[PATCH v2 tip/core/rcu 6/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree.c

From: Paul E. McKenney
Date: Mon Mar 16 2015 - 14:43:59 EST

From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>

This commit moves kernel/rcu/tree.c from the old ACCESS_ONCE() API to
the new READ_ONCE() and WRITE_ONCE() APIs.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 184 +++++++++++++++++++++++++++---------------------------
1 file changed, 92 insertions(+), 92 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 5f48c22a975a..bafdef5b4e97 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -188,17 +188,17 @@ unsigned long rcutorture_vernum;
*/
unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
{
- return ACCESS_ONCE(rnp->qsmaskinitnext);
+ return READ_ONCE(rnp->qsmaskinitnext);
}

/*
- * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
+ * Return true if an RCU grace period is in progress. The READ_ONCE()s
* permit this function to be invoked without holding the root rcu_node
* structure's ->lock, but of course results can be subject to change.
*/
static int rcu_gp_in_progress(struct rcu_state *rsp)
{
- return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum);
+ return READ_ONCE(rsp->completed) != READ_ONCE(rsp->gpnum);
}

/*
@@ -275,8 +275,8 @@ static void rcu_momentary_dyntick_idle(void)
if (!(resched_mask & rsp->flavor_mask))
continue;
smp_mb(); /* rcu_sched_qs_mask before cond_resched_completed. */
- if (ACCESS_ONCE(rdp->mynode->completed) !=
- ACCESS_ONCE(rdp->cond_resched_completed))
+ if (READ_ONCE(rdp->mynode->completed) !=
+ READ_ONCE(rdp->cond_resched_completed))
continue;

/*
@@ -488,9 +488,9 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
break;
}
if (rsp != NULL) {
- *flags = ACCESS_ONCE(rsp->gp_flags);
- *gpnum = ACCESS_ONCE(rsp->gpnum);
- *completed = ACCESS_ONCE(rsp->completed);
+ *flags = READ_ONCE(rsp->gp_flags);
+ *gpnum = READ_ONCE(rsp->gpnum);
+ *completed = READ_ONCE(rsp->completed);
return;
}
*flags = 0;
@@ -536,10 +536,10 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
static int rcu_future_needs_gp(struct rcu_state *rsp)
{
struct rcu_node *rnp = rcu_get_root(rsp);
- int idx = (ACCESS_ONCE(rnp->completed) + 1) & 0x1;
+ int idx = (READ_ONCE(rnp->completed) + 1) & 0x1;
int *fp = &rnp->need_future_gp[idx];

- return ACCESS_ONCE(*fp);
+ return READ_ONCE(*fp);
}

/*
@@ -562,7 +562,7 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
return 1; /* Yes, this CPU has newly registered callbacks. */
for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++)
if (rdp->nxttail[i - 1] != rdp->nxttail[i] &&
- ULONG_CMP_LT(ACCESS_ONCE(rsp->completed),
+ ULONG_CMP_LT(READ_ONCE(rsp->completed),
rdp->nxtcompleted[i]))
return 1; /* Yes, CBs for future grace period. */
return 0; /* No grace period needed. */
@@ -1008,9 +1008,9 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
return 1;
} else {
- if (ULONG_CMP_LT(ACCESS_ONCE(rdp->gpnum) + ULONG_MAX / 4,
+ if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
rdp->mynode->gpnum))
- ACCESS_ONCE(rdp->gpwrap) = true;
+ WRITE_ONCE(rdp->gpwrap, true);
return 0;
}
}
@@ -1090,12 +1090,12 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
if (ULONG_CMP_GE(jiffies,
rdp->rsp->gp_start + jiffies_till_sched_qs) ||
ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) {
- if (!(ACCESS_ONCE(*rcrmp) & rdp->rsp->flavor_mask)) {
- ACCESS_ONCE(rdp->cond_resched_completed) =
- ACCESS_ONCE(rdp->mynode->completed);
+ if (!(READ_ONCE(*rcrmp) & rdp->rsp->flavor_mask)) {
+ WRITE_ONCE(rdp->cond_resched_completed,
+ READ_ONCE(rdp->mynode->completed));
smp_mb(); /* ->cond_resched_completed before *rcrmp. */
- ACCESS_ONCE(*rcrmp) =
- ACCESS_ONCE(*rcrmp) + rdp->rsp->flavor_mask;
+ WRITE_ONCE(*rcrmp,
+ READ_ONCE(*rcrmp) + rdp->rsp->flavor_mask);
resched_cpu(rdp->cpu); /* Force CPU into scheduler. */
rdp->rsp->jiffies_resched += 5; /* Enable beating. */
} else if (ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) {
@@ -1116,9 +1116,9 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
rsp->gp_start = j;
smp_wmb(); /* Record start time before stall time. */
j1 = rcu_jiffies_till_stall_check();
- ACCESS_ONCE(rsp->jiffies_stall) = j + j1;
+ WRITE_ONCE(rsp->jiffies_stall, j + j1);
rsp->jiffies_resched = j + j1 / 2;
- rsp->n_force_qs_gpstart = ACCESS_ONCE(rsp->n_force_qs);
+ rsp->n_force_qs_gpstart = READ_ONCE(rsp->n_force_qs);
}

