[PATCH 1/4] lib min_heap: Improve type safety in min_heap macros by using container_of

Kuan-Wei Chiu
2024-11-29T18:12:34Z

The current implementation of min_heap macros uses explicit casting to
min_heap_char *, which prevents the compiler from detecting incorrect
pointer types. This can lead to errors if non-min_heap pointers are
passed inadvertently.

To enhance safety, replace all explicit casts to min_heap_char * with
the use of container_of(&(_heap)->nr, min_heap_char, nr). This approach
ensures that the _heap parameter is indeed a min_heap_char-compatible
structure, allowing the compiler to catch improper usages.

Link: https://lore.kernel.org/lkml/CAMuHMdVO5DPuD9HYWBFqKDHphx7+0BEhreUxtVC40A=8p6VAhQ@mail.gmail.com
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
include/linux/min_heap.h | 61 +++++++++++++++++++++++-----------------
1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h
index e781727c8916..456cfbc1b8f5 100644
--- a/include/linux/min_heap.h
+++ b/include/linux/min_heap.h
@@ -218,7 +218,7 @@ void __min_heap_init_inline(min_heap_char *heap, void *data, int size)
}

#define min_heap_init_inline(_heap, _data, _size) \
- __min_heap_init_inline((min_heap_char *)_heap, _data, _size)
+ __min_heap_init_inline(container_of(&(_heap)->nr, min_heap_char, nr), _data, _size)

/* Get the minimum element from the heap. */
static __always_inline
@@ -228,7 +228,8 @@ void *__min_heap_peek_inline(struct min_heap_char *heap)
}

#define min_heap_peek_inline(_heap) \
- (__minheap_cast(_heap) __min_heap_peek_inline((min_heap_char *)_heap))
+ (__minheap_cast(_heap) \
+ __min_heap_peek_inline(container_of(&(_heap)->nr, min_heap_char, nr)))

/* Check if the heap is full. */
static __always_inline
@@ -238,7 +239,7 @@ bool __min_heap_full_inline(min_heap_char *heap)
}

#define min_heap_full_inline(_heap) \
- __min_heap_full_inline((min_heap_char *)_heap)
+ __min_heap_full_inline(container_of(&(_heap)->nr, min_heap_char, nr))

/* Sift the element at pos down the heap. */
static __always_inline
@@ -277,8 +278,8 @@ void __min_heap_sift_down_inline(min_heap_char *heap, int pos, size_t elem_size,
}

#define min_heap_sift_down_inline(_heap, _pos, _func, _args) \
- __min_heap_sift_down_inline((min_heap_char *)_heap, _pos, __minheap_obj_size(_heap), \
- _func, _args)
+ __min_heap_sift_down_inline(container_of(&(_heap)->nr, min_heap_char, nr), _pos, \
+ __minheap_obj_size(_heap), _func, _args)

/* Sift up ith element from the heap, O(log2(nr)). */
static __always_inline
@@ -304,8 +305,8 @@ void __min_heap_sift_up_inline(min_heap_char *heap, size_t elem_size, size_t idx
}

#define min_heap_sift_up_inline(_heap, _idx, _func, _args) \
- __min_heap_sift_up_inline((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, \
- _func, _args)
+ __min_heap_sift_up_inline(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _idx, _func, _args)

/* Floyd's approach to heapification that is O(nr). */
static __always_inline
@@ -319,7 +320,8 @@ void __min_heapify_all_inline(min_heap_char *heap, size_t elem_size,
}

#define min_heapify_all_inline(_heap, _func, _args) \
- __min_heapify_all_inline((min_heap_char *)_heap, __minheap_obj_size(_heap), _func, _args)
+ __min_heapify_all_inline(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _func, _args)

/* Remove minimum element from the heap, O(log2(nr)). */
static __always_inline
@@ -340,7 +342,8 @@ bool __min_heap_pop_inline(min_heap_char *heap, size_t elem_size,
}

#define min_heap_pop_inline(_heap, _func, _args) \
- __min_heap_pop_inline((min_heap_char *)_heap, __minheap_obj_size(_heap), _func, _args)
+ __min_heap_pop_inline(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _func, _args)

/*
* Remove the minimum element and then push the given element. The
@@ -356,8 +359,8 @@ void __min_heap_pop_push_inline(min_heap_char *heap, const void *element, size_t
}

