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Fix donate_priority to disable interrupts for entire update of possibly-ready donatee's priority

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Themis Demetriades
2024-10-23 14:10:48 +01:00
parent b0074c80f0
commit 5f8dea21be
1 changed files with 6 additions and 4 deletions
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8
src/threads/synch.c
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@@ -210,25 +210,27 @@ donate_priority (struct thread *donee) {
if (donor->priority <= donee->priority) if (donor->priority <= donee->priority)
break; break;
donee->priority = donor->priority;
/* Also stop propagation of donation once a donee is reached with /* Also stop propagation of donation once a donee is reached with
no donees of its own (sink node in WFG). */ no donees of its own (sink node in WFG). */
if (donee->waiting_lock == NULL) if (donee->waiting_lock == NULL)
{ {
/* Only the sink node of the WFG isn't waiting for a lock and /* Only the sink node of the WFG isn't waiting for a lock and
could be on the ready list. Thus, as its priority changed, could be on the ready list. Thus, as its priority changed,
it must be reinserted into the list. */ it must be reinserted into the list. */
enum intr_level old_level = intr_disable (); enum intr_level old_level = intr_disable ();
donee->priority = donor->priority;
ready_list_reinsert (donee); ready_list_reinsert (donee);
intr_set_level (old_level); intr_set_level (old_level);
donee = NULL; donee = NULL;
} }
else else
{
donee->priority = donor->priority;
donee = donee->waiting_lock->holder; donee = donee->waiting_lock->holder;
} }
} }
}
/* Acquires LOCK, sleeping until it becomes available if /* Acquires LOCK, sleeping until it becomes available if
necessary. The lock must not already be held by the current necessary. The lock must not already be held by the current