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rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()

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This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE()
and WRITE_ONCE() APIs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck:  Updated to include kernel/torture.c as suggested by Jason Low. ]
This commit is contained in:
Paul E. McKenney 2015-03-03 14:57:58 -08:00
parent 030bbdbf4c
commit 7d0ae8086b
10 changed files with 193 additions and 192 deletions
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6
include/linux/rculist.h
View file

@ -29,8 +29,8 @@
*/
static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
{
ACCESS_ONCE(list->next) = list;
ACCESS_ONCE(list->prev) = list;
WRITE_ONCE(list->next, list);
WRITE_ONCE(list->prev, list);
}
/*
@ -288,7 +288,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
#define list_first_or_null_rcu(ptr, type, member) \
({ \
struct list_head *__ptr = (ptr); \
struct list_head *__next = ACCESS_ONCE(__ptr->next); \
struct list_head *__next = READ_ONCE(__ptr->next); \
likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \
})

16
include/linux/rcupdate.h
View file

@ -364,8 +364,8 @@ extern struct srcu_struct tasks_rcu_exit_srcu;
#define rcu_note_voluntary_context_switch(t) \
do { \
rcu_all_qs(); \
if (ACCESS_ONCE((t)->rcu_tasks_holdout)) \
ACCESS_ONCE((t)->rcu_tasks_holdout) = false; \
if (READ_ONCE((t)->rcu_tasks_holdout)) \
WRITE_ONCE((t)->rcu_tasks_holdout, false); \
} while (0)
#else /* #ifdef CONFIG_TASKS_RCU */
#define TASKS_RCU(x) do { } while (0)
@ -609,7 +609,7 @@ static inline void rcu_preempt_sleep_check(void)
#define __rcu_access_pointer(p, space) \
({ \
typeof(*p) *_________p1 = (typeof(*p) *__force)ACCESS_ONCE(p); \
typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \
rcu_dereference_sparse(p, space); \
((typeof(*p) __force __kernel *)(_________p1)); \
})
@ -630,7 +630,7 @@ static inline void rcu_preempt_sleep_check(void)
#define __rcu_access_index(p, space) \
({ \
typeof(p) _________p1 = ACCESS_ONCE(p); \
typeof(p) _________p1 = READ_ONCE(p); \
rcu_dereference_sparse(p, space); \
(_________p1); \
})
@ -659,7 +659,7 @@ static inline void rcu_preempt_sleep_check(void)
*/
#define lockless_dereference(p) \
({ \
typeof(p) _________p1 = ACCESS_ONCE(p); \
typeof(p) _________p1 = READ_ONCE(p); \
smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
(_________p1); \
})
@ -702,7 +702,7 @@ static inline void rcu_preempt_sleep_check(void)
* @p: The pointer to read
*
* Return the value of the specified RCU-protected pointer, but omit the
* smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful
* smp_read_barrier_depends() and keep the READ_ONCE(). This is useful
* when the value of this pointer is accessed, but the pointer is not
* dereferenced, for example, when testing an RCU-protected pointer against
* NULL. Although rcu_access_pointer() may also be used in cases where
@ -791,7 +791,7 @@ static inline void rcu_preempt_sleep_check(void)
* @p: The index to read
*
* Return the value of the specified RCU-protected index, but omit the
* smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful
* smp_read_barrier_depends() and keep the READ_ONCE(). This is useful
* when the value of this index is accessed, but the index is not
* dereferenced, for example, when testing an RCU-protected index against
* -1. Although rcu_access_index() may also be used in cases where
@ -827,7 +827,7 @@ static inline void rcu_preempt_sleep_check(void)
* @c: The conditions under which the dereference will take place
*
* Return the value of the specified RCU-protected pointer, but omit
* both the smp_read_barrier_depends() and the ACCESS_ONCE(). This
* both the smp_read_barrier_depends() and the READ_ONCE(). This
* is useful in cases where update-side locks prevent the value of the
* pointer from changing. Please note that this primitive does -not-
* prevent the compiler from repeating this reference or combining it

