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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-25 03:53:42 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-25 03:53:42 -0300
commit03dd4cb26d967f9588437b0fc9cc0e8353322bb7 (patch)
treefa581f6dc1c0596391690d1f67eceef3af8246dc /kernel/rcu/tree_plugin.h
parentd4e493caf788ef44982e131ff9c786546904d934 (diff)
Linux-libre 4.5-gnu
Diffstat (limited to 'kernel/rcu/tree_plugin.h')
-rw-r--r--kernel/rcu/tree_plugin.h98
1 files changed, 48 insertions, 50 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 630c19772..080bd202d 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -63,8 +63,7 @@ static bool __read_mostly rcu_nocb_poll; /* Offload kthread are to poll. */
/*
* Check the RCU kernel configuration parameters and print informative
- * messages about anything out of the ordinary. If you like #ifdef, you
- * will love this function.
+ * messages about anything out of the ordinary.
*/
static void __init rcu_bootup_announce_oddness(void)
{
@@ -147,8 +146,8 @@ static void __init rcu_bootup_announce(void)
* the corresponding expedited grace period will also be the end of the
* normal grace period.
*/
-static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp,
- unsigned long flags) __releases(rnp->lock)
+static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
+ __releases(rnp->lock) /* But leaves rrupts disabled. */
{
int blkd_state = (rnp->gp_tasks ? RCU_GP_TASKS : 0) +
(rnp->exp_tasks ? RCU_EXP_TASKS : 0) +
@@ -236,7 +235,7 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp,
rnp->gp_tasks = &t->rcu_node_entry;
if (!rnp->exp_tasks && (blkd_state & RCU_EXP_BLKD))
rnp->exp_tasks = &t->rcu_node_entry;
- raw_spin_unlock(&rnp->lock);
+ raw_spin_unlock(&rnp->lock); /* rrupts remain disabled. */
/*
* Report the quiescent state for the expedited GP. This expedited
@@ -251,7 +250,6 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp,
} else {
WARN_ON_ONCE(t->rcu_read_unlock_special.b.exp_need_qs);
}
- local_irq_restore(flags);
}
/*
@@ -286,12 +284,11 @@ static void rcu_preempt_qs(void)
* predating the current grace period drain, in other words, until
* rnp->gp_tasks becomes NULL.
*
- * Caller must disable preemption.
+ * Caller must disable interrupts.
*/
static void rcu_preempt_note_context_switch(void)
{
struct task_struct *t = current;
- unsigned long flags;
struct rcu_data *rdp;
struct rcu_node *rnp;
@@ -301,8 +298,7 @@ static void rcu_preempt_note_context_switch(void)
/* Possibly blocking in an RCU read-side critical section. */
rdp = this_cpu_ptr(rcu_state_p->rda);
rnp = rdp->mynode;
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock();
+ raw_spin_lock_rcu_node(rnp);
t->rcu_read_unlock_special.b.blocked = true;
t->rcu_blocked_node = rnp;
@@ -318,7 +314,7 @@ static void rcu_preempt_note_context_switch(void)
(rnp->qsmask & rdp->grpmask)
? rnp->gpnum
: rnp->gpnum + 1);
- rcu_preempt_ctxt_queue(rnp, rdp, flags);
+ rcu_preempt_ctxt_queue(rnp, rdp);
} else if (t->rcu_read_lock_nesting < 0 &&
t->rcu_read_unlock_special.s) {
@@ -450,20 +446,13 @@ void rcu_read_unlock_special(struct task_struct *t)
/*
* Remove this task from the list it blocked on. The task
- * now remains queued on the rcu_node corresponding to
- * the CPU it first blocked on, so the first attempt to
- * acquire the task's rcu_node's ->lock will succeed.
- * Keep the loop and add a WARN_ON() out of sheer paranoia.
+ * now remains queued on the rcu_node corresponding to the
+ * CPU it first blocked on, so there is no longer any need
+ * to loop. Retain a WARN_ON_ONCE() out of sheer paranoia.
