zsmalloc: zs_malloc: return ERR_PTR on failure

zs_malloc returns 0 if it fails.  zs_zpool_malloc will return -1 when
zs_malloc return 0.  But -1 makes the return value unclear.

For example, when zswap_frontswap_store calls zs_malloc through
zs_zpool_malloc, it will return -1 to its caller.  The other return value
is -EINVAL, -ENODEV or something else.

This commit changes zs_malloc to return ERR_PTR on failure.  It didn't
just let zs_zpool_malloc return -ENOMEM becaue zs_malloc has two types of
failure:

- size is not OK return -EINVAL
- memory alloc fail return -ENOMEM.

Link: https://lkml.kernel.org/r/20220714080757.12161-1-teawater@gmail.com
Signed-off-by: Hui Zhu <teawater@antgroup.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 3e281a1..9d3b06d 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1389,9 +1389,9 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
                        __GFP_HIGHMEM |
                        __GFP_MOVABLE);
 
-       if (unlikely(!handle)) {
+       if (IS_ERR((void *)handle)) {
                zcomp_stream_put(zram->comp);
-               return -ENOMEM;
+               return PTR_ERR((void *)handle);
        }
 
        alloced_pages = zs_get_total_pages(zram->mem_pool);

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index f24b715..9e13fd7 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -399,7 +399,10 @@ static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
                        unsigned long *handle)
 {
        *handle = zs_malloc(pool, size, gfp);
-       return *handle ? 0 : -1;
+
+       if (IS_ERR((void *)(*handle)))
+               return PTR_ERR((void *)*handle);
+       return 0;
 }
 static void zs_zpool_free(void *pool, unsigned long handle)
 {
@@ -1400,7 +1403,7 @@ static unsigned long obj_malloc(struct zs_pool *pool,
  * @gfp: gfp flags when allocating object
  *
  * On success, handle to the allocated object is returned,
- * otherwise 0.
+ * otherwise an ERR_PTR().
  * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
  */
 unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
@@ -1411,11 +1414,11 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
        struct zspage *zspage;
 
        if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
-               return 0;
+               return (unsigned long)ERR_PTR(-EINVAL);
 
        handle = cache_alloc_handle(pool, gfp);
        if (!handle)
-               return 0;
+               return (unsigned long)ERR_PTR(-ENOMEM);
 
        /* extra space in chunk to keep the handle */
        size += ZS_HANDLE_SIZE;
@@ -1440,7 +1443,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
        zspage = alloc_zspage(pool, class, gfp);
        if (!zspage) {
                cache_free_handle(pool, handle);
-               return 0;
+               return (unsigned long)ERR_PTR(-ENOMEM);
        }
 
        spin_lock(&class->lock);