2
kernel/rcu/rcutorture.c
View file

@ -1413,7 +1413,7 @@ static int rcu_torture_barrier_cbs(void *arg)
do {
wait_event(barrier_cbs_wq[myid],
(newphase =
ACCESS_ONCE(barrier_phase)) != lastphase ||
READ_ONCE(barrier_phase)) != lastphase ||
torture_must_stop());
lastphase = newphase;
smp_mb(); /* ensure barrier_phase load before ->call(). */

10
kernel/rcu/srcu.c
View file

@ -151,7 +151,7 @@ static unsigned long srcu_readers_seq_idx(struct srcu_struct *sp, int idx)
unsigned long t;
for_each_possible_cpu(cpu) {
t = ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->seq[idx]);
t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->seq[idx]);
sum += t;
}
return sum;
@ -168,7 +168,7 @@ static unsigned long srcu_readers_active_idx(struct srcu_struct *sp, int idx)
unsigned long t;
for_each_possible_cpu(cpu) {
t = ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx]);
t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx]);
sum += t;
}
return sum;
@ -265,8 +265,8 @@ static int srcu_readers_active(struct srcu_struct *sp)
unsigned long sum = 0;
for_each_possible_cpu(cpu) {
sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]);
sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]);
sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]);
sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]);
}
return sum;
}
@ -296,7 +296,7 @@ int __srcu_read_lock(struct srcu_struct *sp)
{
int idx;
idx = ACCESS_ONCE(sp->completed) & 0x1;
idx = READ_ONCE(sp->completed) & 0x1;
preempt_disable();
__this_cpu_inc(sp->per_cpu_ref->c[idx]);
smp_mb(); /* B */ /* Avoid leaking the critical section. */

12
kernel/rcu/tiny_plugin.h
View file

@ -144,16 +144,17 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp)
return;
rcp->ticks_this_gp++;
j = jiffies;
js = ACCESS_ONCE(rcp->jiffies_stall);
js = READ_ONCE(rcp->jiffies_stall);
if (rcp->rcucblist && ULONG_CMP_GE(j, js)) {
pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
rcp->name, rcp->ticks_this_gp, DYNTICK_TASK_EXIT_IDLE,
jiffies - rcp->gp_start, rcp->qlen);
dump_stack();
ACCESS_ONCE(rcp->jiffies_stall) = jiffies +
3 * rcu_jiffies_till_stall_check() + 3;
WRITE_ONCE(rcp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
} else if (ULONG_CMP_GE(j, js)) {
ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check();
WRITE_ONCE(rcp->jiffies_stall,
jiffies + rcu_jiffies_till_stall_check());
}
}
@ -161,7 +162,8 @@ static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
{
rcp->ticks_this_gp = 0;
rcp->gp_start = jiffies;
ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check();
WRITE_ONCE(rcp->jiffies_stall,
jiffies + rcu_jiffies_till_stall_check());
}
static void check_cpu_stalls(void)

184
kernel/rcu/tree.c
View file

@ -191,17 +191,17 @@ 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);
}
/*
@ -278,8 +278,8 @@ 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;
/*
@ -491,9 +491,9 @@ 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;
@ -539,10 +539,10 @@ 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);
}
/*
@ -565,7 +565,7 @@ 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. */
@ -1011,9 +1011,9 @@ 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;
}
}
@ -1093,12 +1093,12 @@ 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)) {
@ -1119,9 +1119,9 @@ 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);
}
/*
@ -1133,7 +1133,7 @@ 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);
@ -1173,12 +1173,13 @@ 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);
/*
@ -1212,12 +1213,12 @@ 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,
@ -1262,9 +1263,9 @@ 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);
/*
@ -1307,20 +1308,20 @@ 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);
@ -1347,7 +1348,7 @@ 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);
}
/*
@ -1457,7 +1458,7 @@ 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;
@ -1542,7 +1543,7 @@ 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);
@ -1677,7 +1678,7 @@ 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);
@ -1692,7 +1693,7 @@ 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
@ -1704,7 +1705,7 @@ 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;
}
@ -1717,9 +1718,9 @@ 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;
@ -1740,15 +1741,15 @@ 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))) {
/*
@ -1834,9 +1835,9 @@ 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);
@ -1845,7 +1846,7 @@ 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 (gp_init_delay > 0 &&
!(rsp->gpnum % (rcu_num_nodes * PER_RCU_NODE_PERIOD)))
schedule_timeout_uninterruptible(gp_init_delay);
@ -1864,7 +1865,7 @@ 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. */
@ -1882,11 +1883,11 @@ 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;
@ -1903,7 +1904,7 @@ 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;
@ -1934,7 +1935,7 @@ 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;
@ -1942,7 +1943,7 @@ 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);
@ -1950,16 +1951,16 @@ 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);
@ -1983,20 +1984,20 @@ 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"));
}
@ -2012,39 +2013,39 @@ 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;
@ -2086,8 +2087,8 @@ 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"));
/*
@ -2359,7 +2360,7 @@ 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);
}
/*
@ -2580,7 +2581,7 @@ 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;
@ -2636,7 +2637,7 @@ 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. */
@ -2793,7 +2794,7 @@ 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);
@ -2809,13 +2810,12 @@ 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);
}
@ -2881,7 +2881,7 @@ 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);
@ -2972,7 +2972,7 @@ __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;
}
@ -3011,7 +3011,7 @@ __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
@ -3450,14 +3450,14 @@ 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;
}
@ -3564,7 +3564,7 @@ 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);
@ -3606,10 +3606,10 @@ 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. */
@ -3645,7 +3645,7 @@ 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);
@ -3665,7 +3665,7 @@ 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. */

