slab: add struct kmem_cache_args

Currently we have multiple kmem_cache_create*() variants that take up to
seven separate parameters with one of the functions having to grow an
eigth parameter in the future to handle both usercopy and a custom
freelist pointer.

Add a struct kmem_cache_args structure and move less common parameters
into it. Core parameters such as name, object size, and flags continue
to be passed separately.

Add a new function __kmem_cache_create_args() that takes a struct
kmem_cache_args pointer and port do_kmem_cache_create_usercopy() over to
it.

In follow-up patches we will port the other kmem_cache_create*()
variants over to it as well.

Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 5b2da2cf31a8..2b8eeca7fd2c 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -240,6 +240,28 @@ struct mem_cgroup;
  */
 bool slab_is_available(void);
 
+/**
+ * struct kmem_cache_args - Less common arguments for kmem_cache_create()
+ * @align: The required alignment for the objects.
+ * @useroffset: Usercopy region offset
+ * @usersize: Usercopy region size
+ * @freeptr_offset: Custom offset for the free pointer in RCU caches
+ * @use_freeptr_offset: Whether a @freeptr_offset is used
+ * @ctor: A constructor for the objects.
+ */
+struct kmem_cache_args {
+	unsigned int align;
+	unsigned int useroffset;
+	unsigned int usersize;
+	unsigned int freeptr_offset;
+	bool use_freeptr_offset;
+	void (*ctor)(void *);
+};
+
+struct kmem_cache *__kmem_cache_create_args(const char *name,
+					    unsigned int object_size,
+					    struct kmem_cache_args *args,
+					    slab_flags_t flags);
 struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
 			unsigned int align, slab_flags_t flags,
 			void (*ctor)(void *));