diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutree.c | 72 | ||||
| -rw-r--r-- | kernel/rcutree.h | 31 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 23 |
3 files changed, 77 insertions, 49 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index f85b6842d1e..53a5ef0ca91 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -81,24 +81,29 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); -extern long rcu_batches_completed_sched(void); -static struct rcu_node *rcu_get_root(struct rcu_state *rsp); -static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, - struct rcu_node *rnp, unsigned long flags); -static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags); +/* Forward declarations for rcutree_plugin.h */ +static inline void rcu_bootup_announce(void); +long rcu_batches_completed(void); +static void rcu_preempt_note_context_switch(int cpu); +static int rcu_preempted_readers(struct rcu_node *rnp); +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR +static void rcu_print_task_stall(struct rcu_node *rnp); +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ +static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); #ifdef CONFIG_HOTPLUG_CPU -static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp); +static void rcu_preempt_offline_tasks(struct rcu_state *rsp, + struct rcu_node *rnp, + struct rcu_data *rdp); +static void rcu_preempt_offline_cpu(int cpu); #endif /* #ifdef CONFIG_HOTPLUG_CPU */ -static void __rcu_process_callbacks(struct rcu_state *rsp, - struct rcu_data *rdp); -static void __call_rcu(struct rcu_head *head, - void (*func)(struct rcu_head *rcu), - struct rcu_state *rsp); -static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp); -static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp, - int preemptable); +static void rcu_preempt_check_callbacks(int cpu); +static void rcu_preempt_process_callbacks(void); +void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); +static int rcu_preempt_pending(int cpu); +static int rcu_preempt_needs_cpu(int cpu); +static void __cpuinit rcu_preempt_init_percpu_data(int cpu); +static void __init __rcu_init_preempt(void); -#include "rcutree_plugin.h" /* * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s @@ -377,7 +382,7 @@ static long dyntick_recall_completed(struct rcu_state *rsp) /* * Snapshot the specified CPU's dynticks counter so that we can later * credit them with an implicit quiescent state. Return 1 if this CPU - * is already in a quiescent state courtesy of dynticks idle mode. + * is in dynticks idle mode, which is an extended quiescent state. */ static int dyntick_save_progress_counter(struct rcu_data *rdp) { @@ -624,9 +629,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) note_new_gpnum(rsp, rdp); /* - * Because we are first, we know that all our callbacks will - * be covered by this upcoming grace period, even the ones - * that were registered arbitrarily recently. + * Because this CPU just now started the new grace period, we know + * that all of its callbacks will be covered by this upcoming grace + * period, even the ones that were registered arbitrarily recently. + * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL. + * + * Other CPUs cannot be sure exactly when the grace period started. + * Therefore, their recently registered callbacks must pass through + * an additional RCU_NEXT_READY stage, so that they will be handled + * by the next RCU grace period. */ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; @@ -886,7 +897,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) /* * Move callbacks from the outgoing CPU to the running CPU. - * Note that the outgoing CPU is now quiscent, so it is now + * Note that the outgoing CPU is now quiescent, so it is now * (uncharacteristically) safe to access its rcu_data structure. * Note also that we must carefully retain the order of the * outgoing CPU's callbacks in order for rcu_barrier() to work @@ -1577,25 +1588,6 @@ do { \ } \ } while (0) -#ifdef CONFIG_TREE_PREEMPT_RCU - -void __init __rcu_init_preempt(void) -{ - int i; /* All used by RCU_INIT_FLAVOR(). */ - int j; - struct rcu_node *rnp; - - RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data); -} - -#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ - -void __init __rcu_init_preempt(void) -{ -} - -#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ - void __init __rcu_init(void) { int i; /* All used by RCU_INIT_FLAVOR(). */ @@ -1612,6 +1604,8 @@ void __init __rcu_init(void) open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); } +#include "rcutree_plugin.h" + module_param(blimit, int, 0); module_param(qhimark, int, 0); module_param(qlowmark, int, 0); diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 9aa8c8a160d..a48d11f37b4 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -79,15 +79,21 @@ struct rcu_dynticks { * Definition for node within the RCU grace-period-detection hierarchy. */ struct rcu_node { - spinlock_t lock; + spinlock_t lock; /* Root rcu_node's lock protects some */ + /* rcu_state fields as well as following. */ long gpnum; /* Current grace period for this node. */ /* This will either be equal to or one */ /* behind the root rcu_node's gpnum. */ unsigned long qsmask; /* CPUs or groups that need to switch in */ /* order for current grace period to proceed.