93
kernel/rcu/tree_plugin.h
View file

@ -570,7 +570,7 @@ static int rcu_preempted_readers_exp(struct rcu_node *rnp)
static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
{
return !rcu_preempted_readers_exp(rnp) &&
ACCESS_ONCE(rnp->expmask) == 0;
READ_ONCE(rnp->expmask) == 0;
}
/*
@ -716,7 +716,7 @@ void synchronize_rcu_expedited(void)
int trycount = 0;
smp_mb(); /* Caller's modifications seen first by other CPUs. */
snap = ACCESS_ONCE(sync_rcu_preempt_exp_count) + 1;
snap = READ_ONCE(sync_rcu_preempt_exp_count) + 1;
smp_mb(); /* Above access cannot bleed into critical section. */
/*
@ -740,7 +740,7 @@ void synchronize_rcu_expedited(void)
*/
while (!mutex_trylock(&sync_rcu_preempt_exp_mutex)) {
if (ULONG_CMP_LT(snap,
ACCESS_ONCE(sync_rcu_preempt_exp_count))) {
READ_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto mb_ret; /* Others did our work for us. */
}
@ -752,7 +752,7 @@ void synchronize_rcu_expedited(void)
return;
}
}
if (ULONG_CMP_LT(snap, ACCESS_ONCE(sync_rcu_preempt_exp_count))) {
if (ULONG_CMP_LT(snap, READ_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto unlock_mb_ret; /* Others did our work for us. */
}
@ -780,8 +780,7 @@ void synchronize_rcu_expedited(void)
/* Clean up and exit. */
smp_mb(); /* ensure expedited GP seen before counter increment. */
ACCESS_ONCE(sync_rcu_preempt_exp_count) =
sync_rcu_preempt_exp_count + 1;
WRITE_ONCE(sync_rcu_preempt_exp_count, sync_rcu_preempt_exp_count + 1);
unlock_mb_ret:
mutex_unlock(&sync_rcu_preempt_exp_mutex);
mb_ret:
@ -994,8 +993,8 @@ static int rcu_boost(struct rcu_node *rnp)
struct task_struct *t;
struct list_head *tb;
if (ACCESS_ONCE(rnp->exp_tasks) == NULL &&
ACCESS_ONCE(rnp->boost_tasks) == NULL)
if (READ_ONCE(rnp->exp_tasks) == NULL &&
READ_ONCE(rnp->boost_tasks) == NULL)
return 0; /* Nothing left to boost. */
raw_spin_lock_irqsave(&rnp->lock, flags);
@ -1048,8 +1047,8 @@ static int rcu_boost(struct rcu_node *rnp)
rt_mutex_lock(&rnp->boost_mtx);
rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */
return ACCESS_ONCE(rnp->exp_tasks) != NULL ||
ACCESS_ONCE(rnp->boost_tasks) != NULL;
return READ_ONCE(rnp->exp_tasks) != NULL ||
READ_ONCE(rnp->boost_tasks) != NULL;
}
/*
@ -1462,7 +1461,7 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
* callbacks not yet ready to invoke.
*/
if ((rdp->completed != rnp->completed ||
unlikely(ACCESS_ONCE(rdp->gpwrap))) &&
unlikely(READ_ONCE(rdp->gpwrap))) &&
rdp->nxttail[RCU_DONE_TAIL] != rdp->nxttail[RCU_NEXT_TAIL])
note_gp_changes(rsp, rdp);
@ -1534,7 +1533,7 @@ static void rcu_prepare_for_idle(void)
int tne;
/* Handle nohz enablement switches conservatively. */
tne = ACCESS_ONCE(tick_nohz_active);
tne = READ_ONCE(tick_nohz_active);
if (tne != rdtp->tick_nohz_enabled_snap) {
if (rcu_cpu_has_callbacks(NULL))
invoke_rcu_core(); /* force nohz to see update. */
@ -1760,7 +1759,7 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
atomic_read(&rdtp->dynticks) & 0xfff,
rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
ACCESS_ONCE(rsp->n_force_qs) - rsp->n_force_qs_gpstart,
