65 lines
775 B
C
65 lines
775 B
C
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#include <u.h>
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#include <libc.h>
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int
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canlock(Lock *lk)
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{
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return !tas(&lk->key);
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}
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void
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lock(Lock *lk)
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{
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int i;
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/* easy case */
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if(canlock(lk))
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return;
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/* for multi processor machines */
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for(i=0; i<100; i++)
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if(canlock(lk))
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return;
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for(i=0; i<100; i++) {
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osyield(0);
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if(canlock(lk))
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return;
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}
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/* looking bad - make sure it is not a priority problem */
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for(i=0; i<12; i++) {
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osmsleep(1<<i);
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if(canlock(lk))
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return;
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}
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/* we are in trouble */
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for(;;) {
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if(canlock(lk))
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return;
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iprint("lock loop %ld: val=%d &lock=%ux pc=%ux\n", getpid(), lk->key, lk, getcallerpc(&lk));
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osmsleep(1000);
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}
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}
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void
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unlock(Lock *lk)
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{
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assert(lk->key);
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lk->key = 0;
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}
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void
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ilock(Lock *lk)
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{
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lock(lk);
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}
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void
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iunlock(Lock *lk)
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{
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unlock(lk);
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}
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