Commit 6c8cd5bb authored by Philipp Hachtmann's avatar Philipp Hachtmann Committed by Martin Schwidefsky
Browse files

s390/spinlock: optimize spinlock code sequence 



Use lowcore constant to improve the code generated for spinlocks.

[ Martin Schwidefsky: patch breakdown and code beautification ]

Signed-off-by: default avatarPhilipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 5b3f683e

arch/s390/include/asm/lowcore.h

+3 −2
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ struct _lowcore { 
	__u32	percpu_offset;			/* 0x02f0 */

	__u32	machine_flags;			/* 0x02f4 */

	__u32	ftrace_func;			/* 0x02f8 */

	__u8	pad_0x02fc[0x0300-0x02fc];	/* 0x02fc */

	__u32	spinlock_lockval;		/* 0x02fc */



	/* Interrupt response block */

	__u8	irb[64];			/* 0x0300 */
@@ -285,7 +285,8 @@ struct _lowcore { 
	__u64	machine_flags;			/* 0x0388 */

	__u64	ftrace_func;			/* 0x0390 */

	__u64	gmap;				/* 0x0398 */

	__u8	pad_0x03a0[0x0400-0x03a0];	/* 0x03a0 */

	__u32	spinlock_lockval;		/* 0x03a0 */

	__u8	pad_0x03a0[0x0400-0x03a4];	/* 0x03a4 */



	/* Interrupt response block. */

	__u8	irb[64];			/* 0x0400 */

arch/s390/include/asm/spinlock.h

+9 −6
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ 


#include <linux/smp.h>



#define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)



extern int spin_retry;



static inline int
@@ -40,6 +42,11 @@ int arch_spin_trylock_retry(arch_spinlock_t *); 
void arch_spin_relax(arch_spinlock_t *);

void arch_spin_lock_wait_flags(arch_spinlock_t *, unsigned long flags);



static inline u32 arch_spin_lockval(int cpu)

{

	return ~cpu;

}



static inline int arch_spin_value_unlocked(arch_spinlock_t lock)

{

	return lock.lock == 0;
@@ -52,16 +59,12 @@ static inline int arch_spin_is_locked(arch_spinlock_t *lp) 


static inline int arch_spin_trylock_once(arch_spinlock_t *lp)

{

	unsigned int new = ~smp_processor_id();



	return _raw_compare_and_swap(&lp->lock, 0, new);

	return _raw_compare_and_swap(&lp->lock, 0, SPINLOCK_LOCKVAL);

}



static inline int arch_spin_tryrelease_once(arch_spinlock_t *lp)

{

	unsigned int old = ~smp_processor_id();



	return _raw_compare_and_swap(&lp->lock, old, 0);

	return _raw_compare_and_swap(&lp->lock, SPINLOCK_LOCKVAL, 0);

}



static inline void arch_spin_lock(arch_spinlock_t *lp)

arch/s390/kernel/setup.c

+4 −0
Original line number Diff line number Diff line
@@ -373,6 +373,10 @@ static void __init setup_lowcore(void) 
	mem_assign_absolute(S390_lowcore.restart_source, lc->restart_source);

	mem_assign_absolute(S390_lowcore.restart_psw, lc->restart_psw);



#ifdef CONFIG_SMP

	lc->spinlock_lockval = arch_spin_lockval(0);

#endif



	set_prefix((u32)(unsigned long) lc);

	lowcore_ptr[0] = lc;

}

arch/s390/kernel/smp.c

+3 −0
Original line number Diff line number Diff line
@@ -170,6 +170,7 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu) 
	lc->panic_stack = pcpu->panic_stack + PAGE_SIZE

		- STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);

	lc->cpu_nr = cpu;

	lc->spinlock_lockval = arch_spin_lockval(cpu);

#ifndef CONFIG_64BIT

	if (MACHINE_HAS_IEEE) {

		lc->extended_save_area_addr = get_zeroed_page(GFP_KERNEL);
@@ -226,6 +227,7 @@ static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu) 
	cpumask_set_cpu(cpu, mm_cpumask(&init_mm));

	atomic_inc(&init_mm.context.attach_count);

	lc->cpu_nr = cpu;

	lc->spinlock_lockval = arch_spin_lockval(cpu);

	lc->percpu_offset = __per_cpu_offset[cpu];

	lc->kernel_asce = S390_lowcore.kernel_asce;

	lc->machine_flags = S390_lowcore.machine_flags;
@@ -809,6 +811,7 @@ void __init smp_cpus_done(unsigned int max_cpus) 
void __init smp_setup_processor_id(void)

{

	S390_lowcore.cpu_nr = 0;

	S390_lowcore.spinlock_lockval = arch_spin_lockval(0);

}



/*

arch/s390/lib/spinlock.c

+2 −2
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ __setup("spin_retry=", spin_retry_setup); 
void arch_spin_lock_wait(arch_spinlock_t *lp)

{

	int count = spin_retry;

	unsigned int cpu = ~smp_processor_id();

	unsigned int cpu = SPINLOCK_LOCKVAL;

	unsigned int owner;



	while (1) {
@@ -54,7 +54,7 @@ EXPORT_SYMBOL(arch_spin_lock_wait); 
void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)

{

	int count = spin_retry;

	unsigned int cpu = ~smp_processor_id();

	unsigned int cpu = SPINLOCK_LOCKVAL;

	unsigned int owner;



	local_irq_restore(flags);