READ_ONCE(rsp->n_force_qs) - rsp->n_force_qs_gpstart,
fast_no_hz);
}
@ -1898,11 +1897,11 @@ static void wake_nocb_leader(struct rcu_data *rdp, bool force)
{
struct rcu_data *rdp_leader = rdp->nocb_leader;
if (!ACCESS_ONCE(rdp_leader->nocb_kthread))
if (!READ_ONCE(rdp_leader->nocb_kthread))
return;
if (ACCESS_ONCE(rdp_leader->nocb_leader_sleep) || force) {
if (READ_ONCE(rdp_leader->nocb_leader_sleep) || force) {
/* Prior smp_mb__after_atomic() orders against prior enqueue. */
ACCESS_ONCE(rdp_leader->nocb_leader_sleep) = false;
WRITE_ONCE(rdp_leader->nocb_leader_sleep, false);
wake_up(&rdp_leader->nocb_wq);
}
}
@ -1934,14 +1933,14 @@ static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
ret = atomic_long_read(&rdp->nocb_q_count);
#ifdef CONFIG_PROVE_RCU
rhp = ACCESS_ONCE(rdp->nocb_head);
rhp = READ_ONCE(rdp->nocb_head);
if (!rhp)
rhp = ACCESS_ONCE(rdp->nocb_gp_head);
rhp = READ_ONCE(rdp->nocb_gp_head);
if (!rhp)
rhp = ACCESS_ONCE(rdp->nocb_follower_head);
rhp = READ_ONCE(rdp->nocb_follower_head);
/* Having no rcuo kthread but CBs after scheduler starts is bad! */
if (!ACCESS_ONCE(rdp->nocb_kthread) && rhp &&
if (!READ_ONCE(rdp->nocb_kthread) && rhp &&
rcu_scheduler_fully_active) {
/* RCU callback enqueued before CPU first came online??? */
pr_err("RCU: Never-onlined no-CBs CPU %d has CB %p\n",
@ -1975,12 +1974,12 @@ static void __call_rcu_nocb_enqueue(struct rcu_data *rdp,
atomic_long_add(rhcount, &rdp->nocb_q_count);
/* rcu_barrier() relies on ->nocb_q_count add before xchg. */
old_rhpp = xchg(&rdp->nocb_tail, rhtp);
ACCESS_ONCE(*old_rhpp) = rhp;
WRITE_ONCE(*old_rhpp, rhp);
atomic_long_add(rhcount_lazy, &rdp->nocb_q_count_lazy);
smp_mb__after_atomic(); /* Store *old_rhpp before _wake test. */
/* If we are not being polled and there is a kthread, awaken it ... */
t = ACCESS_ONCE(rdp->nocb_kthread);
t = READ_ONCE(rdp->nocb_kthread);
if (rcu_nocb_poll || !t) {
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
TPS("WakeNotPoll"));
@ -2118,7 +2117,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
for (;;) {
wait_event_interruptible(
rnp->nocb_gp_wq[c & 0x1],
(d = ULONG_CMP_GE(ACCESS_ONCE(rnp->completed), c)));
(d = ULONG_CMP_GE(READ_ONCE(rnp->completed), c)));
if (likely(d))
break;
WARN_ON(signal_pending(current));
@ -2145,7 +2144,7 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
if (!rcu_nocb_poll) {
trace_rcu_nocb_wake(my_rdp->rsp->name, my_rdp->cpu, "Sleep");
wait_event_interruptible(my_rdp->nocb_wq,
!ACCESS_ONCE(my_rdp->nocb_leader_sleep));
!READ_ONCE(my_rdp->nocb_leader_sleep));
/* Memory barrier handled by smp_mb() calls below and repoll. */
} else if (firsttime) {
firsttime = false; /* Don't drown trace log with "Poll"! */
@ -2159,12 +2158,12 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
*/
gotcbs = false;
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower) {
rdp->nocb_gp_head = ACCESS_ONCE(rdp->nocb_head);
rdp->nocb_gp_head = READ_ONCE(rdp->nocb_head);
if (!rdp->nocb_gp_head)
continue; /* No CBs here, try next follower. */
/* Move callbacks to wait-for-GP list, which is empty. */
