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

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This commit is contained in:
Balazs Gerofi
2018-02-07 19:27:33 +09:00
parent b08331b21a
commit 898708b8b4
1 changed files with 29 additions and 22 deletions
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51
arch/x86_64/kernel/include/arch-lock.h
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@@ -14,7 +14,17 @@
int __kprintf(const char *format, ...); int __kprintf(const char *format, ...);
#endif #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_enable(void);
extern void preempt_disable(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) 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 #ifdef DEBUG_SPINLOCK
#define ihk_mc_spinlock_lock_noirq(l) { \ #define ihk_mc_spinlock_lock_noirq(l) { \
@@ -37,29 +47,26 @@ __kprintf("[%d] ret ihk_mc_spinlock_lock_noirq\n", ihk_mc_get_processor_id()); \
#define ihk_mc_spinlock_lock_noirq __ihk_mc_spinlock_lock_noirq #define ihk_mc_spinlock_lock_noirq __ihk_mc_spinlock_lock_noirq
#endif #endif
static void __ihk_mc_spinlock_lock_noirq(ihk_spinlock_t *lock) static void __ihk_mc_spinlock_lock_noirq(ihk_spinlock_t *lock)
{ {
int inc = 0x00020000; register struct __raw_tickets inc = { .tail = 0x0002 };
int tmp;
preempt_disable(); preempt_disable();
asm volatile("lock; xaddl %0, %1\n" asm volatile ("lock xaddl %0, %1\n"
"movzwl %w0, %2\n\t" : "+r" (inc), "+m" (*(lock)) : : "memory", "cc");
"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");
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 #ifdef DEBUG_SPINLOCK
@@ -93,10 +100,10 @@ __kprintf("[%d] ret ihk_mc_spinlock_unlock_noirq\n", ihk_mc_get_processor_id());
#endif #endif
static void __ihk_mc_spinlock_unlock_noirq(ihk_spinlock_t *lock) static void __ihk_mc_spinlock_unlock_noirq(ihk_spinlock_t *lock)
{ {
int inc = 0x0002; __ticket_t inc = 0x0002;
asm volatile ("lock addw %1, %0\n" asm volatile ("lock addw %1, %0\n"
: "+m" (*(lock)) : "ri" (inc) : "memory", "cc"); : "+m" (lock->tickets.head) : "ri" (inc) : "memory", "cc");
preempt_enable(); preempt_enable();
} }