/*
@@ -1130,7 +1130,7 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
unsigned long j;

j = jiffies;
- gpa = ACCESS_ONCE(rsp->gp_activity);
+ gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ)
pr_err("%s kthread starved for %ld jiffies!\n",
rsp->name, j - gpa);
@@ -1170,12 +1170,13 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
/* Only let one CPU complain about others per time interval. */

raw_spin_lock_irqsave(&rnp->lock, flags);
- delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall);
+ delta = jiffies - READ_ONCE(rsp->jiffies_stall);
if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
- ACCESS_ONCE(rsp->jiffies_stall) = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
+ WRITE_ONCE(rsp->jiffies_stall,
+ jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
raw_spin_unlock_irqrestore(&rnp->lock, flags);

/*
@@ -1209,12 +1210,12 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
if (ndetected) {
rcu_dump_cpu_stacks(rsp);
} else {
- if (ACCESS_ONCE(rsp->gpnum) != gpnum ||
- ACCESS_ONCE(rsp->completed) == gpnum) {
+ if (READ_ONCE(rsp->gpnum) != gpnum ||
+ READ_ONCE(rsp->completed) == gpnum) {
pr_err("INFO: Stall ended before state dump start\n");
} else {
j = jiffies;
- gpa = ACCESS_ONCE(rsp->gp_activity);
+ gpa = READ_ONCE(rsp->gp_activity);
pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n",
rsp->name, j - gpa, j, gpa,
jiffies_till_next_fqs,
@@ -1259,9 +1260,9 @@ static void print_cpu_stall(struct rcu_state *rsp)
rcu_dump_cpu_stacks(rsp);

raw_spin_lock_irqsave(&rnp->lock, flags);
- if (ULONG_CMP_GE(jiffies, ACCESS_ONCE(rsp->jiffies_stall)))
- ACCESS_ONCE(rsp->jiffies_stall) = jiffies +
- 3 * rcu_jiffies_till_stall_check() + 3;
+ if (ULONG_CMP_GE(jiffies, READ_ONCE(rsp->jiffies_stall)))
+ WRITE_ONCE(rsp->jiffies_stall,
+ jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
raw_spin_unlock_irqrestore(&rnp->lock, flags);

