diff options
Diffstat (limited to 'include/linux/rcu_segcblist.h')
| -rw-r--r-- | include/linux/rcu_segcblist.h | 42 |
1 files changed, 38 insertions, 4 deletions
diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h index 74b1e7243955..ced8f313fd05 100644 --- a/include/linux/rcu_segcblist.h +++ b/include/linux/rcu_segcblist.h @@ -402,6 +402,37 @@ static inline void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, } /* + * Entrain the specified callback onto the specified rcu_segcblist at + * the end of the last non-empty segment. If the entire rcu_segcblist + * is empty, make no change, but return false. + * + * This is intended for use by rcu_barrier()-like primitives, -not- + * for normal grace-period use. IMPORTANT: The callback you enqueue + * will wait for all prior callbacks, NOT necessarily for a grace + * period. You have been warned. + */ +static inline bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, + struct rcu_head *rhp, bool lazy) +{ + int i; + + if (rcu_segcblist_n_cbs(rsclp) == 0) + return false; + WRITE_ONCE(rsclp->len, rsclp->len + 1); + if (lazy) + rsclp->len_lazy++; + smp_mb(); /* Ensure counts are updated before callback is entrained. */ + rhp->next = NULL; + for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) + if (rsclp->tails[i] != rsclp->tails[i - 1]) + break; + *rsclp->tails[i] = rhp; + for (; i <= RCU_NEXT_TAIL; i++) + rsclp->tails[i] = &rhp->next; + return true; +} + +/* * Extract only the counts from the specified rcu_segcblist structure, * and place them in the specified rcu_cblist structure. This function * supports both callback orphaning and invocation, hence the separation @@ -537,7 +568,8 @@ static inline void rcu_segcblist_advance(struct rcu_segcblist *rsclp, int i, j; WARN_ON_ONCE(!rcu_segcblist_is_enabled(rsclp)); - WARN_ON_ONCE(rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL)); + if (rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL)) + return; /* * Find all callbacks whose ->gp_seq numbers indicate that they @@ -582,8 +614,9 @@ static inline void rcu_segcblist_advance(struct rcu_segcblist *rsclp, * them to complete at the end of the earlier grace period. * * This function operates on an rcu_segcblist structure, and also the - * grace-period sequence number at which new callbacks would become - * ready to invoke. + * grace-period sequence number seq at which new callbacks would become + * ready to invoke. Returns true if there are callbacks that won't be + * ready to invoke until seq, false otherwise. */ static inline bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq) @@ -591,7 +624,8 @@ static inline bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, int i; WARN_ON_ONCE(!rcu_segcblist_is_enabled(rsclp)); - WARN_ON_ONCE(rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL)); + if (rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL)) + return false; /* * Find the segment preceding the oldest segment of callbacks |