95 lines
2.4 KiB
C
95 lines
2.4 KiB
C
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/* Low-priority main thread L acquires lock A. Medium-priority
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thread M then acquires lock B then blocks on acquiring lock A.
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High-priority thread H then blocks on acquiring lock B. Thus,
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thread H donates its priority to M, which in turn donates it
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to thread L.
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Based on a test originally submitted for Stanford's CS 140 in
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winter 1999 by Matt Franklin <startled@leland.stanford.edu>,
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Greg Hutchins <gmh@leland.stanford.edu>, Yu Ping Hu
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<yph@cs.stanford.edu>. Modified by arens. */
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#include <stdio.h>
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#include "tests/threads/tests.h"
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#include "threads/init.h"
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#include "threads/synch.h"
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#include "threads/thread.h"
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struct locks
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{
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struct lock *a;
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struct lock *b;
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};
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static thread_func medium_thread_func;
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static thread_func high_thread_func;
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void
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test_priority_donate_nest (void)
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{
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struct lock a, b;
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struct locks locks;
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/* This test does not work with the MLFQS. */
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ASSERT (!thread_mlfqs);
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/* Make sure our priority is the default. */
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ASSERT (thread_get_priority () == PRI_DEFAULT);
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lock_init (&a);
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lock_init (&b);
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lock_acquire (&a);
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locks.a = &a;
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locks.b = &b;
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thread_create ("medium", PRI_DEFAULT + 1, medium_thread_func, &locks);
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thread_yield ();
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msg ("Low thread should have priority %d. Actual priority: %d.",
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PRI_DEFAULT + 1, thread_get_priority ());
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thread_create ("high", PRI_DEFAULT + 2, high_thread_func, &b);
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thread_yield ();
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msg ("Low thread should have priority %d. Actual priority: %d.",
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PRI_DEFAULT + 2, thread_get_priority ());
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lock_release (&a);
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thread_yield ();
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msg ("Medium thread should just have finished.");
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msg ("Low thread should have priority %d. Actual priority: %d.",
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PRI_DEFAULT, thread_get_priority ());
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}
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static void
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medium_thread_func (void *locks_)
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{
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struct locks *locks = locks_;
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lock_acquire (locks->b);
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lock_acquire (locks->a);
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msg ("Medium thread should have priority %d. Actual priority: %d.",
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PRI_DEFAULT + 2, thread_get_priority ());
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msg ("Medium thread got the lock.");
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lock_release (locks->a);
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thread_yield ();
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lock_release (locks->b);
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thread_yield ();
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msg ("High thread should have just finished.");
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msg ("Middle thread finished.");
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}
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static void
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high_thread_func (void *lock_)
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{
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struct lock *lock = lock_;
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lock_acquire (lock);
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msg ("High thread got the lock.");
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lock_release (lock);
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msg ("High thread finished.");
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}
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