/*
@@ -1304,20 +1305,20 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
* Given this check, comparisons of jiffies, rsp->jiffies_stall,
* and rsp->gp_start suffice to forestall false positives.
*/
- gpnum = ACCESS_ONCE(rsp->gpnum);
+ gpnum = READ_ONCE(rsp->gpnum);
smp_rmb(); /* Pick up ->gpnum first... */
- js = ACCESS_ONCE(rsp->jiffies_stall);
+ js = READ_ONCE(rsp->jiffies_stall);
smp_rmb(); /* ...then ->jiffies_stall before the rest... */
- gps = ACCESS_ONCE(rsp->gp_start);
+ gps = READ_ONCE(rsp->gp_start);
smp_rmb(); /* ...and finally ->gp_start before ->completed. */
- completed = ACCESS_ONCE(rsp->completed);
+ completed = READ_ONCE(rsp->completed);
if (ULONG_CMP_GE(completed, gpnum) ||
ULONG_CMP_LT(j, js) ||
ULONG_CMP_GE(gps, js))
return; /* No stall or GP completed since entering function. */
rnp = rdp->mynode;
if (rcu_gp_in_progress(rsp) &&
- (ACCESS_ONCE(rnp->qsmask) & rdp->grpmask)) {
+ (READ_ONCE(rnp->qsmask) & rdp->grpmask)) {

/* We haven't checked in, so go dump stack. */
print_cpu_stall(rsp);
@@ -1344,7 +1345,7 @@ void rcu_cpu_stall_reset(void)
struct rcu_state *rsp;

for_each_rcu_flavor(rsp)
- ACCESS_ONCE(rsp->jiffies_stall) = jiffies + ULONG_MAX / 2;
+ WRITE_ONCE(rsp->jiffies_stall, jiffies + ULONG_MAX / 2);
}

/*
@@ -1454,7 +1455,7 @@ rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp,
* doing some extra useless work.
*/
if (rnp->gpnum != rnp->completed ||
- ACCESS_ONCE(rnp_root->gpnum) != ACCESS_ONCE(rnp_root->completed)) {
+ READ_ONCE(rnp_root->gpnum) != READ_ONCE(rnp_root->completed)) {
rnp->need_future_gp[c & 0x1]++;
trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleaf"));
goto out;
@@ -1539,7 +1540,7 @@ static int rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
static void rcu_gp_kthread_wake(struct rcu_state *rsp)
{
if (current == rsp->gp_kthread ||
- !ACCESS_ONCE(rsp->gp_flags) ||
+ !READ_ONCE(rsp->gp_flags) ||
!rsp->gp_kthread)
return;
wake_up(&rsp->gp_wq);
@@ -1674,7 +1675,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,

/* Handle the ends of any preceding grace periods first. */
if (rdp->completed == rnp->completed &&
- !unlikely(ACCESS_ONCE(rdp->gpwrap))) {
+ !unlikely(READ_ONCE(rdp->gpwrap))) {

/* No grace period end, so just accelerate recent callbacks. */
ret = rcu_accelerate_cbs(rsp, rnp, rdp);
@@ -1689,7 +1690,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuend"));
}

- if (rdp->gpnum != rnp->gpnum || unlikely(ACCESS_ONCE(rdp->gpwrap))) {
+ if (rdp->gpnum != rnp->gpnum || unlikely(READ_ONCE(rdp->gpwrap))) {
/*
* If the current grace period is waiting for this CPU,
* set up to detect a quiescent state, otherwise don't
@@ -1701,7 +1702,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
rdp->qs_pending = !!(rnp->qsmask & rdp->grpmask);
zero_cpu_stall_ticks(rdp);
- ACCESS_ONCE(rdp->gpwrap) = false;
+ WRITE_ONCE(rdp->gpwrap, false);
}
return ret;
}
@@ -1714,9 +1715,9 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)

local_irq_save(flags);
rnp = rdp->mynode;
- if ((rdp->gpnum == ACCESS_ONCE(rnp->gpnum) &&
- rdp->completed == ACCESS_ONCE(rnp->completed) &&
- !unlikely(ACCESS_ONCE(rdp->gpwrap))) || /* w/out lock. */
+ if ((rdp->gpnum == READ_ONCE(rnp->gpnum) &&
+ rdp->completed == READ_ONCE(rnp->completed) &&
+ !unlikely(READ_ONCE(rdp->gpwrap))) || /* w/out lock. */
!raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
local_irq_restore(flags);
return;
@@ -1737,15 +1738,15 @@ static int rcu_gp_init(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);

- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
- if (!ACCESS_ONCE(rsp->gp_flags)) {
+ if (!READ_ONCE(rsp->gp_flags)) {
/* Spurious wakeup, tell caller to go back to sleep. */
raw_spin_unlock_irq(&rnp->lock);
return 0;
}
- ACCESS_ONCE(rsp->gp_flags) = 0; /* Clear all flags: New grace period. */
+ WRITE_ONCE(rsp->gp_flags, 0); /* Clear all flags: New grace period. */

if (WARN_ON_ONCE(rcu_gp_in_progress(rsp))) {
/*
@@ -1831,9 +1832,9 @@ static int rcu_gp_init(struct rcu_state *rsp)
rdp = this_cpu_ptr(rsp->rda);
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
- ACCESS_ONCE(rnp->gpnum) = rsp->gpnum;
+ WRITE_ONCE(rnp->gpnum, rsp->gpnum);
if (WARN_ON_ONCE(rnp->completed != rsp->completed))
- ACCESS_ONCE(rnp->completed) = rsp->completed;
+ WRITE_ONCE(rnp->completed, rsp->completed);
if (rnp == rdp->mynode)
(void)__note_gp_changes(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp);
@@ -1842,7 +1843,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
rnp->grphi, rnp->qsmask);
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_INIT) &&
gp_init_delay > 0 &&
!(rsp->gpnum % (rcu_num_nodes * 3 * gp_init_delay)))
@@ -1862,7 +1863,7 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
unsigned long maxj;
struct rcu_node *rnp = rcu_get_root(rsp);

- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
rsp->n_force_qs++;
if (fqs_state == RCU_SAVE_DYNTICK) {
/* Collect dyntick-idle snapshots. */
@@ -1880,11 +1881,11 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
}
/* Clear flag to prevent immediate re-entry. */
- if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
+ if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
- ACCESS_ONCE(rsp->gp_flags) =
- ACCESS_ONCE(rsp->gp_flags) & ~RCU_GP_FLAG_FQS;
+ WRITE_ONCE(rsp->gp_flags,
+ READ_ONCE(rsp->gp_flags) & ~RCU_GP_FLAG_FQS);
raw_spin_unlock_irq(&rnp->lock);
}
return fqs_state;
@@ -1901,7 +1902,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);

- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
gp_duration = jiffies - rsp->gp_start;
@@ -1932,7 +1933,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
smp_mb__after_unlock_lock();
WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
WARN_ON_ONCE(rnp->qsmask);
- ACCESS_ONCE(rnp->completed) = rsp->gpnum;
+ WRITE_ONCE(rnp->completed, rsp->gpnum);
rdp = this_cpu_ptr(rsp->rda);
if (rnp == rdp->mynode)
needgp = __note_gp_changes(rsp, rnp, rdp) || needgp;
@@ -1940,7 +1941,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
nocb += rcu_future_gp_cleanup(rsp, rnp);
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
}
rnp = rcu_get_root(rsp);
raw_spin_lock_irq(&rnp->lock);
@@ -1948,16 +1949,16 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rcu_nocb_gp_set(rnp, nocb);

/* Declare grace period done. */
- ACCESS_ONCE(rsp->completed) = rsp->gpnum;
+ WRITE_ONCE(rsp->completed, rsp->gpnum);
trace_rcu_grace_period(rsp->name, rsp->completed, TPS("end"));
rsp->fqs_state = RCU_GP_IDLE;
rdp = this_cpu_ptr(rsp->rda);
/* Advance CBs to reduce false positives below. */
needgp = rcu_advance_cbs(rsp, rnp, rdp) || needgp;
if (needgp || cpu_needs_another_gp(rsp, rdp)) {
- ACCESS_ONCE(rsp->gp_flags) = RCU_GP_FLAG_INIT;
+ WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("newreq"));
}
raw_spin_unlock_irq(&rnp->lock);
@@ -1981,20 +1982,20 @@ static int __noreturn rcu_gp_kthread(void *arg)
/* Handle grace-period start. */
for (;;) {
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("reqwait"));
rsp->gp_state = RCU_GP_WAIT_GPS;
wait_event_interruptible(rsp->gp_wq,
- ACCESS_ONCE(rsp->gp_flags) &
+ READ_ONCE(rsp->gp_flags) &
RCU_GP_FLAG_INIT);
/* Locking provides needed memory barrier. */
if (rcu_gp_init(rsp))
break;
cond_resched_rcu_qs();
- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("reqwaitsig"));
}

