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Subject[PATCH] zsmalloc: use unsigned long instead of void *
Date
We should use unsigned long as handle instead of void * to avoid any
confusion. Without this, users may just treat zs_malloc return value as
a pointer and try to deference it.

This patch passed compile test(zram, zcache and ramster) and zram is
tested on qemu.

Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
Nitin, Konrad and I discussed and concluded that we should use 'unsigned long'
instead of 'void *'.
Look at the lengthy thread if you have a question.
http://marc.info/?l=linux-mm&m=133716653118566&w=4
Watch out! it has number of noises.

drivers/staging/zcache/zcache-main.c | 12 ++++++------
drivers/staging/zram/zram_drv.c | 16 ++++++++--------
drivers/staging/zram/zram_drv.h | 2 +-
drivers/staging/zsmalloc/zsmalloc-main.c | 24 ++++++++++++------------
drivers/staging/zsmalloc/zsmalloc.h | 8 ++++----
5 files changed, 31 insertions(+), 31 deletions(-)
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 2734dac..4c218a7 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -700,7 +700,7 @@ static struct zv_hdr *zv_create(struct zs_pool *pool, uint32_t pool_id,
struct zv_hdr *zv;
u32 size = clen + sizeof(struct zv_hdr);
int chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
- void *handle = NULL;
+ unsigned long handle = 0;

BUG_ON(!irqs_disabled());
BUG_ON(chunks >= NCHUNKS);
@@ -718,10 +718,10 @@ static struct zv_hdr *zv_create(struct zs_pool *pool, uint32_t pool_id,
memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
zs_unmap_object(pool, handle);
out:
- return handle;
+ return (struct zv_hdr *)handle;
}

-static void zv_free(struct zs_pool *pool, void *handle)
+static void zv_free(struct zs_pool *pool, unsigned long handle)
{
unsigned long flags;
struct zv_hdr *zv;
@@ -743,7 +743,7 @@ static void zv_free(struct zs_pool *pool, void *handle)
local_irq_restore(flags);
}

-static void zv_decompress(struct page *page, void *handle)
+static void zv_decompress(struct page *page, unsigned long handle)
{
unsigned int clen = PAGE_SIZE;
char *to_va;
@@ -1247,7 +1247,7 @@ static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw,
int ret = 0;

BUG_ON(is_ephemeral(pool));
- zv_decompress((struct page *)(data), pampd);
+ zv_decompress((struct page *)(data), (unsigned long)pampd);
return ret;
}

@@ -1282,7 +1282,7 @@ static void zcache_pampd_free(void *pampd, struct tmem_pool *pool,
atomic_dec(&zcache_curr_eph_pampd_count);
BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0);
} else {
- zv_free(cli->zspool, pampd);
+ zv_free(cli->zspool, (unsigned long)pampd);
atomic_dec(&zcache_curr_pers_pampd_count);
BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0);
}
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 685d612..abd69d1 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -135,7 +135,7 @@ static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)

static void zram_free_page(struct zram *zram, size_t index)
{
- void *handle = zram->table[index].handle;
+ unsigned long handle = zram->table[index].handle;

if (unlikely(!handle)) {
/*
@@ -150,7 +150,7 @@ static void zram_free_page(struct zram *zram, size_t index)
}

if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
- __free_page(handle);
+ __free_page((struct page *)handle);
zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED);
zram_stat_dec(&zram->stats.pages_expand);
goto out;
@@ -166,7 +166,7 @@ out:
zram->table[index].size);
zram_stat_dec(&zram->stats.pages_stored);

- zram->table[index].handle = NULL;
+ zram->table[index].handle = 0;
zram->table[index].size = 0;
}

@@ -189,7 +189,7 @@ static void handle_uncompressed_page(struct zram *zram, struct bio_vec *bvec,
unsigned char *user_mem, *cmem;

user_mem = kmap_atomic(page);
- cmem = kmap_atomic(zram->table[index].handle);
+ cmem = kmap_atomic((struct page *)zram->table[index].handle);

memcpy(user_mem + bvec->bv_offset, cmem + offset, bvec->bv_len);
kunmap_atomic(cmem);
@@ -317,7 +317,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
int ret;
u32 store_offset;
size_t clen;
- void *handle;
+ unsigned long handle;
struct zobj_header *zheader;
struct page *page, *page_store;
unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
@@ -399,7 +399,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
store_offset = 0;
zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
zram_stat_inc(&zram->stats.pages_expand);
- handle = page_store;
+ handle = (unsigned long)page_store;
src = kmap_atomic(page);
cmem = kmap_atomic(page_store);
goto memstore;
@@ -592,12 +592,12 @@ void __zram_reset_device(struct zram *zram)