ACCESS_ONCE(rdp->nocb_head) = NULL;
WRITE_ONCE(rdp->nocb_head, NULL);
rdp->nocb_gp_tail = xchg(&rdp->nocb_tail, &rdp->nocb_head);
gotcbs = true;
}
@ -2184,7 +2183,7 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
my_rdp->nocb_leader_sleep = true;
smp_mb(); /* Ensure _sleep true before scan. */
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower)
if (ACCESS_ONCE(rdp->nocb_head)) {
if (READ_ONCE(rdp->nocb_head)) {
/* Found CB, so short-circuit next wait. */
my_rdp->nocb_leader_sleep = false;
break;
@ -2205,7 +2204,7 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
/* Each pass through the following loop wakes a follower, if needed. */
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower) {
if (ACCESS_ONCE(rdp->nocb_head))
if (READ_ONCE(rdp->nocb_head))
my_rdp->nocb_leader_sleep = false;/* No need to sleep.*/
if (!rdp->nocb_gp_head)
continue; /* No CBs, so no need to wake follower. */
@ -2241,7 +2240,7 @@ static void nocb_follower_wait(struct rcu_data *rdp)
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
"FollowerSleep");
wait_event_interruptible(rdp->nocb_wq,
ACCESS_ONCE(rdp->nocb_follower_head));
READ_ONCE(rdp->nocb_follower_head));
} else if (firsttime) {
/* Don't drown trace log with "Poll"! */
firsttime = false;
@ -2282,10 +2281,10 @@ static int rcu_nocb_kthread(void *arg)
nocb_follower_wait(rdp);
/* Pull the ready-to-invoke callbacks onto local list. */
list = ACCESS_ONCE(rdp->nocb_follower_head);
list = READ_ONCE(rdp->nocb_follower_head);
BUG_ON(!list);
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, "WokeNonEmpty");
ACCESS_ONCE(rdp->nocb_follower_head) = NULL;
WRITE_ONCE(rdp->nocb_follower_head, NULL);
tail = xchg(&rdp->nocb_follower_tail, &rdp->nocb_follower_head);
/* Each pass through the following loop invokes a callback. */
@ -2324,7 +2323,7 @@ static int rcu_nocb_kthread(void *arg)
/* Is a deferred wakeup of rcu_nocb_kthread() required? */
static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp)
{
return ACCESS_ONCE(rdp->nocb_defer_wakeup);
return READ_ONCE(rdp->nocb_defer_wakeup);
}
/* Do a deferred wakeup of rcu_nocb_kthread(). */
@ -2334,8 +2333,8 @@ static void do_nocb_deferred_wakeup(struct rcu_data *rdp)
if (!rcu_nocb_need_deferred_wakeup(rdp))
return;
ndw = ACCESS_ONCE(rdp->nocb_defer_wakeup);
ACCESS_ONCE(rdp->nocb_defer_wakeup) = RCU_NOGP_WAKE_NOT;
ndw = READ_ONCE(rdp->nocb_defer_wakeup);
WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOGP_WAKE_NOT);
wake_nocb_leader(rdp, ndw == RCU_NOGP_WAKE_FORCE);
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, TPS("DeferredWake"));
}
@ -2448,7 +2447,7 @@ static void rcu_spawn_one_nocb_kthread(struct rcu_state *rsp, int cpu)
t = kthread_run(rcu_nocb_kthread, rdp_spawn,
"rcuo%c/%d", rsp->abbr, cpu);
BUG_ON(IS_ERR(t));
ACCESS_ONCE(rdp_spawn->nocb_kthread) = t;
WRITE_ONCE(rdp_spawn->nocb_kthread, t);
}
/*
@ -2663,7 +2662,7 @@ static void rcu_sysidle_enter(int irq)
/* Record start of fully idle period. */
j = jiffies;
ACCESS_ONCE(rdtp->dynticks_idle_jiffies) = j;
WRITE_ONCE(rdtp->dynticks_idle_jiffies, j);
