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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: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Philipp Hachtmann 2014-04-07 18:25:23 +02:00 committed by Martin Schwidefsky
parent 5b3f683e69
commit 6c8cd5bbda
5 changed files with 21 additions and 10 deletions
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5
arch/s390/include/asm/lowcore.h
View File

@ -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 */

15
arch/s390/include/asm/spinlock.h
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@ -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)

4
arch/s390/kernel/setup.c
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@ -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;
}

3
arch/s390/kernel/smp.c
View File

@ -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);
}
/*

4
arch/s390/lib/spinlock.c
View File

@ -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);