diff options
| -rw-r--r-- | include/linux/srcutiny.h | 1 | ||||
| -rw-r--r-- | include/linux/srcutree.h | 8 | ||||
| -rw-r--r-- | kernel/rcu/srcutree.c | 58 |
3 files changed, 67 insertions, 0 deletions
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h index 51ce25f07930..3bfbd44cb1b3 100644 --- a/include/linux/srcutiny.h +++ b/include/linux/srcutiny.h @@ -103,6 +103,7 @@ static inline void srcu_barrier(struct srcu_struct *ssp) synchronize_srcu(ssp); } +static inline void srcu_expedite_current(struct srcu_struct *ssp) { } #define srcu_check_read_flavor(ssp, read_flavor) do { } while (0) #define srcu_check_read_flavor_force(ssp, read_flavor) do { } while (0) diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 42098e0fa0b7..93ad18acd6d0 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -42,6 +42,8 @@ struct srcu_data { struct timer_list delay_work; /* Delay for CB invoking */ struct work_struct work; /* Context for CB invoking. */ struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */ + struct rcu_head srcu_ec_head; /* For srcu_expedite_current() use. */ + int srcu_ec_state; /* State for srcu_expedite_current(). */ struct srcu_node *mynode; /* Leaf srcu_node. */ unsigned long grpmask; /* Mask for leaf srcu_node */ /* ->srcu_data_have_cbs[]. */ @@ -135,6 +137,11 @@ struct srcu_struct { #define SRCU_STATE_SCAN1 1 #define SRCU_STATE_SCAN2 2 +/* Values for srcu_expedite_current() state (->srcu_ec_state). */ +#define SRCU_EC_IDLE 0 +#define SRCU_EC_PENDING 1 +#define SRCU_EC_REPOST 2 + /* * Values for initializing gp sequence fields. Higher values allow wrap arounds to * occur earlier. @@ -210,6 +217,7 @@ struct srcu_struct { int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp); void synchronize_srcu_expedited(struct srcu_struct *ssp); void srcu_barrier(struct srcu_struct *ssp); +void srcu_expedite_current(struct srcu_struct *ssp); void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); // Converts a per-CPU pointer to an ->srcu_ctrs[] array element to that diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 1ff94b76d91f..38b440b0b0c8 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1688,6 +1688,64 @@ void srcu_barrier(struct srcu_struct *ssp) } EXPORT_SYMBOL_GPL(srcu_barrier); +/* Callback for srcu_expedite_current() usage. */ +static void srcu_expedite_current_cb(struct rcu_head *rhp) +{ + unsigned long flags; + bool needcb = false; + struct srcu_data *sdp = container_of(rhp, struct srcu_data, srcu_ec_head); + + spin_lock_irqsave_sdp_contention(sdp, &flags); + if (sdp->srcu_ec_state == SRCU_EC_IDLE) { + WARN_ON_ONCE(1); + } else if (sdp->srcu_ec_state == SRCU_EC_PENDING) { + sdp->srcu_ec_state = SRCU_EC_IDLE; + } else { + WARN_ON_ONCE(sdp->srcu_ec_state != SRCU_EC_REPOST); + sdp->srcu_ec_state = SRCU_EC_PENDING; + needcb = true; + } + spin_unlock_irqrestore_rcu_node(sdp, flags); + // If needed, requeue ourselves as an expedited SRCU callback. + if (needcb) + __call_srcu(sdp->ssp, &sdp->srcu_ec_head, srcu_expedite_current_cb, false); +} + +/** + * srcu_expedite_current - Expedite the current SRCU grace period + * @ssp: srcu_struct to expedite. + * + * Cause the current SRCU grace period to become expedited. The grace + * period following the current one might also be expedited. If there is + * no current grace period, one might be created. If the current grace + * period is currently sleeping, that sleep will complete before expediting + * will take effect. + */ +void srcu_expedite_current(struct srcu_struct *ssp) +{ + unsigned long flags; + bool needcb = false; + struct srcu_data *sdp; + + migrate_disable(); + sdp = this_cpu_ptr(ssp->sda); + spin_lock_irqsave_sdp_contention(sdp, &flags); + if (sdp->srcu_ec_state == SRCU_EC_IDLE) { + sdp->srcu_ec_state = SRCU_EC_PENDING; + needcb = true; + } else if (sdp->srcu_ec_state == SRCU_EC_PENDING) { + sdp->srcu_ec_state = SRCU_EC_REPOST; + } else { + WARN_ON_ONCE(sdp->srcu_ec_state != SRCU_EC_REPOST); + } + spin_unlock_irqrestore_rcu_node(sdp, flags); + // If needed, queue an expedited SRCU callback. + if (needcb) + __call_srcu(ssp, &sdp->srcu_ec_head, srcu_expedite_current_cb, false); + migrate_enable(); +} +EXPORT_SYMBOL_GPL(srcu_expedite_current); + /** * srcu_batches_completed - return batches completed. * @ssp: srcu_struct on which to report batch completion. |