smp_mb__before_atomic();
atomic_inc(&rdtp->dynticks_idle);
smp_mb__after_atomic();
@ -2681,7 +2680,7 @@ static void rcu_sysidle_enter(int irq)
*/
void rcu_sysidle_force_exit(void)
{
int oldstate = ACCESS_ONCE(full_sysidle_state);
int oldstate = READ_ONCE(full_sysidle_state);
int newoldstate;
/*
@ -2794,7 +2793,7 @@ static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
smp_mb(); /* Read counters before timestamps. */
/* Pick up timestamps. */
j = ACCESS_ONCE(rdtp->dynticks_idle_jiffies);
j = READ_ONCE(rdtp->dynticks_idle_jiffies);
/* If this CPU entered idle more recently, update maxj timestamp. */
if (ULONG_CMP_LT(*maxj, j))
*maxj = j;
@ -2831,11 +2830,11 @@ static unsigned long rcu_sysidle_delay(void)
static void rcu_sysidle(unsigned long j)
{
/* Check the current state. */
switch (ACCESS_ONCE(full_sysidle_state)) {
switch (READ_ONCE(full_sysidle_state)) {
case RCU_SYSIDLE_NOT:
/* First time all are idle, so note a short idle period. */
ACCESS_ONCE(full_sysidle_state) = RCU_SYSIDLE_SHORT;
WRITE_ONCE(full_sysidle_state, RCU_SYSIDLE_SHORT);
break;
case RCU_SYSIDLE_SHORT:
@ -2873,7 +2872,7 @@ static void rcu_sysidle_cancel(void)
{
smp_mb();
if (full_sysidle_state > RCU_SYSIDLE_SHORT)
ACCESS_ONCE(full_sysidle_state) = RCU_SYSIDLE_NOT;
WRITE_ONCE(full_sysidle_state, RCU_SYSIDLE_NOT);
}
/*
@ -2925,7 +2924,7 @@ static void rcu_sysidle_cb(struct rcu_head *rhp)
smp_mb(); /* grace period precedes setting inuse. */
rshp = container_of(rhp, struct rcu_sysidle_head, rh);
ACCESS_ONCE(rshp->inuse) = 0;
WRITE_ONCE(rshp->inuse, 0);
}
/*
@ -2936,7 +2935,7 @@ static void rcu_sysidle_cb(struct rcu_head *rhp)
bool rcu_sys_is_idle(void)
{
static struct rcu_sysidle_head rsh;
int rss = ACCESS_ONCE(full_sysidle_state);
int rss = READ_ONCE(full_sysidle_state);
if (WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu))
return false;
@ -2964,7 +2963,7 @@ bool rcu_sys_is_idle(void)
}
rcu_sysidle_report(rcu_state_p, isidle, maxj, false);
oldrss = rss;
rss = ACCESS_ONCE(full_sysidle_state);
rss = READ_ONCE(full_sysidle_state);
}
}
@ -3048,7 +3047,7 @@ static bool rcu_nohz_full_cpu(struct rcu_state *rsp)
#ifdef CONFIG_NO_HZ_FULL
if (tick_nohz_full_cpu(smp_processor_id()) &&
(!rcu_gp_in_progress(rsp) ||
ULONG_CMP_LT(jiffies, ACCESS_ONCE(rsp->gp_start) + HZ)))
ULONG_CMP_LT(jiffies, READ_ONCE(rsp->gp_start) + HZ)))
return 1;
#endif /* #ifdef CONFIG_NO_HZ_FULL */
return 0;
@ -3077,7 +3076,7 @@ static void rcu_bind_gp_kthread(void)
static void rcu_dynticks_task_enter(void)
{
#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
ACCESS_ONCE(current->rcu_tasks_idle_cpu) = smp_processor_id();
WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id());
#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
}
@ -3085,6 +3084,6 @@ static void rcu_dynticks_task_enter(void)
static void rcu_dynticks_task_exit(void)
{
#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
ACCESS_ONCE(current->rcu_tasks_idle_cpu) = -1;
WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);
#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
}

