83 lines
1.9 KiB
C
83 lines
1.9 KiB
C
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/* Low priority thread L acquires a lock, then blocks downing a
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semaphore. Medium priority thread M then blocks waiting on
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the same semaphore. Next, high priority thread H attempts to
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acquire the lock, donating its priority to L.
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Next, the main thread ups the semaphore, waking up L. L
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releases the lock, which wakes up H. H "up"s the semaphore,
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waking up M. H terminates, then M, then L, and finally the
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main thread.
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Written by Godmar Back <gback@cs.vt.edu>. */
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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 lock_and_sema
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{
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struct lock lock;
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struct semaphore sema;
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};
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static thread_func l_thread_func;
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static thread_func m_thread_func;
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static thread_func h_thread_func;
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void
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test_priority_donate_sema (void)
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{
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struct lock_and_sema ls;
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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 (&ls.lock);
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sema_init (&ls.sema, 0);
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thread_create ("low", PRI_DEFAULT + 1, l_thread_func, &ls);
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thread_create ("med", PRI_DEFAULT + 3, m_thread_func, &ls);
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thread_create ("high", PRI_DEFAULT + 5, h_thread_func, &ls);
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sema_up (&ls.sema);
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msg ("Main thread finished.");
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}
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static void
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l_thread_func (void *ls_)
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{
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struct lock_and_sema *ls = ls_;
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lock_acquire (&ls->lock);
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msg ("Thread L acquired lock.");
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sema_down (&ls->sema);
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msg ("Thread L downed semaphore.");
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lock_release (&ls->lock);
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msg ("Thread L finished.");
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}
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static void
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m_thread_func (void *ls_)
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{
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struct lock_and_sema *ls = ls_;
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sema_down (&ls->sema);
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msg ("Thread M finished.");
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}
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static void
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h_thread_func (void *ls_)
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{
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struct lock_and_sema *ls = ls_;
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lock_acquire (&ls->lock);
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msg ("Thread H acquired lock.");
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sema_up (&ls->sema);
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lock_release (&ls->lock);
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msg ("Thread H finished.");
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}
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