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spinlock: rewrite spinlock to use Linux ticket head/tail format

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This is a cherry-pick of 2964302d094f035242d6257d8af5450f72f9b5a7.

Change-Id: Ie8b7e825b28415dd41cc232fbeceb4653251f9e3
This commit is contained in:
Balazs Gerofi
2018-02-07 19:27:33 +09:00
committed by Masamichi Takagi
parent 0bcd3d5de3
commit ff383d96ba
1 changed files with 32 additions and 35 deletions
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65
arch/x86_64/kernel/include/arch-lock.h
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@ -14,7 +14,17 @@
int __kprintf(const char *format, ...);
#endif
typedef int ihk_spinlock_t;
typedef unsigned short __ticket_t;
typedef unsigned int __ticketpair_t;
typedef struct ihk_spinlock {
union {
__ticketpair_t head_tail;
struct __raw_tickets {
__ticket_t head, tail;
} tickets;
};
} ihk_spinlock_t;
extern void preempt_enable(void);
extern void preempt_disable(void);
@ -23,9 +33,9 @@ extern void preempt_disable(void);
static void ihk_mc_spinlock_init(ihk_spinlock_t *lock)
{
*lock = 0;
lock->head_tail = 0;
}
#define SPIN_LOCK_UNLOCKED 0
#define SPIN_LOCK_UNLOCKED { .head_tail = 0 }
#ifdef DEBUG_SPINLOCK
#define ihk_mc_spinlock_lock_noirq(l) { \
@ -39,40 +49,24 @@ __kprintf("[%d] ret ihk_mc_spinlock_lock_noirq\n", ihk_mc_get_processor_id()); \
static void __ihk_mc_spinlock_lock_noirq(ihk_spinlock_t *lock)
{
int inc = 0x00010000;
int tmp;
#if 0
asm volatile("lock ; xaddl %0, %1\n"
"movzwl %w0, %2\n\t"
"shrl $16, %0\n\t"
"1:\t"
"cmpl %0, %2\n\t"
"je 2f\n\t"
"rep ; nop\n\t"
"movzwl %1, %2\n\t"
"jmp 1b\n"
"2:"
: "+Q" (inc), "+m" (*lock), "=r" (tmp) : : "memory", "cc");
#endif
register struct __raw_tickets inc = { .tail = 0x0002 };
preempt_disable();
asm volatile("lock; xaddl %0, %1\n"
"movzwl %w0, %2\n\t"
"shrl $16, %0\n\t"
"1:\t"
"cmpl %0, %2\n\t"
"je 2f\n\t"
"rep ; nop\n\t"
"movzwl %1, %2\n\t"
/* don't need lfence here, because loads are in-order */
"jmp 1b\n"
"2:"
: "+r" (inc), "+m" (*lock), "=&r" (tmp)
:
: "memory", "cc");
asm volatile ("lock xaddl %0, %1\n"
: "+r" (inc), "+m" (*(lock)) : : "memory", "cc");
if (inc.head == inc.tail)
goto out;
for (;;) {
if (*((volatile __ticket_t *)&lock->tickets.head) == inc.tail)
goto out;
cpu_pause();
}
out:
barrier(); /* make sure nothing creeps before the lock is taken */
}
#ifdef DEBUG_SPINLOCK
@ -106,7 +100,10 @@ __kprintf("[%d] ret ihk_mc_spinlock_unlock_noirq\n", ihk_mc_get_processor_id());
#endif
static void __ihk_mc_spinlock_unlock_noirq(ihk_spinlock_t *lock)
{
asm volatile ("lock incw %0" : "+m"(*lock) : : "memory", "cc");
__ticket_t inc = 0x0002;
asm volatile ("lock addw %1, %0\n"
: "+m" (lock->tickets.head) : "ri" (inc) : "memory", "cc");
preempt_enable();
}