6
kernel/rcu/tree_trace.c
View file

@ -277,7 +277,7 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
rsp->n_force_qs, rsp->n_force_qs_ngp,
rsp->n_force_qs - rsp->n_force_qs_ngp,
ACCESS_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
READ_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
if (rnp->level != level) {
seq_puts(m, "\n");
@ -323,8 +323,8 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
struct rcu_node *rnp = &rsp->node[0];
raw_spin_lock_irqsave(&rnp->lock, flags);
completed = ACCESS_ONCE(rsp->completed);
gpnum = ACCESS_ONCE(rsp->gpnum);
completed = READ_ONCE(rsp->completed);
gpnum = READ_ONCE(rsp->gpnum);
if (completed == gpnum)
gpage = 0;
else

30
kernel/rcu/update.c
View file

@ -150,14 +150,14 @@ void __rcu_read_unlock(void)
barrier(); /* critical section before exit code. */
t->rcu_read_lock_nesting = INT_MIN;
barrier(); /* assign before ->rcu_read_unlock_special load */
if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special.s)))
if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s)))
rcu_read_unlock_special(t);
barrier(); /* ->rcu_read_unlock_special load before assign */
t->rcu_read_lock_nesting = 0;
}
#ifdef CONFIG_PROVE_LOCKING
{
int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting);
int rrln = READ_ONCE(t->rcu_read_lock_nesting);
WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2);
}
@ -389,17 +389,17 @@ module_param(rcu_cpu_stall_timeout, int, 0644);
int rcu_jiffies_till_stall_check(void)
{
int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout);
int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout);
/*
* Limit check must be consistent with the Kconfig limits
* for CONFIG_RCU_CPU_STALL_TIMEOUT.
*/
if (till_stall_check < 3) {
ACCESS_ONCE(rcu_cpu_stall_timeout) = 3;
WRITE_ONCE(rcu_cpu_stall_timeout, 3);
till_stall_check = 3;
} else if (till_stall_check > 300) {
ACCESS_ONCE(rcu_cpu_stall_timeout) = 300;
WRITE_ONCE(rcu_cpu_stall_timeout, 300);
till_stall_check = 300;
}
return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
@ -550,12 +550,12 @@ static void check_holdout_task(struct task_struct *t,
{
int cpu;
if (!ACCESS_ONCE(t->rcu_tasks_holdout) ||
t->rcu_tasks_nvcsw != ACCESS_ONCE(t->nvcsw) ||
!ACCESS_ONCE(t->on_rq) ||
if (!READ_ONCE(t->rcu_tasks_holdout) ||
t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) ||
!READ_ONCE(t->on_rq) ||
(IS_ENABLED(CONFIG_NO_HZ_FULL) &&
!is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
ACCESS_ONCE(t->rcu_tasks_holdout) = false;
WRITE_ONCE(t->rcu_tasks_holdout, false);
list_del_init(&t->rcu_tasks_holdout_list);
put_task_struct(t);
return;
@ -639,11 +639,11 @@ static int __noreturn rcu_tasks_kthread(void *arg)
*/
rcu_read_lock();
for_each_process_thread(g, t) {
if (t != current && ACCESS_ONCE(t->on_rq) &&
if (t != current && READ_ONCE(t->on_rq) &&
!is_idle_task(t)) {
get_task_struct(t);
t->rcu_tasks_nvcsw = ACCESS_ONCE(t->nvcsw);
ACCESS_ONCE(t->rcu_tasks_holdout) = true;
t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw);
WRITE_ONCE(t->rcu_tasks_holdout, true);
list_add(&t->rcu_tasks_holdout_list,
&rcu_tasks_holdouts);
}
@ -672,7 +672,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
struct task_struct *t1;
schedule_timeout_interruptible(HZ);
rtst = ACCESS_ONCE(rcu_task_stall_timeout);
rtst = READ_ONCE(rcu_task_stall_timeout);
needreport = rtst > 0 &&
time_after(jiffies, lastreport + rtst);
if (needreport)
@ -728,7 +728,7 @@ static void rcu_spawn_tasks_kthread(void)
static struct task_struct *rcu_tasks_kthread_ptr;
struct task_struct *t;
if (ACCESS_ONCE(rcu_tasks_kthread_ptr)) {
if (READ_ONCE(rcu_tasks_kthread_ptr)) {
smp_mb(); /* Ensure caller sees full kthread. */
return;
}
@ -740,7 +740,7 @@ static void rcu_spawn_tasks_kthread(void)
t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
BUG_ON(IS_ERR(t));
smp_mb(); /* Ensure others see full kthread. */
ACCESS_ONCE(rcu_tasks_kthread_ptr) = t;
WRITE_ONCE(rcu_tasks_kthread_ptr, t);
mutex_unlock(&rcu_tasks_kthread_mutex);
}

