diff options
| -rw-r--r-- | include/linux/rcupdate.h | 13 | ||||
| -rw-r--r-- | kernel/rcupdate.c | 11 |
2 files changed, 12 insertions, 12 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 3f6c5e4cb92c..4d747433916b 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -87,9 +87,7 @@ static inline int rcu_batch_after(long a, long b) struct rcu_data { /* 1) quiescent state handling : */ long quiescbatch; /* Batch # for grace period */ - long qsctr; /* User-mode/idle loop etc. */ - long last_qsctr; /* value of qsctr at beginning */ - /* of rcu grace period */ + int passed_quiesc; /* User-mode/idle loop etc. */ int qs_pending; /* core waits for quiesc state */ /* 2) batch handling */ @@ -109,17 +107,20 @@ extern struct rcu_ctrlblk rcu_ctrlblk; extern struct rcu_ctrlblk rcu_bh_ctrlblk; /* - * Increment the quiscent state counter. + * Increment the quiescent state counter. + * The counter is a bit degenerated: We do not need to know + * how many quiescent states passed, just if there was at least + * one since the start of the grace period. Thus just a flag. */ static inline void rcu_qsctr_inc(int cpu) { struct rcu_data *rdp = &per_cpu(rcu_data, cpu); - rdp->qsctr++; + rdp->passed_quiesc = 1; } static inline void rcu_bh_qsctr_inc(int cpu) { struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); - rdp->qsctr++; + rdp->passed_quiesc = 1; } static inline int __rcu_pending(struct rcu_ctrlblk *rcp, diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index ebe7e5d96b35..f0ae3c3c013e 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -219,9 +219,9 @@ static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, struct rcu_state *rsp, struct rcu_data *rdp) { if (rdp->quiescbatch != rcp->cur) { - /* new grace period: record qsctr value. */ + /* start new grace period: */ rdp->qs_pending = 1; - rdp->last_qsctr = rdp->qsctr; + rdp->passed_quiesc = 0; rdp->quiescbatch = rcp->cur; return; } @@ -234,11 +234,10 @@ static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, return; /* - * Races with local timer interrupt - in the worst case - * we may miss one quiescent state of that CPU. That is - * tolerable. So no need to disable interrupts. + * Was there a quiescent state since the beginning of the grace + * period? If no, then exit and wait for the next call. */ - if (rdp->qsctr == rdp->last_qsctr) + if (!rdp->passed_quiesc) return; rdp->qs_pending = 0; |