diff options
Diffstat (limited to 'kernel/rcupdate.c')
| -rw-r--r-- | kernel/rcupdate.c | 135 |
1 files changed, 72 insertions, 63 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 48d3bce465b88..0cf8146bd5859 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -35,6 +35,7 @@ #include <linux/init.h> #include <linux/spinlock.h> #include <linux/smp.h> +#include <linux/rcupdate.h> #include <linux/interrupt.h> #include <linux/sched.h> #include <asm/atomic.h> @@ -45,26 +46,21 @@ #include <linux/percpu.h> #include <linux/notifier.h> #include <linux/rcupdate.h> -#include <linux/rcuref.h> #include <linux/cpu.h> /* Definition for rcupdate control block. */ -struct rcu_ctrlblk rcu_ctrlblk = - { .cur = -300, .completed = -300 }; -struct rcu_ctrlblk rcu_bh_ctrlblk = - { .cur = -300, .completed = -300 }; - -/* Bookkeeping of the progress of the grace period */ -struct rcu_state { - spinlock_t lock; /* Guard this struct and writes to rcu_ctrlblk */ - cpumask_t cpumask; /* CPUs that need to switch in order */ - /* for current batch to proceed. */ +struct rcu_ctrlblk rcu_ctrlblk = { + .cur = -300, + .completed = -300, + .lock = SPIN_LOCK_UNLOCKED, + .cpumask = CPU_MASK_NONE, +}; +struct rcu_ctrlblk rcu_bh_ctrlblk = { + .cur = -300, + .completed = -300, + .lock = SPIN_LOCK_UNLOCKED, + .cpumask = CPU_MASK_NONE, }; - -static struct rcu_state rcu_state ____cacheline_maxaligned_in_smp = - {.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE }; -static struct rcu_state rcu_bh_state ____cacheline_maxaligned_in_smp = - {.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE }; DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L }; DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; @@ -73,19 +69,6 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL}; static int maxbatch = 10000; -#ifndef __HAVE_ARCH_CMPXCHG -/* - * We use an array of spinlocks for the rcurefs -- similar to ones in sparc - * 32 bit atomic_t implementations, and a hash function similar to that - * for our refcounting needs. - * Can't help multiprocessors which donot have cmpxchg :( - */ - -spinlock_t __rcuref_hash[RCUREF_HASH_SIZE] = { - [0 ... (RCUREF_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED -}; -#endif - /** * call_rcu - Queue an RCU callback for invocation after a grace period. * @head: structure to be used for queueing the RCU updates. @@ -233,13 +216,13 @@ static void rcu_do_batch(struct rcu_data *rdp) * This is done by rcu_start_batch. The start is not broadcasted to * all cpus, they must pick this up by comparing rcp->cur with * rdp->quiescbatch. All cpus are recorded in the - * rcu_state.cpumask bitmap. + * rcu_ctrlblk.cpumask bitmap. * - All cpus must go through a quiescent state. * Since the start of the grace period is not broadcasted, at least two * calls to rcu_check_quiescent_state are required: * The first call just notices that a new grace period is running. The * following calls check if there was a quiescent state since the beginning - * of the grace period. If so, it updates rcu_state.cpumask. If + * of the grace period. If so, it updates rcu_ctrlblk.cpumask. If * the bitmap is empty, then the grace period is completed. * rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace * period (if necessary). @@ -247,14 +230,10 @@ static void rcu_do_batch(struct rcu_data *rdp) /* * Register a new batch of callbacks, and start it up if there is currently no * active batch and the batch to be registered has not already occurred. - * Caller must hold rcu_state.lock. + * Caller must hold rcu_ctrlblk.lock. */ -static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp, - int next_pending) +static void rcu_start_batch(struct rcu_ctrlblk *rcp) { - if (next_pending) - rcp->next_pending = 1; - if (rcp->next_pending && rcp->completed == rcp->cur) { rcp->next_pending = 0; @@ -268,11 +247,11 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp, /* * Accessing nohz_cpu_mask before incrementing rcp->cur needs a * Barrier Otherwise it can cause tickless idle CPUs to be - * included in rsp->cpumask, which will extend graceperiods + * included in rcp->cpumask, which will extend graceperiods * unnecessarily. */ smp_mb(); - cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask); + cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask); } } @@ -282,13 +261,13 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp, * Clear it from the cpu mask and complete the grace period if it was the last * cpu. Start another grace period if someone has