Commit 284a8c93 authored by Paul E. McKenney's avatar Paul E. McKenney

rcu: Per-CPU operation cleanups to rcu_*_qs() functions

The rcu_bh_qs(), rcu_preempt_qs(), and rcu_sched_qs() functions use
old-style per-CPU variable access and write to ->passed_quiesce even
if it is already set.  This commit therefore updates to use the new-style
per-CPU variable access functions and avoids the spurious writes.
This commit also eliminates the "cpu" argument to these functions because
they are always invoked on the indicated CPU.
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 1d082fd0
......@@ -261,8 +261,8 @@ static inline int rcu_preempt_depth(void)
/* Internal to kernel */
void rcu_init(void);
void rcu_sched_qs(int cpu);
void rcu_bh_qs(int cpu);
void rcu_sched_qs(void);
void rcu_bh_qs(void);
void rcu_check_callbacks(int cpu, int user);
struct notifier_block;
void rcu_idle_enter(void);
......
......@@ -80,7 +80,7 @@ static inline void kfree_call_rcu(struct rcu_head *head,
static inline void rcu_note_context_switch(int cpu)
{
rcu_sched_qs(cpu);
rcu_sched_qs();
}
/*
......
......@@ -72,7 +72,7 @@ static void rcu_idle_enter_common(long long newval)
current->pid, current->comm,
idle->pid, idle->comm); /* must be idle task! */
}
rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
rcu_sched_qs(); /* implies rcu_bh_inc() */
barrier();
rcu_dynticks_nesting = newval;
}
......@@ -217,7 +217,7 @@ static int rcu_qsctr_help(struct rcu_ctrlblk *rcp)
* are at it, given that any rcu quiescent state is also an rcu_bh
* quiescent state. Use "+" instead of "||" to defeat short circuiting.
*/
void rcu_sched_qs(int cpu)
void rcu_sched_qs(void)
{
unsigned long flags;
......@@ -231,7 +231,7 @@ void rcu_sched_qs(int cpu)
/*
* Record an rcu_bh quiescent state.
*/
void rcu_bh_qs(int cpu)
void rcu_bh_qs(void)
{
unsigned long flags;
......@@ -251,9 +251,9 @@ void rcu_check_callbacks(int cpu, int user)
{
RCU_TRACE(check_cpu_stalls());
if (user || rcu_is_cpu_rrupt_from_idle())
rcu_sched_qs(cpu);
rcu_sched_qs();
else if (!in_softirq())
rcu_bh_qs(cpu);
rcu_bh_qs();
if (user)
rcu_note_voluntary_context_switch(current);
}
......
......@@ -188,22 +188,24 @@ static int rcu_gp_in_progress(struct rcu_state *rsp)
* one since the start of the grace period, this just sets a flag.
* The caller must have disabled preemption.
*/
void rcu_sched_qs(int cpu)
void rcu_sched_qs(void)
{
struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
if (rdp->passed_quiesce == 0)
trace_rcu_grace_period(TPS("rcu_sched"), rdp->gpnum, TPS("cpuqs"));
rdp->passed_quiesce = 1;
if (!__this_cpu_read(rcu_sched_data.passed_quiesce)) {
trace_rcu_grace_period(TPS("rcu_sched"),
__this_cpu_read(rcu_sched_data.gpnum),
TPS("cpuqs"));
__this_cpu_write(rcu_sched_data.passed_quiesce, 1);
}
}
void rcu_bh_qs(int cpu)
void rcu_bh_qs(void)
{
struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
if (rdp->passed_quiesce == 0)
trace_rcu_grace_period(TPS("rcu_bh"), rdp->gpnum, TPS("cpuqs"));
rdp->passed_quiesce = 1;
if (!__this_cpu_read(rcu_bh_data.passed_quiesce)) {
trace_rcu_grace_period(TPS("rcu_bh"),
__this_cpu_read(rcu_bh_data.gpnum),
TPS("cpuqs"));
__this_cpu_write(rcu_bh_data.passed_quiesce, 1);
}
}
static DEFINE_PER_CPU(int, rcu_sched_qs_mask);
......@@ -278,7 +280,7 @@ static void rcu_momentary_dyntick_idle(void)
void rcu_note_context_switch(int cpu)
{
trace_rcu_utilization(TPS("Start context switch"));
rcu_sched_qs(cpu);
rcu_sched_qs();
rcu_preempt_note_context_switch(cpu);
if (unlikely(raw_cpu_read(rcu_sched_qs_mask)))
rcu_momentary_dyntick_idle();
......@@ -2395,8 +2397,8 @@ void rcu_check_callbacks(int cpu, int user)
* at least not while the corresponding CPU is online.
*/
rcu_sched_qs(cpu);
rcu_bh_qs(cpu);
rcu_sched_qs();
rcu_bh_qs();
} else if (!in_softirq()) {
......@@ -2407,7 +2409,7 @@ void rcu_check_callbacks(int cpu, int user)
* critical section, so note it.
*/
rcu_bh_qs(cpu);
rcu_bh_qs();
}
rcu_preempt_check_callbacks(cpu);
if (rcu_pending(cpu))
......
......@@ -158,14 +158,16 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed);
* As with the other rcu_*_qs() functions, callers to this function
* must disable preemption.
*/
static void rcu_preempt_qs(int cpu)
{
struct rcu_data *rdp = &per_cpu(rcu_preempt_data, cpu);
if (rdp->passed_quiesce == 0)
trace_rcu_grace_period(TPS("rcu_preempt"), rdp->gpnum, TPS("cpuqs"));
rdp->passed_quiesce = 1;
current->rcu_read_unlock_special.b.need_qs = false;
static void rcu_preempt_qs(void)
{
if (!__this_cpu_read(rcu_preempt_data.passed_quiesce)) {
trace_rcu_grace_period(TPS("rcu_preempt"),
__this_cpu_read(rcu_preempt_data.gpnum),
TPS("cpuqs"));
__this_cpu_write(rcu_preempt_data.passed_quiesce, 1);
barrier(); /* Coordinate with rcu_preempt_check_callbacks(). */
current->rcu_read_unlock_special.b.need_qs = false;
}
}
/*
......@@ -256,7 +258,7 @@ static void rcu_preempt_note_context_switch(int cpu)
* grace period, then the fact that the task has been enqueued
* means that we continue to block the current grace period.
*/
rcu_preempt_qs(cpu);
rcu_preempt_qs();
}
/*
......@@ -352,7 +354,7 @@ void rcu_read_unlock_special(struct task_struct *t)
*/
special = t->rcu_read_unlock_special;
if (special.b.need_qs) {
rcu_preempt_qs(smp_processor_id());
rcu_preempt_qs();
if (!t->rcu_read_unlock_special.s) {
local_irq_restore(flags);
return;
......@@ -651,11 +653,12 @@ static void rcu_preempt_check_callbacks(int cpu)
struct task_struct *t = current;
if (t->rcu_read_lock_nesting == 0) {
rcu_preempt_qs(cpu);
rcu_preempt_qs();
return;
}
if (t->rcu_read_lock_nesting > 0 &&
per_cpu(rcu_preempt_data, cpu).qs_pending)
per_cpu(rcu_preempt_data, cpu).qs_pending &&
!per_cpu(rcu_preempt_data, cpu).passed_quiesce)
t->rcu_read_unlock_special.b.need_qs = true;
}
......
......@@ -278,7 +278,7 @@ asmlinkage __visible void __do_softirq(void)
pending >>= softirq_bit;
}
rcu_bh_qs(smp_processor_id());
rcu_bh_qs();
local_irq_disable();
pending = local_softirq_pending();
......
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