#define min_heap_pop_push_inline(_heap, _element, _func, _args) \
- __min_heap_pop_push_inline((min_heap_char *)_heap, _element, __minheap_obj_size(_heap), \
- _func, _args)
+ __min_heap_pop_push_inline(container_of(&(_heap)->nr, min_heap_char, nr), _element, \
+ __minheap_obj_size(_heap), _func, _args)

/* Push an element on to the heap, O(log2(nr)). */
static __always_inline
@@ -382,8 +385,8 @@ bool __min_heap_push_inline(min_heap_char *heap, const void *element, size_t ele
}

#define min_heap_push_inline(_heap, _element, _func, _args) \
- __min_heap_push_inline((min_heap_char *)_heap, _element, __minheap_obj_size(_heap), \
- _func, _args)
+ __min_heap_push_inline(container_of(&(_heap)->nr, min_heap_char, nr), _element, \
+ __minheap_obj_size(_heap), _func, _args)

/* Remove ith element from the heap, O(log2(nr)). */
static __always_inline
@@ -411,8 +414,8 @@ bool __min_heap_del_inline(min_heap_char *heap, size_t elem_size, size_t idx,
}

#define min_heap_del_inline(_heap, _idx, _func, _args) \
- __min_heap_del_inline((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, \
- _func, _args)
+ __min_heap_del_inline(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _idx, _func, _args)

void __min_heap_init(min_heap_char *heap, void *data, int size);
void *__min_heap_peek(struct min_heap_char *heap);
@@ -433,25 +436,31 @@ bool __min_heap_del(min_heap_char *heap, size_t elem_size, size_t idx,
const struct min_heap_callbacks *func, void *args);

#define min_heap_init(_heap, _data, _size) \
- __min_heap_init((min_heap_char *)_heap, _data, _size)
+ __min_heap_init(container_of(&(_heap)->nr, min_heap_char, nr), _data, _size)
#define min_heap_peek(_heap) \
- (__minheap_cast(_heap) __min_heap_peek((min_heap_char *)_heap))
+ (__minheap_cast(_heap) __min_heap_peek(container_of(&(_heap)->nr, min_heap_char, nr)))
#define min_heap_full(_heap) \
- __min_heap_full((min_heap_char *)_heap)
+ __min_heap_full(container_of(&(_heap)->nr, min_heap_char, nr))
#define min_heap_sift_down(_heap, _pos, _func, _args) \
- __min_heap_sift_down((min_heap_char *)_heap, _pos, __minheap_obj_size(_heap), _func, _args)
+ __min_heap_sift_down(container_of(&(_heap)->nr, min_heap_char, nr), _pos, \
+ __minheap_obj_size(_heap), _func, _args)
#define min_heap_sift_up(_heap, _idx, _func, _args) \
- __min_heap_sift_up((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, _func, _args)
+ __min_heap_sift_up(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _idx, _func, _args)
#define min_heapify_all(_heap, _func, _args) \
- __min_heapify_all((min_heap_char *)_heap, __minheap_obj_size(_heap), _func, _args)
+ __min_heapify_all(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _func, _args)
#define min_heap_pop(_heap, _func, _args) \
- __min_heap_pop((min_heap_char *)_heap, __minheap_obj_size(_heap), _func, _args)
+ __min_heap_pop(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _func, _args)
#define min_heap_pop_push(_heap, _element, _func, _args) \
- __min_heap_pop_push((min_heap_char *)_heap, _element, __minheap_obj_size(_heap), \
- _func, _args)
+ __min_heap_pop_push(container_of(&(_heap)->nr, min_heap_char, nr), _element, \
+ __minheap_obj_size(_heap), _func, _args)
#define min_heap_push(_heap, _element, _func, _args) \
- __min_heap_push((min_heap_char *)_heap, _element, __minheap_obj_size(_heap), _func, _args)
+ __min_heap_push(container_of(&(_heap)->nr, min_heap_char, nr), _element, \
+ __minheap_obj_size(_heap), _func, _args)
#define min_heap_del(_heap, _idx, _func, _args) \
- __min_heap_del((min_heap_char *)_heap, __minheap_obj_size(_heap), _idx, _func, _args)
+ __min_heap_del(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _idx, _func, _args)

#endif /* _LINUX_MIN_HEAP_H */
--
2.34.1