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@@ -46,18 +46,22 @@
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#include <linux/cpu.h>
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#include <linux/mutex.h>
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#include <linux/time.h>
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+#include <linux/kernel_stat.h>
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#include "rcutree.h"
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/* Data structures. */
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+static struct lock_class_key rcu_node_class[NUM_RCU_LVLS];
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+
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#define RCU_STATE_INITIALIZER(name) { \
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.level = { &name.node[0] }, \
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.levelcnt = { \
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NUM_RCU_LVL_0, /* root of hierarchy. */ \
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NUM_RCU_LVL_1, \
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NUM_RCU_LVL_2, \
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- NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \
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+ NUM_RCU_LVL_3, \
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+ NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \
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}, \
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.signaled = RCU_GP_IDLE, \
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.gpnum = -300, \
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@@ -77,6 +81,8 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);
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struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
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DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
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+static int rcu_scheduler_active __read_mostly;
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+
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/*
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* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
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@@ -98,7 +104,7 @@ void rcu_sched_qs(int cpu)
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struct rcu_data *rdp;
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rdp = &per_cpu(rcu_sched_data, cpu);
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- rdp->passed_quiesc_completed = rdp->completed;
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+ rdp->passed_quiesc_completed = rdp->gpnum - 1;
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barrier();
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rdp->passed_quiesc = 1;
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rcu_preempt_note_context_switch(cpu);
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@@ -109,7 +115,7 @@ void rcu_bh_qs(int cpu)
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struct rcu_data *rdp;
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rdp = &per_cpu(rcu_bh_data, cpu);
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- rdp->passed_quiesc_completed = rdp->completed;
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+ rdp->passed_quiesc_completed = rdp->gpnum - 1;
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barrier();
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rdp->passed_quiesc = 1;
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}
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@@ -335,27 +341,8 @@ void rcu_irq_exit(void)
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set_need_resched();
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}
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-/*
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- * Record the specified "completed" value, which is later used to validate
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- * dynticks counter manipulations. Specify "rsp->completed - 1" to
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- * unconditionally invalidate any future dynticks manipulations (which is
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- * useful at the beginning of a grace period).
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- */
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-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
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-{
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- rsp->dynticks_completed = comp;
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-}
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-
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#ifdef CONFIG_SMP
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-/*
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- * Recall the previously recorded value of the completion for dynticks.
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- */
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-static long dyntick_recall_completed(struct rcu_state *rsp)
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-{
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- return rsp->dynticks_completed;
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-}
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-
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/*
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* Snapshot the specified CPU's dynticks counter so that we can later
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* credit them with an implicit quiescent state. Return 1 if this CPU
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@@ -419,24 +406,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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#else /* #ifdef CONFIG_NO_HZ */
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-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
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-{
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-}
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-
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#ifdef CONFIG_SMP
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-/*
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- * If there are no dynticks, then the only way that a CPU can passively
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- * be in a quiescent state is to be offline. Unlike dynticks idle, which
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- * is a point in time during the prior (already finished) grace period,
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- * an offline CPU is always in a quiescent state, and thus can be
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- * unconditionally applied. So just return the current value of completed.
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- */
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-static long dyntick_recall_completed(struct rcu_state *rsp)
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-{
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- return rsp->completed;
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-}
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-
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static int dyntick_save_progress_counter(struct rcu_data *rdp)
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{
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return 0;
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@@ -553,13 +524,33 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
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/*
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* Update CPU-local rcu_data state to record the newly noticed grace period.
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* This is used both when we started the grace period and when we notice
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- * that someone else started the grace period.
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+ * that someone else started the grace period. The caller must hold the
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+ * ->lock of the leaf rcu_node structure corresponding to the current CPU,
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+ * and must have irqs disabled.