*/ + /* In leaf rcu_node, each bit corresponds to */ + /* an rcu_data structure, otherwise, each */ + /* bit corresponds to a child rcu_node */ + /* structure. */ unsigned long qsmaskinit; /* Per-GP initialization for qsmask. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ + /* Only one bit will be set in this mask. */ int grplo; /* lowest-numbered CPU or group here. */ int grphi; /* highest-numbered CPU or group here. */ u8 grpnum; /* CPU/group number for next level up. */ @@ -95,6 +101,9 @@ struct rcu_node { struct rcu_node *parent; struct list_head blocked_tasks[2]; /* Tasks blocked in RCU read-side critsect. */ + /* Grace period number (->gpnum) x blocked */ + /* by tasks on the (x & 0x1) element of the */ + /* blocked_tasks[] array. */ } ____cacheline_internodealigned_in_smp; /* Index values for nxttail array in struct rcu_data. */ @@ -126,19 +135,22 @@ struct rcu_data { * Any of the partitions might be empty, in which case the * pointer to that partition will be equal to the pointer for * the following partition. When the list is empty, all of - * the nxttail elements point to nxtlist, which is NULL. + * the nxttail elements point to the ->nxtlist pointer itself, + * which in that case is NULL. * - * [*nxttail[RCU_NEXT_READY_TAIL], NULL = *nxttail[RCU_NEXT_TAIL]): - * Entries that might have arrived after current GP ended - * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): - * Entries known to have arrived before current GP ended - * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): - * Entries that batch # <= ->completed - 1: waiting for current GP * [nxtlist, *nxttail[RCU_DONE_TAIL]): * Entries that batch # <= ->completed * The grace period for these entries has completed, and * the other grace-period-completed entries may be moved * here temporarily in rcu_process_callbacks(). + * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): + * Entries that batch # <= ->completed - 1: waiting for current GP + * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): + * Entries known to have arrived before current GP ended + * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): + * Entries that might have arrived after current GP ended + * Note that the value of *nxttail[RCU_NEXT_TAIL] will + * always be NULL, as this is the end of the list. */ struct rcu_head *nxtlist; struct rcu_head **nxttail[RCU_NEXT_SIZE]; @@ -216,6 +228,9 @@ struct rcu_state { /* Force QS state. */ long gpnum; /* Current gp number. */ long completed; /* # of last completed gp. */ + + /* End of fields guarded by root rcu_node's lock. */ + spinlock_t onofflock; /* exclude on/offline and */ /* starting new GP. */ spinlock_t fqslock; /* Only one task forcing */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 8ff1ba7b3c4..65250219ab6 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -419,6 +419,18 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) } /* + * Initialize preemptable RCU's state structures. + */ +static void __init __rcu_init_preempt(void) +{ + int i; /* All used by RCU_INIT_FLAVOR(). */ + int j; + struct rcu_node *rnp; + + RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data); +} + +/* * Check for a task exiting while in a preemptable-RCU read-side * critical section, clean up if so. No need to issue warnings, * as debug_check_no_locks_held() already does this if lockdep @@ -518,7 +530,7 @@ static void rcu_preempt_offline_cpu(int cpu) * Because preemptable RCU does not exist, it never has any callbacks * to check. */ -void rcu_preempt_check_callbacks(int cpu) +static void rcu_preempt_check_callbacks(int cpu) { } @@ -526,7 +538,7 @@ void rcu_preempt_check_callbacks(int cpu) * Because preemptable RCU does not exist, it never has any callbacks * to process. */ -void rcu_preempt_process_callbacks(void) +static void rcu_preempt_process_callbacks(void) { } @@ -563,4 +575,11 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) { } +/* + * Because preemptable RCU does not exist, it need not be initialized. + */ +static void __init __rcu_init_preempt(void) +{ +} + #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ |