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[pintos-anon]
/
src
/
threads
/
palloc.c
diff --git
a/src/threads/palloc.c
b/src/threads/palloc.c
index a25c09e0715d3140ff3f122f051aff0539693daa..2b07ad769c139ff3f7f661980936fbde0e6eea5e 100644
(file)
--- a/
src/threads/palloc.c
+++ b/
src/threads/palloc.c
@@
-58,6
+58,10
@@
palloc_init (void)
list_init (&free_pages);
}
list_init (&free_pages);
}
+/* Obtains and returns a free page. If PAL_ZERO is set in FLAGS,
+ then the page is filled with zeros. If no pages are
+ available, returns a null pointer, unless PAL_ASSERT is set in
+ FLAGS, in which case the kernel panics. */
void *
palloc_get (enum palloc_flags flags)
{
void *
palloc_get (enum palloc_flags flags)
{
@@
-65,6
+69,10
@@
palloc_get (enum palloc_flags flags)
lock_acquire (&lock);
lock_acquire (&lock);
+ /* If there's a page in the free list, take it.
+ Otherwise, if there's a page not yet added to the free list,
+ use it.
+ Otherwise, we're out of memory. */
if (!list_empty (&free_pages))
page = list_entry (list_pop_front (&free_pages), struct page, free_elem);
else if (uninit_start < uninit_end)
if (!list_empty (&free_pages))
page = list_entry (list_pop_front (&free_pages), struct page, free_elem);
else if (uninit_start < uninit_end)
@@
-91,6
+99,7
@@
palloc_get (enum palloc_flags flags)
return page;
}
return page;
}
+/* Frees PAGE. */
void
palloc_free (void *page_)
{
void
palloc_free (void *page_)
{