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*/
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+static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
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+{
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+ if (rdp->gpnum != rnp->gpnum) {
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+ rdp->qs_pending = 1;
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+ rdp->passed_quiesc = 0;
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+ rdp->gpnum = rnp->gpnum;
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+ }
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+}
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+
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static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp)
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{
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- rdp->qs_pending = 1;
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- rdp->passed_quiesc = 0;
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- rdp->gpnum = rsp->gpnum;
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+ unsigned long flags;
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+ struct rcu_node *rnp;
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+
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+ local_irq_save(flags);
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+ rnp = rdp->mynode;
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+ if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */
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+ !spin_trylock(&rnp->lock)) { /* irqs already off, retry later. */
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+ local_irq_restore(flags);
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+ return;
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+ }
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+ __note_new_gpnum(rsp, rnp, rdp);
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+ spin_unlock_irqrestore(&rnp->lock, flags);
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}
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/*
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@@ -582,6 +573,79 @@ check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp)
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return ret;
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}
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+/*
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+ * Advance this CPU's callbacks, but only if the current grace period
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+ * has ended. This may be called only from the CPU to whom the rdp
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+ * belongs. In addition, the corresponding leaf rcu_node structure's
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+ * ->lock must be held by the caller, with irqs disabled.
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+ */
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+static void
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+__rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
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+{
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+ /* Did another grace period end? */
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+ if (rdp->completed != rnp->completed) {
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+
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+ /* Advance callbacks. No harm if list empty. */
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+ rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
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+ rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
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+ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
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+
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+ /* Remember that we saw this grace-period completion. */
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+ rdp->completed = rnp->completed;
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+ }
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+}
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+
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+/*
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+ * Advance this CPU's callbacks, but only if the current grace period
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+ * has ended. This may be called only from the CPU to whom the rdp
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+ * belongs.
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+ */
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+static void
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+rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
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+{
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+ unsigned long flags;
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+ struct rcu_node *rnp;
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+
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+ local_irq_save(flags);
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+ rnp = rdp->mynode;
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+ if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */
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+ !spin_trylock(&rnp->lock)) { /* irqs already off, retry later. */
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+ local_irq_restore(flags);
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+ return;
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+ }
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+ __rcu_process_gp_end(rsp, rnp, rdp);
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+ spin_unlock_irqrestore(&rnp->lock, flags);
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+}
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+
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+/*
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+ * Do per-CPU grace-period initialization for running CPU. The caller
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+ * must hold the lock of the leaf rcu_node structure corresponding to
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+ * this CPU.
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+ */
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+static void
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+rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
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+{
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+ /* Prior grace period ended, so advance callbacks for current CPU. */
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+ __rcu_process_gp_end(rsp, rnp, rdp);
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+
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+ /*
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+ * Because this CPU just now started the new grace period, we know
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+ * that all of its callbacks will be covered by this upcoming grace
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+ * period, even the ones that were registered arbitrarily recently.
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+ * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL.
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+ *
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+ * Other CPUs cannot be sure exactly when the grace period started.
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+ * Therefore, their recently registered callbacks must pass through
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+ * an additional RCU_NEXT_READY stage, so that they will be handled
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+ * by the next RCU grace period.
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+ */
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+ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
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+ rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
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+
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+ /* Set state so that this CPU will detect the next quiescent state. */
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+ __note_new_gpnum(rsp, rnp, rdp);
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+}
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+
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/*
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* Start a new RCU grace period if warranted, re-initializing the hierarchy
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* in preparation for detecting the next grace period. The caller must hold
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@@ -596,7 +660,23 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
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struct rcu_node *rnp = rcu_get_root(rsp);
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if (!cpu_needs_another_gp(rsp, rdp)) {
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- spin_unlock_irqrestore(&rnp->lock, flags);
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+ if (rnp->completed == rsp->completed) {
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+ spin_unlock_irqrestore(&rnp->lock, flags);
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+ return;
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+ }
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+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
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+
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+ /*
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+ * Propagate new ->completed value to rcu_node structures
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+ * so that other CPUs don't have to wait until the start
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+ * of the next grace period to process their callbacks.
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+ */
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+ rcu_for_each_node_breadth_first(rsp, rnp) {
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+ spin_lock(&rnp->lock); /* irqs already disabled. */
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+ rnp->completed = rsp->completed;
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+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
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+ }
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+ local_irq_restore(flags);
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return;
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}
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@@ -606,29 +686,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
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rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
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rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
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record_gp_stall_check_time(rsp);
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- dyntick_record_completed(rsp, rsp->completed - 1);
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- note_new_gpnum(rsp, rdp);
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-
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- /*
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- * Because this CPU just now started the new grace period, we know
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- * that all of its callbacks will be covered by this upcoming grace
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- * period, even the ones that were registered arbitrarily recently.
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- * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL.
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- *
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- * Other CPUs cannot be sure exactly when the grace period started.
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- * Therefore, their recently registered callbacks must pass through
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- * an additional RCU_NEXT_READY stage, so that they will be handled
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- * by the next RCU grace period.
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- */
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- rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
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- rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
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/* Special-case the common single-level case. */
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if (NUM_RCU_NODES == 1) {
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rcu_preempt_check_blocked_tasks(rnp);
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rnp->qsmask = rnp->qsmaskinit;
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rnp->gpnum = rsp->gpnum;
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+ rnp->completed = rsp->completed;
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rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */
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+ rcu_start_gp_per_cpu(rsp, rnp, rdp);
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spin_unlock_irqrestore(&rnp->lock, flags);
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return;
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}
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@@ -661,6 +727,9 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
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rcu_preempt_check_blocked_tasks(rnp);
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rnp->qsmask = rnp->qsmaskinit;
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rnp->gpnum = rsp->gpnum;
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+ rnp->completed = rsp->completed;
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+ if (rnp == rdp->mynode)
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+ rcu_start_gp_per_cpu(rsp, rnp, rdp);
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spin_unlock(&rnp->lock); /* irqs remain disabled. */
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}
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@@ -672,58 +741,32 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
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}
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/*
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- * Advance this CPU's callbacks, but only if the current grace period
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- * has ended. This may be called only from the CPU to whom the rdp
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- * belongs.
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+ * Report a full set of quiescent states to the specified rcu_state
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+ * data structure. This involves cleaning up after the prior grace
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+ * period and letting rcu_start_gp() start up the next grace period
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+ * if one is needed. Note that the caller must hold rnp->lock, as
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+ * required by rcu_start_gp(), which will release it.
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*/
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-static void
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-rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
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-{
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- long completed_snap;
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- unsigned long flags;
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-
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- local_irq_save(flags);
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- completed_snap = ACCESS_ONCE(rsp->completed); /* outside of lock. */
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-
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- /* Did another grace period end? */
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- if (rdp->completed != completed_snap) {
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-
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- /* Advance callbacks. No harm if list empty. */
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- rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
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- rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
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- rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
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-
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- /* Remember that we saw this grace-period completion. */
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- rdp->completed = completed_snap;
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- }
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- local_irq_restore(flags);
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-}
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-
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-/*
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- * Clean up after the prior grace period and let rcu_start_gp() start up
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- * the next grace period if one is needed. Note that the caller must
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- * hold rnp->lock, as required by rcu_start_gp(), which will release it.
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- */
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-static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags)
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+static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
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__releases(rcu_get_root(rsp)->lock)
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{
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WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
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rsp->completed = rsp->gpnum;
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rsp->signaled = RCU_GP_IDLE;
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- rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
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rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
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}
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/*
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- * Similar to cpu_quiet(), for which it is a helper function. Allows
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- * a group of CPUs to be quieted at one go, though all the CPUs in the
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- * group must be represented by the same leaf rcu_node structure.
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- * That structure's lock must be held upon entry, and it is released
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- * before return.
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+ * Similar to rcu_report_qs_rdp(), for which it is a helper function.
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+ * Allows quiescent states for a group of CPUs to be reported at one go
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+ * to the specified rcu_node structure, though all the CPUs in the group
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+ * must be represented by the same rcu_node structure (which need not be
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+ * a leaf rcu_node structure, though it often will be). That structure's
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+ * lock must be held upon entry, and it is released before return.
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*/
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static void
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-cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
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- unsigned long flags)
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+rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
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+ struct rcu_node *rnp, unsigned long flags)
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__releases(rnp->lock)
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{
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struct rcu_node *rnp_c;
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@@ -759,21 +802,23 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
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/*
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* Get here if we are the last CPU to pass through a quiescent
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- * state for this grace period. Invoke cpu_quiet_msk_finish()
|
|
|
+ * state for this grace period. Invoke rcu_report_qs_rsp()
|
|
|
* to clean up and start the next grace period if one is needed.
|
|
|
*/
|
|
|
- cpu_quiet_msk_finish(rsp, flags); /* releases rnp->lock. */
|
|
|
+ rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */
|
|
|
}
|
|
|
|
|
|
/*
|
|
|
- * Record a quiescent state for the specified CPU, which must either be
|
|
|
- * the current CPU. The lastcomp argument is used to make sure we are
|
|
|
- * still in the grace period of interest. We don't want to end the current
|
|
|
- * grace period based on quiescent states detected in an earlier grace
|
|
|
- * period!
|
|
|
+ * Record a quiescent state for the specified CPU to that CPU's rcu_data
|
|
|
+ * structure. This must be either called from the specified CPU, or
|
|
|
+ * called when the specified CPU is known to be offline (and when it is
|
|
|
+ * also known that no other CPU is concurrently trying to help the offline
|
|
|
+ * CPU). The lastcomp argument is used to make sure we are still in the
|
|
|
+ * grace period of interest. We don't want to end the current grace period
|
|
|
+ * based on quiescent states detected in an earlier grace period!
|
|
|
*/
|
|
|
static void
|
|
|
-cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
|
|
|
+rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
|
|
|
{
|
|
|
unsigned long flags;
|
|
|
unsigned long mask;
|
|
|
@@ -781,15 +826,15 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
|
|
|
|
|
|
rnp = rdp->mynode;
|
|
|
spin_lock_irqsave(&rnp->lock, flags);
|
|
|
- if (lastcomp != ACCESS_ONCE(rsp->completed)) {
|
|
|
+ if (lastcomp != rnp->completed) {
|
|
|
|
|
|
/*
|
|
|
* Someone beat us to it for this grace period, so leave.
|
|
|
* The race with GP start is resolved by the fact that we
|
|
|
* hold the leaf rcu_node lock, so that the per-CPU bits
|
|
|
* cannot yet be initialized -- so we would simply find our
|
|
|
- * CPU's bit already cleared in cpu_quiet_msk() if this race
|
|
|
- * occurred.
|
|
|
+ * CPU's bit already cleared in rcu_report_qs_rnp() if this
|
|
|
+ * race occurred.
|
|
|
*/
|
|
|
rdp->passed_quiesc = 0; /* try again later! */
|
|
|
spin_unlock_irqrestore(&rnp->lock, flags);
|
|
|
@@ -807,7 +852,7 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
|
|
|
*/
|
|
|
rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
|
|
|
|
|
|
- cpu_quiet_msk(mask, rsp, rnp, flags); /* releases rnp->lock */
|
|
|
+ rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */
|
|
|
}
|
|
|
}
|
|
|
|
|
|
@@ -838,8 +883,11 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
|
|
|
if (!rdp->passed_quiesc)
|
|
|
return;
|
|
|
|
|
|
- /* Tell RCU we are done (but cpu_quiet() will be the judge of that). */
|
|
|
- cpu_quiet(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
|
|
|
+ /*
|
|
|
+ * Tell RCU we are done (but rcu_report_qs_rdp() will be the
|
|
|
+ * judge of that).
|
|
|
+ */
|
|
|
+ rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
|
|
|
}
|
|
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
|
@@ -899,8 +947,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
|
|
|
static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
|
|
|
{
|
|
|
unsigned long flags;
|
|
|
- long lastcomp;
|
|
|
unsigned long mask;
|
|
|
+ int need_report = 0;
|
|
|
struct rcu_data *rdp = rsp->rda[cpu];
|
|
|
struct rcu_node *rnp;
|
|
|
|
|
|
@@ -914,30 +962,32 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
|
|
|
spin_lock(&rnp->lock); /* irqs already disabled. */
|
|
|
rnp->qsmaskinit &= ~mask;
|
|
|
if (rnp->qsmaskinit != 0) {
|
|
|
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
|
|
+ if (rnp != rdp->mynode)
|
|
|
+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
|
|
break;
|
|
|
}
|
|
|
-
|
|
|
- /*
|
|
|
- * If there was a task blocking the current grace period,
|
|
|
- * and if all CPUs have checked in, we need to propagate
|
|
|
- * the quiescent state up the rcu_node hierarchy. But that
|
|
|
- * is inconvenient at the moment due to deadlock issues if
|
|
|
- * this should end the current grace period. So set the
|
|
|
- * offlined CPU's bit in ->qsmask in order to force the
|
|
|
- * next force_quiescent_state() invocation to clean up this
|
|
|
- * mess in a deadlock-free manner.
|
|
|
- */
|
|
|
- if (rcu_preempt_offline_tasks(rsp, rnp, rdp) && !rnp->qsmask)
|
|
|
- rnp->qsmask |= mask;
|
|
|
-
|
|
|
+ if (rnp == rdp->mynode)
|
|
|
+ need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
|
|
|
+ else
|
|
|
+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
|
|
mask = rnp->grpmask;
|
|
|
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
|
|
|
rnp = rnp->parent;
|
|
|
} while (rnp != NULL);
|
|
|
- lastcomp = rsp->completed;
|
|
|
|
|
|
- spin_unlock_irqrestore(&rsp->onofflock, flags);
|
|
|
+ /*
|
|
|
+ * We still hold the leaf rcu_node structure lock here, and
|
|
|
+ * irqs are still disabled. The reason for this subterfuge is
|
|
|
+ * because invoking rcu_report_unblock_qs_rnp() with ->onofflock
|
|
|
+ * held leads to deadlock.
|
|
|
+ */
|
|
|
+ spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
|
|
|
+ rnp = rdp->mynode;
|
|
|
+ if (need_report & RCU_OFL_TASKS_NORM_GP)
|
|
|
+ rcu_report_unblock_qs_rnp(rnp, flags);
|
|
|
+ else
|
|
|
+ spin_unlock_irqrestore(&rnp->lock, flags);
|
|
|
+ if (need_report & RCU_OFL_TASKS_EXP_GP)
|
|
|
+ rcu_report_exp_rnp(rsp, rnp);
|
|
|
|
|
|
rcu_adopt_orphan_cbs(rsp);
|
|
|
}
|
|
|
@@ -1109,7 +1159,7 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
|
|
|
rcu_for_each_leaf_node(rsp, rnp) {
|
|
|
mask = 0;
|
|
|
spin_lock_irqsave(&rnp->lock, flags);
|
|
|
- if (rsp->completed != lastcomp) {
|
|
|
+ if (rnp->completed != lastcomp) {
|
|
|
spin_unlock_irqrestore(&rnp->lock, flags);
|
|
|
return 1;
|
|
|
}
|
|
|
@@ -1123,10 +1173,10 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
|
|
|
if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
|
|
|
mask |= bit;
|
|
|
}
|
|
|
- if (mask != 0 && rsp->completed == lastcomp) {
|
|
|
+ if (mask != 0 && rnp->completed == lastcomp) {
|
|
|
|
|
|
- /* cpu_quiet_msk() releases rnp->lock. */
|
|
|
- cpu_quiet_msk(mask, rsp, rnp, flags);
|
|
|
+ /* rcu_report_qs_rnp() releases rnp->lock. */
|
|
|
+ rcu_report_qs_rnp(mask, rsp, rnp, flags);
|
|
|
continue;
|
|
|
}
|
|
|
spin_unlock_irqrestore(&rnp->lock, flags);
|
|
|
@@ -1144,6 +1194,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
|
|
|
long lastcomp;
|
|
|
struct rcu_node *rnp = rcu_get_root(rsp);
|
|
|
u8 signaled;
|
|
|
+ u8 forcenow;
|
|
|
|
|
|
if (!rcu_gp_in_progress(rsp))
|
|
|
return; /* No grace period in progress, nothing to force. */
|
|
|
@@ -1156,10 +1207,10 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
|
|
|
goto unlock_ret; /* no emergency and done recently. */
|
|
|
rsp->n_force_qs++;
|
|
|
spin_lock(&rnp->lock);
|
|
|
- lastcomp = rsp->completed;
|
|
|
+ lastcomp = rsp->gpnum - 1;
|
|
|
signaled = rsp->signaled;
|
|
|
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
|
|
|
- if (lastcomp == rsp->gpnum) {
|
|
|