further entries pending */ -static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp, struct rcu_state *rsp) +static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp) { - cpu_clear(cpu, rsp->cpumask); - if (cpus_empty(rsp->cpumask)) { + cpu_clear(cpu, rcp->cpumask); + if (cpus_empty(rcp->cpumask)) { /* batch completed ! */ rcp->completed = rcp->cur; - rcu_start_batch(rcp, rsp, 0); + rcu_start_batch(rcp); } } @@ -298,7 +277,7 @@ static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp, struct rcu_state *rsp) * quiescent cycle, then indicate that it has done so. */ static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, - struct rcu_state *rsp, struct rcu_data *rdp) + struct rcu_data *rdp) { if (rdp->quiescbatch != rcp->cur) { /* start new grace period: */ @@ -323,15 +302,15 @@ static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp, return; rdp->qs_pending = 0; - spin_lock(&rsp->lock); + spin_lock(&rcp->lock); /* * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync * during cpu startup. Ignore the quiescent state. */ if (likely(rdp->quiescbatch == rcp->cur)) - cpu_quiet(rdp->cpu, rcp, rsp); + cpu_quiet(rdp->cpu, rcp); - spin_unlock(&rsp->lock); + spin_unlock(&rcp->lock); } @@ -352,28 +331,29 @@ static void rcu_move_batch(struct rcu_data *this_rdp, struct rcu_head *list, } static void __rcu_offline_cpu(struct rcu_data *this_rdp, - struct rcu_ctrlblk *rcp, struct rcu_state *rsp, struct rcu_data *rdp) + struct rcu_ctrlblk *rcp, struct rcu_data *rdp) { /* if the cpu going offline owns the grace period * we can block indefinitely waiting for it, so flush * it here */ - spin_lock_bh(&rsp->lock); + spin_lock_bh(&rcp->lock); if (rcp->cur != rcp->completed) - cpu_quiet(rdp->cpu, rcp, rsp); - spin_unlock_bh(&rsp->lock); + cpu_quiet(rdp->cpu, rcp); + spin_unlock_bh(&rcp->lock); rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail); rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail); - + rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail); } + static void rcu_offline_cpu(int cpu) { struct rcu_data *this_rdp = &get_cpu_var(rcu_data); struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data); - __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, &rcu_state, + __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, &per_cpu(rcu_data, cpu)); - __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, &rcu_bh_state, + __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu)); put_cpu_var(rcu_data); put_cpu_var(rcu_bh_data); @@ -392,7 +372,7 @@ static void rcu_offline_cpu(int cpu) * This does the RCU processing work from tasklet context. */ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, - struct rcu_state *rsp, struct rcu_data *rdp) + struct rcu_data *rdp) { if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) { *rdp->donetail = rdp->curlist; @@ -422,24 +402,53 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, if (!rcp->next_pending) { /* and start it/schedule start if it's a new batch */ - spin_lock(&rsp->lock); - rcu_start_batch(rcp, rsp, 1); - spin_unlock(&rsp->lock); + spin_lock(&rcp->lock); + rcp->next_pending = 1; + rcu_start_batch(rcp); + spin_unlock(&rcp->lock); } } else { local_irq_enable(); } - rcu_check_quiescent_state(rcp, rsp, rdp); + rcu_check_quiescent_state(rcp, rdp); if (rdp->donelist) rcu_do_batch(rdp); } static void rcu_process_callbacks(unsigned long unused) { - __rcu_process_callbacks(&rcu_ctrlblk, &rcu_state, - &__get_cpu_var(rcu_data)); - __rcu_process_callbacks(&rcu_bh_ctrlblk, &rcu_bh_state, - &__get_cpu_var(rcu_bh_data)); + __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data)); + __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); +} + +static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp) +{ + /* This cpu has pending rcu entries and the grace period + * for them has completed. + */ + if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) + return 1; + + /* This cpu has no pending entries, but there are new entries */ + if (!rdp->curlist && rdp->nxtlist) + return 1; + + /* This cpu has finished callbacks to invoke */ + if (rdp->donelist) + return 1; + + /* The rcu core waits for a quiescent state from the cpu */ + if (rdp->quiescbatch != rcp->cur || rdp->qs_pending) + return 1; + + /* nothing to do */ + return 0; +} + +int rcu_pending(int cpu) +{ + return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) || + __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu)); } void rcu_check_callbacks(int cpu, int user) |