@@ -2010,39 +2011,39 @@ static int __noreturn rcu_gp_kthread(void *arg)
if (!ret)
rsp->jiffies_force_qs = jiffies + j;
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("fqswait"));
rsp->gp_state = RCU_GP_WAIT_FQS;
ret = wait_event_interruptible_timeout(rsp->gp_wq,
- ((gf = ACCESS_ONCE(rsp->gp_flags)) &
+ ((gf = READ_ONCE(rsp->gp_flags)) &
RCU_GP_FLAG_FQS) ||
- (!ACCESS_ONCE(rnp->qsmask) &&
+ (!READ_ONCE(rnp->qsmask) &&
!rcu_preempt_blocked_readers_cgp(rnp)),
j);
/* Locking provides needed memory barriers. */
/* If grace period done, leave loop. */
- if (!ACCESS_ONCE(rnp->qsmask) &&
+ if (!READ_ONCE(rnp->qsmask) &&
!rcu_preempt_blocked_readers_cgp(rnp))
break;
/* If time for quiescent-state forcing, do it. */
if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) ||
(gf & RCU_GP_FLAG_FQS)) {
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("fqsstart"));
fqs_state = rcu_gp_fqs(rsp, fqs_state);
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("fqsend"));
cond_resched_rcu_qs();
- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
} else {
/* Deal with stray signal. */
cond_resched_rcu_qs();
- ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
- ACCESS_ONCE(rsp->gpnum),
+ READ_ONCE(rsp->gpnum),
TPS("fqswaitsig"));
}
j = jiffies_till_next_fqs;
@@ -2084,8 +2085,8 @@ rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
*/
return false;
}
- ACCESS_ONCE(rsp->gp_flags) = RCU_GP_FLAG_INIT;
- trace_rcu_grace_period(rsp->name, ACCESS_ONCE(rsp->gpnum),
+ WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
+ trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
TPS("newreq"));

/*
@@ -2355,7 +2356,7 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
rsp->qlen += rdp->qlen;
rdp->n_cbs_orphaned += rdp->qlen;
rdp->qlen_lazy = 0;
- ACCESS_ONCE(rdp->qlen) = 0;
+ WRITE_ONCE(rdp->qlen, 0);
}

/*
@@ -2567,7 +2568,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
/* If no callbacks are ready, just return. */
if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, 0);
- trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist),
+ trace_rcu_batch_end(rsp->name, 0, !!READ_ONCE(rdp->nxtlist),
need_resched(), is_idle_task(current),
rcu_is_callbacks_kthread());
return;
@@ -2623,7 +2624,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
}
smp_mb(); /* List handling before counting for rcu_barrier(). */
rdp->qlen_lazy -= count_lazy;
- ACCESS_ONCE(rdp->qlen) = rdp->qlen - count;
+ WRITE_ONCE(rdp->qlen, rdp->qlen - count);
rdp->n_cbs_invoked += count;