+ if(!rcu_gp_in_progress(rsp)) {
|
|
|
rsp->n_force_qs_ngp++;
|
|
|
spin_unlock(&rnp->lock);
|
|
|
goto unlock_ret; /* no GP in progress, time updated. */
|
|
|
@@ -1180,21 +1231,29 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
|
|
|
if (rcu_process_dyntick(rsp, lastcomp,
|
|
|
dyntick_save_progress_counter))
|
|
|
goto unlock_ret;
|
|
|
+ /* fall into next case. */
|
|
|
+
|
|
|
+ case RCU_SAVE_COMPLETED:
|
|
|
|
|
|
/* Update state, record completion counter. */
|
|
|
+ forcenow = 0;
|
|
|
spin_lock(&rnp->lock);
|
|
|
- if (lastcomp == rsp->completed &&
|
|
|
- rsp->signaled == RCU_SAVE_DYNTICK) {
|
|
|
+ if (lastcomp + 1 == rsp->gpnum &&
|
|
|
+ lastcomp == rsp->completed &&
|
|
|
+ rsp->signaled == signaled) {
|
|
|
rsp->signaled = RCU_FORCE_QS;
|
|
|
- dyntick_record_completed(rsp, lastcomp);
|
|
|
+ rsp->completed_fqs = lastcomp;
|
|
|
+ forcenow = signaled == RCU_SAVE_COMPLETED;
|
|
|
}
|
|
|
spin_unlock(&rnp->lock);
|
|
|
- break;
|
|
|
+ if (!forcenow)
|
|
|
+ break;
|
|
|
+ /* fall into next case. */
|
|
|
|
|
|
case RCU_FORCE_QS:
|
|
|
|
|
|
/* Check dyntick-idle state, send IPI to laggarts. */
|
|
|
- if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),
|
|
|
+ if (rcu_process_dyntick(rsp, rsp->completed_fqs,
|
|
|
rcu_implicit_dynticks_qs))
|
|
|
goto unlock_ret;
|
|
|
|
|
|
@@ -1351,6 +1410,68 @@ void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
|
|
|
}
|
|
|
EXPORT_SYMBOL_GPL(call_rcu_bh);
|
|
|
|
|
|
+/**
|
|
|
+ * synchronize_sched - wait until an rcu-sched grace period has elapsed.
|
|
|
+ *
|
|
|
+ * Control will return to the caller some time after a full rcu-sched
|
|
|
+ * grace period has elapsed, in other words after all currently executing
|
|
|
+ * rcu-sched read-side critical sections have completed. These read-side
|
|
|
+ * critical sections are delimited by rcu_read_lock_sched() and
|
|
|
+ * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(),
|
|
|
+ * local_irq_disable(), and so on may be used in place of
|
|
|
+ * rcu_read_lock_sched().
|
|
|
+ *
|
|
|
+ * This means that all preempt_disable code sequences, including NMI and
|
|
|
+ * hardware-interrupt handlers, in progress on entry will have completed
|
|
|
+ * before this primitive returns. However, this does not guarantee that
|
|
|
+ * softirq handlers will have completed, since in some kernels, these
|
|
|
+ * handlers can run in process context, and can block.
|
|
|
+ *
|
|
|
+ * This primitive provides the guarantees made by the (now removed)
|
|
|
+ * synchronize_kernel() API. In contrast, synchronize_rcu() only
|
|
|
+ * guarantees that rcu_read_lock() sections will have completed.
|
|
|
+ * In "classic RCU", these two guarantees happen to be one and
|
|
|
+ * the same, but can differ in realtime RCU implementations.
