#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>
#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. */
/* for current batch to proceed. */
};
-static struct rcu_state rcu_state ____cacheline_maxaligned_in_smp =
+static struct rcu_state rcu_state ____cacheline_internodealigned_in_smp =
{.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
-static struct rcu_state rcu_bh_state ____cacheline_maxaligned_in_smp =
+static struct rcu_state rcu_bh_state ____cacheline_internodealigned_in_smp =
{.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
DEFINE_PER_CPU(struct rcu_data, rcu_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.
local_irq_restore(flags);
}
+static atomic_t rcu_barrier_cpu_count;
+static struct semaphore rcu_barrier_sema;
+static struct completion rcu_barrier_completion;
+
/**
* call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
* @head: structure to be used for queueing the RCU updates.
return rcu_ctrlblk.completed;
}
+static void rcu_barrier_callback(struct rcu_head *notused)
+{
+ if (atomic_dec_and_test(&rcu_barrier_cpu_count))
+ complete(&rcu_barrier_completion);
+}
+
+/*
+ * Called with preemption disabled, and from cross-cpu IRQ context.
+ */
+static void rcu_barrier_func(void *notused)
+{
+ int cpu = smp_processor_id();
+ struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+ struct rcu_head *head;
+
+ head = &rdp->barrier;
+ atomic_inc(&rcu_barrier_cpu_count);
+ call_rcu(head, rcu_barrier_callback);
+}
+
+/**
+ * rcu_barrier - Wait until all the in-flight RCUs are complete.
+ */
+void rcu_barrier(void)
+{
+ BUG_ON(in_interrupt());
+ /* Take cpucontrol semaphore to protect against CPU hotplug */
+ down(&rcu_barrier_sema);
+ init_completion(&rcu_barrier_completion);
+ atomic_set(&rcu_barrier_cpu_count, 0);
+ on_each_cpu(rcu_barrier_func, NULL, 0, 1);
+ wait_for_completion(&rcu_barrier_completion);
+ up(&rcu_barrier_sema);
+}
+EXPORT_SYMBOL_GPL(rcu_barrier);
+
/*
* Invoke the completed RCU callbacks. They are expected to be in
* a per-cpu list.
if (rcp->next_pending &&
rcp->completed == rcp->cur) {
- /* Can't change, since spin lock held. */
- cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask);
-
rcp->next_pending = 0;
- /* next_pending == 0 must be visible in __rcu_process_callbacks()
- * before it can see new value of cur.
+ /*
+ * next_pending == 0 must be visible in
+ * __rcu_process_callbacks() before it can see new value of cur.
*/
smp_wmb();
rcp->cur++;
+
+ /*
+ * 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
+ * unnecessarily.
+ */
+ smp_mb();
+ cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask);
+
}
}
&__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)
{
if (user ||
*/
void __init rcu_init(void)
{
+ sema_init(&rcu_barrier_sema, 1);
rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE,
(void *)(long)smp_processor_id());
/* Register notifier for non-boot CPUs */
projects / powerpc.git / blobdiff