52 lines
1.2 KiB
C
52 lines
1.2 KiB
C
#include "types.h"
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#include "defs.h"
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#include "x86.h"
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#include "mmu.h"
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#define LOCK_FREE -1
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#define DEBUG 0
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uint32_t kernel_lock = LOCK_FREE;
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int getcallerpc(void *v) {
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return ((int*)v)[-1];
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}
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// lock = LOCK_FREE if free, else = cpu_id of owner CPU
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void
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acquire_spinlock(uint32_t* lock)
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{
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int cpu_id = cpu();
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// on a real machine there would be a memory barrier here
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if(DEBUG) cprintf("cpu%d: acquiring at %x\n", cpu_id, getcallerpc(&lock));
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cli();
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if (*lock == cpu_id)
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panic("recursive lock");
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while ( cmpxchg(LOCK_FREE, cpu_id, lock) != cpu_id ) { ; }
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if(DEBUG) cprintf("cpu%d: acquired at %x\n", cpu_id, getcallerpc(&lock));
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}
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void
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release_spinlock(uint32_t* lock)
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{
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int cpu_id = cpu();
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if(DEBUG) cprintf ("cpu%d: releasing at %x\n", cpu_id, getcallerpc(&lock));
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if (*lock != cpu_id)
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panic("release_spinlock: releasing a lock that i don't own\n");
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*lock = LOCK_FREE;
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// on a real machine there would be a memory barrier here
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sti();
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}
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void
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release_grant_spinlock(uint32_t* lock, int c)
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{
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int cpu_id = cpu();
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if(DEBUG) cprintf ("cpu%d: release_grant to %d at %x\n", cpu_id, c, getcallerpc(&lock));
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if (*lock != cpu_id)
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panic("release_spinlock: releasing a lock that i don't own\n");
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*lock = c;
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}
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