|
|
|
+ */
|
|
|
+void synchronize_sched(void)
|
|
|
+{
|
|
|
+ struct rcu_synchronize rcu;
|
|
|
+
|
|
|
+ if (rcu_blocking_is_gp())
|
|
|
+ return;
|
|
|
+
|
|
|
+ init_completion(&rcu.completion);
|
|
|
+ /* Will wake me after RCU finished. */
|
|
|
+ call_rcu_sched(&rcu.head, wakeme_after_rcu);
|
|
|
+ /* Wait for it. */
|
|
|
+ wait_for_completion(&rcu.completion);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(synchronize_sched);
|
|
|
+
|
|
|
+/**
|
|
|
+ * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
|
|
|
+ *
|
|
|
+ * Control will return to the caller some time after a full rcu_bh grace
|
|
|
+ * period has elapsed, in other words after all currently executing rcu_bh
|
|
|
+ * read-side critical sections have completed. RCU read-side critical
|
|
|
+ * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
|
|
|
+ * and may be nested.
|
|
|
+ */
|
|
|
+void synchronize_rcu_bh(void)
|
|
|
+{
|
|
|
+ struct rcu_synchronize rcu;
|
|
|
+
|
|
|
+ if (rcu_blocking_is_gp())
|
|
|
+ return;
|
|
|
+
|
|
|
+ init_completion(&rcu.completion);
|
|
|
+ /* Will wake me after RCU finished. */
|
|
|
+ call_rcu_bh(&rcu.head, wakeme_after_rcu);
|
|
|
+ /* Wait for it. */
|
|
|
+ wait_for_completion(&rcu.completion);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
|
|
|
+
|
|
|
/*
|
|
|
* Check to see if there is any immediate RCU-related work to be done
|
|
|
* by the current CPU, for the specified type of RCU, returning 1 if so.
|
|
|
@@ -1360,6 +1481,8 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
|
|
|
*/
|
|
|
static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
|
|
|
{
|
|
|
+ struct rcu_node *rnp = rdp->mynode;
|
|
|
+
|
|
|
rdp->n_rcu_pending++;
|
|
|
|
|
|
/* Check for CPU stalls, if enabled. */
|
|
|
@@ -1384,13 +1507,13 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
|
|
|
}
|
|
|
|
|
|
/* Has another RCU grace period completed? */
|
|
|
- if (ACCESS_ONCE(rsp->completed) != rdp->completed) { /* outside lock */
|
|
|
+ if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
|
|
|
rdp->n_rp_gp_completed++;
|
|
|
return 1;
|
|
|
}
|
|
|
|
|
|
/* Has a new RCU grace period started? */
|
|
|
- if (ACCESS_ONCE(rsp->gpnum) != rdp->gpnum) { /* outside lock */
|
|
|
+ if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */
|
|
|
rdp->n_rp_gp_started++;
|
|
|
return 1;
|
|
|
}
|
|
|
@@ -1433,6 +1556,21 @@ int rcu_needs_cpu(int cpu)
|
|
|
rcu_preempt_needs_cpu(cpu);
|
|
|
}
|
|
|
|
|
|
+/*
|
|
|
+ * This function is invoked towards the end of the scheduler's initialization
|
|
|
+ * process. Before this is called, the idle task might contain
|
|
|
+ * RCU read-side critical sections (during which time, this idle
|
|
|
+ * task is booting the system). After this function is called, the
|
|
|
+ * idle tasks are prohibited from containing RCU read-side critical
|
|
|
+ * sections.
