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

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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: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2014-08-14 16:38:46 -07:00
parent 1d082fd061
commit 284a8c93af
6 changed files with 41 additions and 36 deletions
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34
kernel/rcu/tree.c
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@@ -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))