26
kernel/torture.c
View file

@ -409,7 +409,7 @@ static void (*torture_shutdown_hook)(void);
*/
void torture_shutdown_absorb(const char *title)
{
while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
pr_notice("torture thread %s parking due to system shutdown\n",
title);
schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
@ -480,9 +480,9 @@ static int torture_shutdown_notify(struct notifier_block *unused1,
unsigned long unused2, void *unused3)
{
mutex_lock(&fullstop_mutex);
if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN;
WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
} else {
pr_warn("Concurrent rmmod and shutdown illegal!\n");
}
@ -523,13 +523,13 @@ static int stutter;
*/
void stutter_wait(const char *title)
{
while (ACCESS_ONCE(stutter_pause_test) ||
(torture_runnable && !ACCESS_ONCE(*torture_runnable))) {
while (READ_ONCE(stutter_pause_test) ||
(torture_runnable && !READ_ONCE(*torture_runnable))) {
if (stutter_pause_test)
if (ACCESS_ONCE(stutter_pause_test) == 1)
if (READ_ONCE(stutter_pause_test) == 1)
schedule_timeout_interruptible(1);
else
while (ACCESS_ONCE(stutter_pause_test))
while (READ_ONCE(stutter_pause_test))
cond_resched();
else
schedule_timeout_interruptible(round_jiffies_relative(HZ));
@ -549,14 +549,14 @@ static int torture_stutter(void *arg)
if (!torture_must_stop()) {
if (stutter > 1) {
schedule_timeout_interruptible(stutter - 1);
ACCESS_ONCE(stutter_pause_test) = 2;
WRITE_ONCE(stutter_pause_test, 2);
}
schedule_timeout_interruptible(1);
ACCESS_ONCE(stutter_pause_test) = 1;
WRITE_ONCE(stutter_pause_test, 1);
}
if (!torture_must_stop())
schedule_timeout_interruptible(stutter);
ACCESS_ONCE(stutter_pause_test) = 0;
WRITE_ONCE(stutter_pause_test, 0);
torture_shutdown_absorb("torture_stutter");
} while (!torture_must_stop());
torture_kthread_stopping("torture_stutter");
@ -642,13 +642,13 @@ EXPORT_SYMBOL_GPL(torture_init_end);
bool torture_cleanup_begin(void)
{
mutex_lock(&fullstop_mutex);
if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
pr_warn("Concurrent rmmod and shutdown illegal!\n");
mutex_unlock(&fullstop_mutex);
schedule_timeout_uninterruptible(10);
return true;
}
ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;
WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
mutex_unlock(&fullstop_mutex);
torture_shutdown_cleanup();
torture_shuffle_cleanup();
@ -681,7 +681,7 @@ EXPORT_SYMBOL_GPL(torture_must_stop);
*/
bool torture_must_stop_irq(void)
{
return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
}
EXPORT_SYMBOL_GPL(torture_must_stop_irq);