Imbus/xv6-riscv-kernel
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use asm() for lock release, not a C assignment

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Robert Morris 2016-09-08 14:45:20 -04:00
parent d63ac118e8
commit 34c2efc1d0
1 changed files with 4 additions and 2 deletions
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6
spinlock.c
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@ -59,8 +59,10 @@ release(struct spinlock *lk)
// stores; __sync_synchronize() tells them both to not re-order. // stores; __sync_synchronize() tells them both to not re-order.
__sync_synchronize(); __sync_synchronize();
// Release the lock. // Release the lock, equivalent to lk->locked = 0.
lk->locked = 0; // This code can't use a C assignment, since it might
// not be atomic.
asm volatile("movl $0, %0" : "+m" (lk->locked) : );
popcli(); popcli();
} }