* [PATCH v2 tip/core/rcu 2/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rcupdate.h
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 3/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rcutorture.c Paul E. McKenney
` (6 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves include/linux/rcupdate.h 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>
---
include/linux/rcupdate.h | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 573a5afd5ed8..87bb0eee665b 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -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
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 3/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rcutorture.c
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 2/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rcupdate.h Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 4/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in srcu.c Paul E. McKenney
` (5 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves kernel/rcu/rcutorture.c 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>
---
kernel/rcu/rcutorture.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 8dbe27611ec3..a67ef6ff86b0 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -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(). */
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 4/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in srcu.c
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 2/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rcupdate.h Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 3/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rcutorture.c Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 5/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tiny_plugin.h Paul E. McKenney
` (4 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves kernel/rcu/srcu.c 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>
---
kernel/rcu/srcu.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
index cad76e76b4e7..fb33d35ee0b7 100644
--- a/kernel/rcu/srcu.c
+++ b/kernel/rcu/srcu.c
@@ -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. */
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 5/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tiny_plugin.h
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
` (2 preceding siblings ...)
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 4/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in srcu.c Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 6/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree.c Paul E. McKenney
` (3 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves kernel/rcu/tiny_plugin.h 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>
---
kernel/rcu/tiny_plugin.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h
index f94e209a10d6..e492a5253e0f 100644
--- a/kernel/rcu/tiny_plugin.h
+++ b/kernel/rcu/tiny_plugin.h
@@ -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)
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 6/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree.c
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
` (3 preceding siblings ...)
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 5/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tiny_plugin.h Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 7/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree_plugin.h Paul E. McKenney
` (2 subsequent siblings)
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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@linux.vnet.ibm.com>
---
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
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 7/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree_plugin.h
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
` (4 preceding siblings ...)
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 6/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree.c Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 8/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree_trace.c Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 9/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in update.c Paul E. McKenney
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves kernel/rcu/tree_plugin.h 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>
---
kernel/rcu/tree_plugin.h | 93 ++++++++++++++++++++++++------------------------
1 file changed, 46 insertions(+), 47 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 564360e35fa7..8f8142778684 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -574,7 +574,7 @@ 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;
}
/*
@@ -720,7 +720,7 @@ 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. */
/*
@@ -744,7 +744,7 @@ 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. */
}
@@ -756,7 +756,7 @@ 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. */
}
@@ -784,8 +784,7 @@ 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:
@@ -998,8 +997,8 @@ 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);
@@ -1052,8 +1051,8 @@ 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;
}
/*
@@ -1466,7 +1465,7 @@ 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);
@@ -1538,7 +1537,7 @@ 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. */
@@ -1764,7 +1763,7 @@ 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);
}
@@ -1902,11 +1901,11 @@ 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);
}
}
@@ -1938,14 +1937,14 @@ 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",
@@ -1979,12 +1978,12 @@ 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"));
@@ -2122,7 +2121,7 @@ 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));
@@ -2149,7 +2148,7 @@ wait_again:
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"! */
@@ -2163,12 +2162,12 @@ wait_again:
*/
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;
}
@@ -2188,7 +2187,7 @@ wait_again:
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;
@@ -2209,7 +2208,7 @@ wait_again:
/* 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. */
@@ -2245,7 +2244,7 @@ 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;
@@ -2286,10 +2285,10 @@ 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. */
@@ -2328,7 +2327,7 @@ 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(). */
@@ -2338,8 +2337,8 @@ 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"));
}
@@ -2452,7 +2451,7 @@ 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);
}
/*
@@ -2667,7 +2666,7 @@ 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();
@@ -2685,7 +2684,7 @@ 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;
/*
@@ -2798,7 +2797,7 @@ 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;
@@ -2835,11 +2834,11 @@ 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:
@@ -2877,7 +2876,7 @@ 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);
}
/*
@@ -2929,7 +2928,7 @@ 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);
}
/*
@@ -2940,7 +2939,7 @@ 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;
@@ -2968,7 +2967,7 @@ 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);
}
}
@@ -3052,7 +3051,7 @@ 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;
@@ -3081,7 +3080,7 @@ 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) */
}
@@ -3089,6 +3088,6 @@ 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) */
}
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 8/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree_trace.c
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
` (5 preceding siblings ...)
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 7/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree_plugin.h Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 9/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in update.c Paul E. McKenney
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves kernel/rcu/tree_trace.c 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>
---
kernel/rcu/tree_trace.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index f92361efd0f5..3ea7ffc7d5c4 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -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
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCH v2 tip/core/rcu 9/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in update.c
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 1/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in rculist.h Paul E. McKenney
` (6 preceding siblings ...)
2015-03-16 18:42 ` [PATCH v2 tip/core/rcu 8/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in tree_trace.c Paul E. McKenney
@ 2015-03-16 18:42 ` Paul E. McKenney
7 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-03-16 18:42 UTC (permalink / raw)
To: linux-kernel
Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, tglx,
peterz, rostedt, dhowells, edumazet, dvhart, fweisbec, oleg,
bobby.prani, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
This commit moves kernel/rcu/update.c 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>
---
kernel/rcu/update.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 1f133350da01..afaecb7a799a 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -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);
}
--
1.8.1.5
^ permalink raw reply related [flat|nested] 13+ messages in thread