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authorFreeman Wang <xwang@ubicom.com>2009-12-19 13:43:00 -0800
committerAustin Foxley <austinf@cetoncorp.com>2009-12-19 13:53:32 -0800
commit23528282b771d1af3df0fa17f1e909ad3b663f59 (patch)
treeb51c4b640cf7f22708e027739e322dc573a3d430 /libc/stdlib
parent7dcd83e8bded560b6a2c658889995390d3021a92 (diff)
malloc: fix race condition and other bugs in the no-mmu malloc
Fixes multiple race conditions on mmb list. This was done by making the mmb_heap_lock into a recursive lock and making the regular heap_lock extend to cover the mmb heap handling. Also move the new_mmb allocation up to before the mmb list is iterated through to find the insertion point. When the mmb_heap also runs out and needs to be extended when the regular heap is just extended, the mmb list could be messed up. Signed-off-by: Freeman Wang <xwang@ubicom.com> Signed-off-by: Austin Foxley <austinf@cetoncorp.com>
Diffstat (limited to 'libc/stdlib')
-rw-r--r--libc/stdlib/malloc/free.c6
-rw-r--r--libc/stdlib/malloc/malloc.c7
2 files changed, 7 insertions, 6 deletions
diff --git a/libc/stdlib/malloc/free.c b/libc/stdlib/malloc/free.c
index c17e7ec2a..e7b6a290a 100644
--- a/libc/stdlib/malloc/free.c
+++ b/libc/stdlib/malloc/free.c
@@ -177,14 +177,14 @@ __free_to_heap (void *mem, struct heap_free_area **heap
/* Start searching again from the end of this block. */
start = mmb_end;
+ /* Release the descriptor block we used. */
+ free_to_heap (mmb, &__malloc_mmb_heap, &__malloc_mmb_heap_lock);
+
/* We have to unlock the heap before we recurse to free the mmb
descriptor, because we might be unmapping from the mmb
heap. */
__heap_unlock (heap_lock);
- /* Release the descriptor block we used. */
- free_to_heap (mmb, &__malloc_mmb_heap, &__malloc_mmb_heap_lock);
-
/* Do the actual munmap. */
munmap ((void *)mmb_start, mmb_end - mmb_start);
diff --git a/libc/stdlib/malloc/malloc.c b/libc/stdlib/malloc/malloc.c
index 337206f09..d58a7d0ee 100644
--- a/libc/stdlib/malloc/malloc.c
+++ b/libc/stdlib/malloc/malloc.c
@@ -46,7 +46,7 @@ struct malloc_mmb *__malloc_mmapped_blocks = 0;
HEAP_DECLARE_STATIC_FREE_AREA (initial_mmb_fa, 48); /* enough for 3 mmbs */
struct heap_free_area *__malloc_mmb_heap = HEAP_INIT_WITH_FA (initial_mmb_fa);
#ifdef HEAP_USE_LOCKING
-malloc_mutex_t __malloc_mmb_heap_lock = PTHREAD_MUTEX_INITIALIZER;
+malloc_mutex_t __malloc_mmb_heap_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
#endif
#endif /* __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */
@@ -149,19 +149,19 @@ __malloc_from_heap (size_t size, struct heap_free_area **heap
/* Try again to allocate. */
mem = __heap_alloc (heap, &size);
- __heap_unlock (heap_lock);
#if !defined(MALLOC_USE_SBRK) && defined(__UCLIBC_UCLINUX_BROKEN_MUNMAP__)
/* Insert a record of BLOCK in sorted order into the
__malloc_mmapped_blocks list. */
+ new_mmb = malloc_from_heap (sizeof *new_mmb, &__malloc_mmb_heap, &__malloc_mmb_heap_lock);
+
for (prev_mmb = 0, mmb = __malloc_mmapped_blocks;
mmb;
prev_mmb = mmb, mmb = mmb->next)
if (block < mmb->mem)
break;
- new_mmb = malloc_from_heap (sizeof *new_mmb, &__malloc_mmb_heap, &__malloc_mmb_heap_lock);
new_mmb->next = mmb;
new_mmb->mem = block;
new_mmb->size = block_size;
@@ -175,6 +175,7 @@ __malloc_from_heap (size_t size, struct heap_free_area **heap
(unsigned)new_mmb,
(unsigned)new_mmb->mem, block_size);
#endif /* !MALLOC_USE_SBRK && __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */
+ __heap_unlock (heap_lock);
}
}