/* Free all pages that are still in this zram device */
for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
- void *handle = zram->table[index].handle;
+ unsigned long handle = zram->table[index].handle;
if (!handle)
continue;

if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
- __free_page(handle);
+ __free_page((struct page *)handle);
else
zs_free(zram->mem_pool, handle);
}
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index fbe8ac9..7a7e256 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -81,7 +81,7 @@ enum zram_pageflags {

/* Allocated for each disk page */
struct table {
- void *handle;
+ unsigned long handle;
u16 size; /* object size (excluding header) */
u8 count; /* object ref count (not yet used) */
u8 flags;
diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
index 4496737..ae10a1a 100644
--- a/drivers/staging/zsmalloc/zsmalloc-main.c
+++ b/drivers/staging/zsmalloc/zsmalloc-main.c
@@ -247,10 +247,10 @@ static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
}

/* Decode <page, obj_idx> pair from the given object handle */
-static void obj_handle_to_location(void *handle, struct page **page,
+static void obj_handle_to_location(unsigned long handle, struct page **page,
unsigned long *obj_idx)
{
- unsigned long hval = (unsigned long)handle;
+ unsigned long hval = handle;

*page = pfn_to_page(hval >> OBJ_INDEX_BITS);
*obj_idx = hval & OBJ_INDEX_MASK;
@@ -568,12 +568,12 @@ EXPORT_SYMBOL_GPL(zs_destroy_pool);
* @size: size of block to allocate
*
* On success, handle to the allocated object is returned,
- * otherwise NULL.
+ * otherwise 0.
* Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
*/
-void *zs_malloc(struct zs_pool *pool, size_t size)
+unsigned long zs_malloc(struct zs_pool *pool, size_t size)
{
- void *obj;
+ unsigned long obj;
struct link_free *link;
int class_idx;
struct size_class *class;
@@ -582,7 +582,7 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
unsigned long m_objidx, m_offset;

if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
- return NULL;
+ return 0;

class_idx = get_size_class_index(size);
class = &pool->size_class[class_idx];
@@ -595,14 +595,14 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
spin_unlock(&class->lock);
first_page = alloc_zspage(class, pool->flags);
if (unlikely(!first_page))
- return NULL;
+ return 0;

set_zspage_mapping(first_page, class->index, ZS_EMPTY);
spin_lock(&class->lock);
class->pages_allocated += class->pages_per_zspage;
}

- obj = first_page->freelist;
+ obj = (unsigned long)first_page->freelist;
obj_handle_to_location(obj, &m_page, &m_objidx);
m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);

@@ -621,7 +621,7 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
}
EXPORT_SYMBOL_GPL(zs_malloc);

-void zs_free(struct zs_pool *pool, void *obj)
+void zs_free(struct zs_pool *pool, unsigned long obj)
{
struct link_free *link;
struct page *first_page, *f_page;
@@ -648,7 +648,7 @@ void zs_free(struct zs_pool *pool, void *obj)
+ f_offset);
link->next = first_page->freelist;
kunmap_atomic(link);
- first_page->freelist = obj;
+ first_page->freelist = (void *)obj;

first_page->inuse--;
fullness = fix_fullness_group(pool, first_page);
@@ -672,7 +672,7 @@ EXPORT_SYMBOL_GPL(zs_free);
* this function. When done with the object, it must be unmapped using
* zs_unmap_object
*/
-void *zs_map_object(struct zs_pool *pool, void *handle)
+void *zs_map_object(struct zs_pool *pool, unsigned long handle)
{
struct page *page;
unsigned long obj_idx, off;
@@ -712,7 +712,7 @@ void *zs_map_object(struct zs_pool *pool, void *handle)
}
EXPORT_SYMBOL_GPL(zs_map_object);

-void zs_unmap_object(struct zs_pool *pool, void *handle)
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
{
struct page *page;
unsigned long obj_idx, off;
diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/drivers/staging/zsmalloc/zsmalloc.h
index 949384e..485cbb1 100644
--- a/drivers/staging/zsmalloc/zsmalloc.h
+++ b/drivers/staging/zsmalloc/zsmalloc.h
@@ -20,11 +20,11 @@ struct zs_pool;
struct zs_pool *zs_create_pool(const char *name, gfp_t flags);
void zs_destroy_pool(struct zs_pool *pool);

-void *zs_malloc(struct zs_pool *pool, size_t size);
-void zs_free(struct zs_pool *pool, void *obj);
+unsigned long zs_malloc(struct zs_pool *pool, size_t size);
+void zs_free(struct zs_pool *pool, unsigned long obj);

-void *zs_map_object(struct zs_pool *pool, void *handle);
-void zs_unmap_object(struct zs_pool *pool, void *handle);
+void *zs_map_object(struct zs_pool *pool, unsigned long handle);
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle);

u64 zs_get_total_size_bytes(struct zs_pool *pool);

--
1.7.9.5


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