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Back out part of previous commit (even though it's technically correct).

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Our spinlock implementation allows a particular thread to obtain a lock
multiple times, but release the lock with a single unlock call.  Since
we're detecting recursion, we know the lock is already owned by the
current thread in a previous call and must not be released in the
current call.  This is really far too dependent on this particular
spinlock implementation, so I've added commented out calls to
THREAD_UNLOCK in the appropriate places.  We can activate this code when
spinlock is taught to count each lock operation.
This commit is contained in:
Alexander Langer 1998-09-20 01:07:50 +00:00
parent 89f1cf1c51
commit d988805a1f
1 changed files with 17 additions and 1 deletions
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18
lib/libc/stdlib/malloc.c
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@ -6,7 +6,7 @@
* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
* ----------------------------------------------------------------------------
*
* $Id: malloc.c,v 1.39 1998/06/18 09:13:16 peter Exp $
* $Id: malloc.c,v 1.40 1998/09/19 20:55:36 alex Exp $
*
*/
@ -1064,6 +1064,7 @@ malloc(size_t size)
if (malloc_active++) {
wrtwarning("recursive call.\n");
malloc_active--;
/*THREAD_UNLOCK();*/ /* XXX */
return (0);
}
if (!malloc_started)
@ -1087,6 +1088,20 @@ free(void *ptr)
malloc_func = " in free():";
if (malloc_active++) {
wrtwarning("recursive call.\n");
/*
* XXX
* Ideally the next two lines would be gone and free() would
* exit below. Unfortunately our spinlock implementation
* allows a particular thread to obtain a lock multiple times
* without counting how many times said operation has been
* performed. The practical upshot of which is a single unlock
* causes all locks to be undone at once. For this reason,
* we return without performing an unlock in the case of
* recursion (see also the commented out THREAD_UNLOCK calls
* in malloc & realloc).
*/
malloc_active--;
return;
} else {
ifree(ptr);
UTRACE(ptr, 0, 0);
@ -1106,6 +1121,7 @@ realloc(void *ptr, size_t size)
if (malloc_active++) {
wrtwarning("recursive call.\n");
malloc_active--;
/*THREAD_UNLOCK();*/ /* XXX */
return (0);
}
if (ptr && !malloc_started) {