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Commit 4ecf0a43 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

processor: get rid of cpu_relax_yield 



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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 38f2c691

arch/s390/include/asm/processor.h

+0 −6
Original line number Diff line number Diff line
@@ -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

arch/s390/kernel/processor.c

+2 −2
Original line number Diff line number Diff line
@@ -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.

include/linux/sched.h

+0 −4
Original line number Diff line number Diff line
@@ -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);

include/linux/stop_machine.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

kernel/stop_machine.c

+6 −1
Original line number Diff line number Diff line
@@ -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) {