diff options
Diffstat (limited to 'spinlock.c')
| -rw-r--r-- | spinlock.c | 21 |
1 files changed, 15 insertions, 6 deletions
@@ -4,31 +4,39 @@ #include "mmu.h" #define LOCK_FREE -1 +#define DEBUG 0 uint32_t kernel_lock = LOCK_FREE; +int getcallerpc(void *v) { + return ((int*)v)[-1]; +} + // lock = LOCK_FREE if free, else = cpu_id of owner CPU -void +void acquire_spinlock(uint32_t* lock) { int cpu_id = cpu(); + // on a real machine there would be a memory barrier here + if(DEBUG) cprintf("cpu%d: acquiring at %x\n", cpu_id, getcallerpc(&lock)); + write_eflags(read_eflags() & ~FL_IF); if (*lock == cpu_id) - return; + panic("recursive lock"); - write_eflags(read_eflags() & ~FL_IF); while ( cmpxchg(LOCK_FREE, cpu_id, lock) != cpu_id ) { ; } - // cprintf ("acquired: %d\n", cpu_id); + if(DEBUG) cprintf("cpu%d: acquired at %x\n", cpu_id, getcallerpc(&lock)); } void release_spinlock(uint32_t* lock) { int cpu_id = cpu(); - // cprintf ("release: %d\n", cpu_id); + if(DEBUG) cprintf ("cpu%d: releasing at %x\n", cpu_id, getcallerpc(&lock)); if (*lock != cpu_id) panic("release_spinlock: releasing a lock that i don't own\n"); *lock = LOCK_FREE; + // on a real machine there would be a memory barrier here write_eflags(read_eflags() | FL_IF); } @@ -36,8 +44,9 @@ void release_grant_spinlock(uint32_t* lock, int c) { int cpu_id = cpu(); - // cprintf ("release_grant: %d -> %d\n", cpu_id, c); + if(DEBUG) cprintf ("cpu%d: release_grant to %d at %x\n", cpu_id, c, getcallerpc(&lock)); if (*lock != cpu_id) panic("release_spinlock: releasing a lock that i don't own\n"); *lock = c; } + |