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Get rid of kmalloc()

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This changes *NSYNC to allocate waiters on the stack so our locks don't
need to depend on dynamic memory. This make our runtiem simpler, and it
also fixes bugs with thread cancellation support.
This commit is contained in:
Justine Tunney 2023-09-11 21:34:53 -07:00
parent 77a7873057
commit a359de7893
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GPG key ID: BE714B4575D6E328
57 changed files with 405 additions and 472 deletions
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17
third_party/nsync/mu.c vendored
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@ -103,7 +103,8 @@ void nsync_mu_lock_slow_ (nsync_mu *mu, waiter *w, uint32_t clear, lock_type *l_
/* wait until awoken. */
while (ATM_LOAD_ACQ (&w->nw.waiting) != 0) { /* acquire load */
nsync_mu_semaphore_p (&w->sem);
/* This can only return 0 or ECANCELED. */
ASSERT (nsync_mu_semaphore_p (&w->sem) == 0);
}
wait_count++;
/* If the thread has been woken more than this many
@ -155,9 +156,10 @@ void nsync_mu_lock (nsync_mu *mu) {
if ((old_word&MU_WZERO_TO_ACQUIRE) != 0 ||
!ATM_CAS_ACQ (&mu->word, old_word,
(old_word+MU_WADD_TO_ACQUIRE) & ~MU_WCLEAR_ON_ACQUIRE)) {
waiter *w = nsync_waiter_new_ ();
nsync_mu_lock_slow_ (mu, w, 0, nsync_writer_type_);
nsync_waiter_free_ (w);
waiter w;
nsync_waiter_init_ (&w);
nsync_mu_lock_slow_ (mu, &w, 0, nsync_writer_type_);
nsync_waiter_destroy_ (&w);
}
}
IGNORE_RACES_END ();
@ -190,9 +192,10 @@ void nsync_mu_rlock (nsync_mu *mu) {
if ((old_word&MU_RZERO_TO_ACQUIRE) != 0 ||
!ATM_CAS_ACQ (&mu->word, old_word,
(old_word+MU_RADD_TO_ACQUIRE) & ~MU_RCLEAR_ON_ACQUIRE)) {
waiter *w = nsync_waiter_new_ ();
nsync_mu_lock_slow_ (mu, w, 0, nsync_reader_type_);
nsync_waiter_free_ (w);
waiter w;
nsync_waiter_init_ (&w);
nsync_mu_lock_slow_ (mu, &w, 0, nsync_reader_type_);
nsync_waiter_destroy_ (&w);
}
}
IGNORE_RACES_END ();