_poll) << 10) + sched_clock(); + return ((u64)ACCESS_ONCE(sysctl_net_ll_poll) << 10) + ll_sched_clock(); } static inline bool sk_valid_ll(struct sock *sk)
@@ -61,7 +81,7 @@ static inline bool sk_valid_ll(struct sock *sk) static inline bool can_poll_ll(u64 end_time) { - return !time_after64(sched_clock(), end_time); + return !time_after64(ll_sched_clock(), end_time); } /* when used in sock_poll() nonblock is known at compile time to be true