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processor: get rid of cpu_relax_yield

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stop_machine is the only user left of cpu_relax_yield. Given that it
now has special semantics which are tied to stop_machine introduce a
weak stop_machine_yield function which architectures can override, and
get rid of the generic cpu_relax_yield implementation.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
This commit is contained in:
Heiko Carstens 2019-06-08 12:13:57 +02:00
parent 38f2c691a4
commit 4ecf0a43e7
5 changed files with 9 additions and 13 deletions
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6
arch/s390/include/asm/processor.h
View File

@ -222,12 +222,6 @@ static __no_kasan_or_inline unsigned short stap(void)
return cpu_address;
}
/*
* Give up the time slice of the virtual PU.
*/
#define cpu_relax_yield cpu_relax_yield
void cpu_relax_yield(const struct cpumask *cpumask);
#define cpu_relax() barrier()
#define ECAG_CACHE_ATTRIBUTE 0

4
arch/s390/kernel/processor.c
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@ -7,6 +7,7 @@
#define KMSG_COMPONENT "cpu"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/stop_machine.h>
#include <linux/cpufeature.h>
#include <linux/bitops.h>
#include <linux/kernel.h>
@ -59,7 +60,7 @@ void s390_update_cpu_mhz(void)
on_each_cpu(update_cpu_mhz, NULL, 0);
}
void notrace cpu_relax_yield(const struct cpumask *cpumask)
void notrace stop_machine_yield(const struct cpumask *cpumask)
{
int cpu, this_cpu;
@ -73,7 +74,6 @@ void notrace cpu_relax_yield(const struct cpumask *cpumask)
smp_yield_cpu(cpu);
}
}
EXPORT_SYMBOL(cpu_relax_yield);
/*
* cpu_init - initializes state that is per-CPU.

4
include/linux/sched.h
View File

@ -1518,10 +1518,6 @@ static inline int set_cpus_allowed_ptr(struct task_struct *p, const struct cpuma
}
#endif
#ifndef cpu_relax_yield
#define cpu_relax_yield(cpumask) cpu_relax()
#endif
extern int yield_to(struct task_struct *p, bool preempt);
extern void set_user_nice(struct task_struct *p, long nice);
extern int task_prio(const struct task_struct *p);

1
include/linux/stop_machine.h
View File

@ -36,6 +36,7 @@ int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
void stop_machine_park(int cpu);
void stop_machine_unpark(int cpu);
void stop_machine_yield(const struct cpumask *cpumask);
#else /* CONFIG_SMP */

7
kernel/stop_machine.c
View File

@ -177,6 +177,11 @@ static void ack_state(struct multi_stop_data *msdata)
set_state(msdata, msdata->state + 1);
}
void __weak stop_machine_yield(const struct cpumask *cpumask)
{
cpu_relax();
}
/* This is the cpu_stop function which stops the CPU. */
static int multi_cpu_stop(void *data)
{
@ -204,7 +209,7 @@ static int multi_cpu_stop(void *data)
/* Simple state machine */
do {
/* Chill out and ensure we re-read multi_stop_state. */
cpu_relax_yield(cpumask);
stop_machine_yield(cpumask);
if (msdata->state != curstate) {
curstate = msdata->state;
switch (curstate) {