|
|
|
+ */
|
|
|
+void rcu_scheduler_starting(void)
|
|
|
+{
|
|
|
+ WARN_ON(num_online_cpus() != 1);
|
|
|
+ WARN_ON(nr_context_switches() > 0);
|
|
|
+ rcu_scheduler_active = 1;
|
|
|
+}
|
|
|
+
|
|
|
static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};
|
|
|
static atomic_t rcu_barrier_cpu_count;
|
|
|
static DEFINE_MUTEX(rcu_barrier_mutex);
|
|
|
@@ -1544,21 +1682,16 @@ static void __cpuinit
|
|
|
rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
|
|
|
{
|
|
|
unsigned long flags;
|
|
|
- long lastcomp;
|
|
|
unsigned long mask;
|
|
|
struct rcu_data *rdp = rsp->rda[cpu];
|
|
|
struct rcu_node *rnp = rcu_get_root(rsp);
|
|
|
|
|
|
/* Set up local state, ensuring consistent view of global state. */
|
|
|
spin_lock_irqsave(&rnp->lock, flags);
|
|
|
- lastcomp = rsp->completed;
|
|
|
- rdp->completed = lastcomp;
|
|
|
- rdp->gpnum = lastcomp;
|
|
|
rdp->passed_quiesc = 0; /* We could be racing with new GP, */
|
|
|
rdp->qs_pending = 1; /* so set up to respond to current GP. */
|
|
|
rdp->beenonline = 1; /* We have now been online. */
|
|
|
rdp->preemptable = preemptable;
|
|
|
- rdp->passed_quiesc_completed = lastcomp - 1;
|
|
|
rdp->qlen_last_fqs_check = 0;
|
|
|
rdp->n_force_qs_snap = rsp->n_force_qs;
|
|
|
rdp->blimit = blimit;
|
|
|
@@ -1580,6 +1713,11 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
|
|
|
spin_lock(&rnp->lock); /* irqs already disabled. */
|
|
|
rnp->qsmaskinit |= mask;
|
|
|
mask = rnp->grpmask;
|
|
|
+ if (rnp == rdp->mynode) {
|
|
|
+ rdp->gpnum = rnp->completed; /* if GP in progress... */
|
|
|
+ rdp->completed = rnp->completed;
|
|
|
+ rdp->passed_quiesc_completed = rnp->completed - 1;
|
|
|
+ }
|
|
|
spin_unlock(&rnp->lock); /* irqs already disabled. */
|
|
|
rnp = rnp->parent;
|
|
|
} while (rnp != NULL && !(rnp->qsmaskinit & mask));
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@@ -1597,8 +1735,8 @@ static void __cpuinit rcu_online_cpu(int cpu)
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/*
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* Handle CPU online/offline notification events.
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*/
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-int __cpuinit rcu_cpu_notify(struct notifier_block *self,
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- unsigned long action, void *hcpu)
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+static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
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+ unsigned long action, void *hcpu)
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{
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long cpu = (long)hcpu;
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@@ -1685,8 +1823,8 @@ static void __init rcu_init_one(struct rcu_state *rsp)
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cpustride *= rsp->levelspread[i];
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rnp = rsp->level[i];
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for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
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- if (rnp != rcu_get_root(rsp))
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- spin_lock_init(&rnp->lock);
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+ spin_lock_init(&rnp->lock);
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+ lockdep_set_class(&rnp->lock, &rcu_node_class[i]);
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rnp->gpnum = 0;
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rnp->qsmask = 0;
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rnp->qsmaskinit = 0;
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@@ -1707,9 +1845,10 @@ static void __init rcu_init_one(struct rcu_state *rsp)
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rnp->level = i;
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INIT_LIST_HEAD(&rnp->blocked_tasks[0]);
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INIT_LIST_HEAD(&rnp->blocked_tasks[1]);
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+ INIT_LIST_HEAD(&rnp->blocked_tasks[2]);
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+ INIT_LIST_HEAD(&rnp->blocked_tasks[3]);
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}
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}
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- spin_lock_init(&rcu_get_root(rsp)->lock);
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}
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/*
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@@ -1735,16 +1874,30 @@ do { \
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} \
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} while (0)
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-void __init __rcu_init(void)
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+void __init rcu_init(void)
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{
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+ int i;
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+
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rcu_bootup_announce();
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#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
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printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
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#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
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+#if NUM_RCU_LVL_4 != 0
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+ printk(KERN_INFO "Experimental four-level hierarchy is enabled.\n");
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+#endif /* #if NUM_RCU_LVL_4 != 0 */
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RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data);
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RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data);
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__rcu_init_preempt();
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open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
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+
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+ /*
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+ * We don't need protection against CPU-hotplug here because
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+ * this is called early in boot, before either interrupts
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+ * or the scheduler are operational.
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+ */
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+ cpu_notifier(rcu_cpu_notify, 0);
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+ for_each_online_cpu(i)
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+ rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)i);
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}
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#include "rcutree_plugin.h"
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Linus Torvalds