*/
- for (;;) {
- rnp = t->rcu_blocked_node;
- raw_spin_lock(&rnp->lock); /* irqs already disabled. */
- smp_mb__after_unlock_lock();
- if (rnp == t->rcu_blocked_node)
- break;
- WARN_ON_ONCE(1);
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
- }
+ rnp = t->rcu_blocked_node;
+ raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
+ WARN_ON_ONCE(rnp != t->rcu_blocked_node);
empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
empty_exp = sync_rcu_preempt_exp_done(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
@@ -527,7 +516,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
unsigned long flags;
struct task_struct *t;
- raw_spin_lock_irqsave(&rnp->lock, flags);
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (!rcu_preempt_blocked_readers_cgp(rnp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
@@ -748,6 +737,12 @@ void synchronize_rcu_expedited(void)
struct rcu_state *rsp = rcu_state_p;
unsigned long s;
+ /* If expedited grace periods are prohibited, fall back to normal. */
+ if (rcu_gp_is_normal()) {
+ wait_rcu_gp(call_rcu);
+ return;
+ }
+
s = rcu_exp_gp_seq_snap(rsp);
rnp_unlock = exp_funnel_lock(rsp, s);
@@ -788,7 +783,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier);
*/
static void __init __rcu_init_preempt(void)
{
- rcu_init_one(rcu_state_p, rcu_data_p);
+ rcu_init_one(rcu_state_p);
}
/*
@@ -989,8 +984,7 @@ static int rcu_boost(struct rcu_node *rnp)
READ_ONCE(rnp->boost_tasks) == NULL)
return 0; /* Nothing left to boost. */
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock();
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
/*
* Recheck under the lock: all tasks in need of boosting
@@ -1176,8 +1170,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
"rcub/%d", rnp_index);
if (IS_ERR(t))
return PTR_ERR(t);
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock();
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
rnp->boost_kthread_task = t;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
sp.sched_priority = kthread_prio;
@@ -1524,7 +1517,8 @@ static void rcu_prepare_for_idle(void)
struct rcu_state *rsp;
int tne;
- if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL))
+ if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL) ||
+ rcu_is_nocb_cpu(smp_processor_id()))
return;
/* Handle nohz enablement switches conservatively. */
@@ -1538,10 +1532,6 @@ static void rcu_prepare_for_idle(void)
if (!tne)
return;
- /* If this is a no-CBs CPU, no callbacks, just return. */
- if (rcu_is_nocb_cpu(smp_processor_id()))
- return;
-
/*
* If a non-lazy callback arrived at a CPU having only lazy
* callbacks, invoke RCU core for the side-effect of recalculating
@@ -1567,8 +1557,7 @@ static void rcu_prepare_for_idle(void)
if (!*rdp->nxttail[RCU_DONE_TAIL])
continue;
rnp = rdp->mynode;
- raw_spin_lock(&rnp->lock); /* irqs already disabled. */
- smp_mb__after_unlock_lock();
+ raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
needwake = rcu_accelerate_cbs(rsp, rnp, rdp);
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
if (needwake)
@@ -1822,9 +1811,9 @@ early_param("rcu_nocb_poll", parse_rcu_nocb_poll);
* Wake up any no-CBs CPUs' kthreads that were waiting on the just-ended
* grace period.
*/
-static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
+static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq)
{
- wake_up_all(&rnp->nocb_gp_wq[rnp->completed & 0x1]);
+ swake_up_all(sq);
}
/*
@@ -1840,10 +1829,15 @@ static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq)
rnp->need_future_gp[(rnp->completed + 1) & 0x1] += nrq;
}
+static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp)
+{
+ return &rnp->nocb_gp_wq[rnp->completed & 0x1];
+}
+
static void rcu_init_one_nocb(struct rcu_node *rnp)
{
- init_waitqueue_head(&rnp->nocb_gp_wq[0]);
- init_waitqueue_head(&rnp->nocb_gp_wq[1]);
+ init_swait_queue_head(&rnp->nocb_gp_wq[0]);
+ init_swait_queue_head(&rnp->nocb_gp_wq[1]);
}
#ifndef CONFIG_RCU_NOCB_CPU_ALL
@@ -1868,7 +1862,7 @@ static void wake_nocb_leader(struct rcu_data *rdp, bool force)
if (READ_ONCE(rdp_leader->nocb_leader_sleep) || force) {
/* Prior smp_mb__after_atomic() orders against prior enqueue. */
WRITE_ONCE(rdp_leader->nocb_leader_sleep, false);
- wake_up(&rdp_leader->nocb_wq);
+ swake_up(&rdp_leader->nocb_wq);
}
}
@@ -2068,8 +2062,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
bool needwake;
struct rcu_node *rnp = rdp->mynode;
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock();
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
needwake = rcu_start_future_gp(rnp, rdp, &c);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
if (needwake)
@@ -2081,7 +2074,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
*/
trace_rcu_future_gp(rnp, rdp, c, TPS("StartWait"));
for (;;) {
- wait_event_interruptible(
+ swait_event_interruptible(
rnp->nocb_gp_wq[c & 0x1],
(d = ULONG_CMP_GE(READ_ONCE(rnp->completed), c)));
if (likely(d))
@@ -2109,7 +2102,7 @@ wait_again:
/* Wait for callbacks to appear. */
if (!rcu_nocb_poll) {
trace_rcu_nocb_wake(my_rdp->rsp->name, my_rdp->cpu, "Sleep");
- wait_event_interruptible(my_rdp->nocb_wq,
+ swait_event_interruptible(my_rdp->nocb_wq,
!READ_ONCE(my_rdp->nocb_leader_sleep));
/* Memory barrier handled by smp_mb() calls below and repoll. */
} else if (firsttime) {
@@ -2184,7 +2177,7 @@ wait_again:
* List was empty, wake up the follower.
* Memory barriers supplied by atomic_long_add().
*/
- wake_up(&rdp->nocb_wq);
+ swake_up(&rdp->nocb_wq);
}
}
@@ -2205,7 +2198,7 @@ static void nocb_follower_wait(struct rcu_data *rdp)
if (!rcu_nocb_poll) {
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
"FollowerSleep");
- wait_event_interruptible(rdp->nocb_wq,
+ swait_event_interruptible(rdp->nocb_wq,
READ_ONCE(rdp->nocb_follower_head));
} else if (firsttime) {
/* Don't drown trace log with "Poll"! */
@@ -2364,7 +2357,7 @@ void __init rcu_init_nohz(void)
static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
{
rdp->nocb_tail = &rdp->nocb_head;
- init_waitqueue_head(&rdp->nocb_wq);
+ init_swait_queue_head(&rdp->nocb_wq);
rdp->nocb_follower_tail = &rdp->nocb_follower_head;
}
@@ -2514,7 +2507,7 @@ static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
return false;
}
-static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
+static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq)
{
}
@@ -2522,6 +2515,11 @@ static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq)
{
}
+static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp)
+{
+ return NULL;
+}
+
static void rcu_init_one_nocb(struct rcu_node *rnp)
{
}