/* Reinstate batch limit if we have worked down the excess. */
@@ -2780,7 +2781,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
/* Funnel through hierarchy to reduce memory contention. */
rnp = __this_cpu_read(rsp->rda->mynode);
for (; rnp != NULL; rnp = rnp->parent) {
- ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
+ ret = (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
!raw_spin_trylock(&rnp->fqslock);
if (rnp_old != NULL)
raw_spin_unlock(&rnp_old->fqslock);
@@ -2796,13 +2797,12 @@ static void force_quiescent_state(struct rcu_state *rsp)
raw_spin_lock_irqsave(&rnp_old->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_unlock(&rnp_old->fqslock);
- if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
+ if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
rsp->n_force_qs_lh++;
raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
return; /* Someone beat us to it. */
}
- ACCESS_ONCE(rsp->gp_flags) =
- ACCESS_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS;
+ WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
rcu_gp_kthread_wake(rsp);
}
@@ -2868,7 +2868,7 @@ static void rcu_process_callbacks(struct softirq_action *unused)
*/
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
{
- if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active)))
+ if (unlikely(!READ_ONCE(rcu_scheduler_fully_active)))
return;
if (likely(!rsp->boost)) {
rcu_do_batch(rsp, rdp);
@@ -2959,7 +2959,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
WARN_ON_ONCE((unsigned long)head & 0x1); /* Misaligned rcu_head! */
if (debug_rcu_head_queue(head)) {
/* Probable double call_rcu(), so leak the callback. */
- ACCESS_ONCE(head->func) = rcu_leak_callback;
+ WRITE_ONCE(head->func, rcu_leak_callback);
WARN_ONCE(1, "__call_rcu(): Leaked duplicate callback\n");
return;
}
@@ -2998,7 +2998,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
if (!likely(rdp->nxtlist))
init_default_callback_list(rdp);
}
- ACCESS_ONCE(rdp->qlen) = rdp->qlen + 1;
+ WRITE_ONCE(rdp->qlen, rdp->qlen + 1);
if (lazy)
rdp->qlen_lazy++;
else
@@ -3437,14 +3437,14 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
}

/* Has another RCU grace period completed? */
- if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
+ if (READ_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
rdp->n_rp_gp_completed++;
return 1;
}

/* Has a new RCU grace period started? */
- if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum ||
- unlikely(ACCESS_ONCE(rdp->gpwrap))) { /* outside lock */
+ if (READ_ONCE(rnp->gpnum) != rdp->gpnum ||
+ unlikely(READ_ONCE(rdp->gpwrap))) { /* outside lock */
rdp->n_rp_gp_started++;
return 1;
}
@@ -3551,7 +3551,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
{
int cpu;
struct rcu_data *rdp;
- unsigned long snap = ACCESS_ONCE(rsp->n_barrier_done);
+ unsigned long snap = READ_ONCE(rsp->n_barrier_done);
unsigned long snap_done;

_rcu_barrier_trace(rsp, "Begin", -1, snap);
@@ -3593,10 +3593,10 @@ static void _rcu_barrier(struct rcu_state *rsp)

/*
* Increment ->n_barrier_done to avoid duplicate work. Use
- * ACCESS_ONCE() to prevent the compiler from speculating
+ * WRITE_ONCE() to prevent the compiler from speculating
* the increment to precede the early-exit check.
*/
- ACCESS_ONCE(rsp->n_barrier_done) = rsp->n_barrier_done + 1;
+ WRITE_ONCE(rsp->n_barrier_done, rsp->n_barrier_done + 1);
WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 1);
_rcu_barrier_trace(rsp, "Inc1", -1, rsp->n_barrier_done);
smp_mb(); /* Order ->n_barrier_done increment with below mechanism. */
@@ -3632,7 +3632,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
__call_rcu(&rdp->barrier_head,
rcu_barrier_callback, rsp, cpu, 0);
}
- } else if (ACCESS_ONCE(rdp->qlen)) {
+ } else if (READ_ONCE(rdp->qlen)) {
_rcu_barrier_trace(rsp, "OnlineQ", cpu,
rsp->n_barrier_done);
smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
@@ -3652,7 +3652,7 @@ static void _rcu_barrier(struct rcu_state *rsp)

/* Increment ->n_barrier_done to prevent duplicate work. */
smp_mb(); /* Keep increment after above mechanism. */
- ACCESS_ONCE(rsp->n_barrier_done) = rsp->n_barrier_done + 1;
+ WRITE_ONCE(rsp->n_barrier_done, rsp->n_barrier_done + 1);
WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 0);
_rcu_barrier_trace(rsp, "Inc2", -1, rsp->n_barrier_done);
smp_mb(); /* Keep increment before caller's subsequent code. */
--
1.8.1.5

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