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scst/include/backport.h: Add kmalloc_obj() helper family

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Add compatibility helpers for the kmalloc_obj() family so SCST can use
the typed allocation helpers on kernels that do not provide them yet.

A following patch will convert existing non-scalar allocations to use
these helpers.

This patch doesn't change any functionality.
This commit is contained in:
Gleb Chesnokov
2026-04-11 18:58:57 +03:00
parent 5d74814c36
commit 77c1efbc1e
1 changed files with 181 additions and 4 deletions
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185
scst/include/backport.h
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@@ -38,6 +38,13 @@
#include <linux/iocontext.h>
#include <linux/jiffies.h>
#include <linux/kobject_ns.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 18, 0)
#include <linux/overflow.h>
#endif
#if defined(RHEL_MAJOR) && RHEL_MAJOR -0 >= 7 || \
LINUX_VERSION_CODE >= KERNEL_VERSION(3, 11, 0)
#include <linux/percpu-refcount.h>
#endif
#include <linux/preempt.h>
#include <linux/scatterlist.h> /* struct scatterlist */
#include <linux/shrinker.h>
@@ -1137,13 +1144,123 @@ struct nvmefc_fcp_req {
} __aligned(sizeof(u64)); /* alignment for other things alloc'd with */
#endif
/* <linux/percpu-refcount.h> */
/* <linux/overflow.h> */
#if defined(RHEL_MAJOR) && RHEL_MAJOR -0 >= 7 || \
LINUX_VERSION_CODE >= KERNEL_VERSION(3, 11, 0)
#include <linux/percpu-refcount.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 18, 0)
/*
* See also commit f0907827a8a9 ("compiler.h: enable builtin overflow checkers
* and add fallback code") # v4.18.
*/
static __always_inline bool __must_check __must_check_overflow(bool overflow)
{
return unlikely(overflow);
}
#define check_mul_overflow(a, b, d) \
__must_check_overflow(__builtin_mul_overflow(a, b, d))
#define check_add_overflow(a, b, d) \
__must_check_overflow(__builtin_add_overflow(a, b, d))
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 18, 0) && \
(LINUX_VERSION_CODE >> 8 != KERNEL_VERSION(5, 15, 0) >> 8 || \
LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 86)) && \
(LINUX_VERSION_CODE >> 8 != KERNEL_VERSION(5, 10, 0) >> 8 || \
LINUX_VERSION_CODE < KERNEL_VERSION(5, 10, 201)) && \
(LINUX_VERSION_CODE >> 8 != KERNEL_VERSION(5, 4, 0) >> 8 || \
LINUX_VERSION_CODE < KERNEL_VERSION(5, 4, 283)) && \
(LINUX_VERSION_CODE >> 8 != KERNEL_VERSION(4, 19, 0) >> 8 || \
LINUX_VERSION_CODE < KERNEL_VERSION(4, 19, 321)) && \
(!defined(RHEL_MAJOR) || RHEL_MAJOR -0 < 8 || \
RHEL_MAJOR -0 == 8 && RHEL_MINOR -0 < 10 || \
RHEL_MAJOR -0 == 9 && RHEL_MINOR -0 < 3) && \
(!defined(UEK_KABI_RENAME) || \
LINUX_VERSION_CODE < KERNEL_VERSION(4, 14, 0))
/*
* See also commit e1be43d9b5d0 ("overflow: Implement size_t saturating
* arithmetic helpers") # v5.18.
* See also commit 30f20ceb87f7 # v5.15.86.
* See also commit 2b46db3bb73d # v5.10.201.
* See also commit 1ab137a90eea # v5.4.283.
* See also commit 1f5cbd781779 # v4.19.321.
*/
static __always_inline size_t __must_check size_mul(size_t factor1, size_t factor2)
{
size_t bytes;
if (check_mul_overflow(factor1, factor2, &bytes))
return SIZE_MAX;
return bytes;
}
static __always_inline size_t __must_check size_add(size_t addend1, size_t addend2)
{
size_t bytes;
if (check_add_overflow(addend1, addend2, &bytes))
return SIZE_MAX;
return bytes;
}
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 17, 0)
/*
* See also commit 3c8ba0d61d04 ("kernel.h: Retain constant expression output
* for max()/min()") # v4.17.
*/
#define __is_constexpr(x) \
(sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 18, 0)
/*
* See also commit 610b15c50e86 ("overflow.h: Add allocation size calculation
* helpers") # v4.18.
*/
#define flex_array_size(p, member, count) \
__builtin_choose_expr(__is_constexpr(count), \
(count) * sizeof(*(p)->member) + __must_be_array((p)->member), \
size_mul(count, sizeof(*(p)->member) + __must_be_array((p)->member)))
#define struct_size(p, member, count) \
__builtin_choose_expr(__is_constexpr(count), \
sizeof(*(p)) + flex_array_size(p, member, count), \
size_add(sizeof(*(p)), flex_array_size(p, member, count)))
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(6, 5, 0)
/*
* See also commit d67790ddf021 ("overflow: Add struct_size_t() helper") # v6.5.
*/
#define struct_size_t(type, member, count) \
struct_size((type *)NULL, member, count)
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(7, 0, 0)
/*
* See also commit 81cee9166a90 ("compiler_types: Introduce __flex_counter()
* and family") # v7.0.
*/
#if defined(__has_builtin) && __has_builtin(__builtin_counted_by_ref)
#define __flex_counter(FAM) __builtin_counted_by_ref(FAM)
#else
#define __flex_counter(FAM) ((void *)NULL)
#endif
#define __set_flex_counter(FAM, COUNT) \
({ \
*_Generic(__flex_counter(FAM), \
void *: &(size_t){ 0 }, \
default: __flex_counter(FAM)) = (COUNT); \
})
#endif
/* <linux/percpu-refcount.h> */
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 3, 0) && \
(!defined(RHEL_RELEASE_CODE) || \
RHEL_RELEASE_CODE -0 < RHEL_RELEASE_VERSION(8, 3))
@@ -1530,6 +1647,66 @@ static inline struct kmem_cache *kmem_cache_create_usercopy(const char *name,
sizeof_field(struct __struct, __field), NULL)
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(7, 0, 0)
/*
* See also commit e19e1b480ac7 ("add default_gfp() helper macro and use it
* in the new *alloc_obj() helpers") # v7.0.
*/
#define __default_gfp(a,...) a
#define default_gfp(...) __default_gfp(__VA_ARGS__ __VA_OPT__(,) GFP_KERNEL)
/*
* See also commit 2932ba8d9c99 ("slab: Introduce kmalloc_obj() and family") # v7.0.
* See also commit e4c8b46b924e ("slab: Introduce kmalloc_flex() and family") # v7.0.
*/
#define __alloc_objs(KMALLOC, GFP, TYPE, COUNT) \
({ \
const size_t __obj_size = size_mul(sizeof(TYPE), COUNT); \
(TYPE *)KMALLOC(__obj_size, GFP); \
})
#define __alloc_flex(KMALLOC, GFP, TYPE, FAM, COUNT) \
({ \
const size_t __count = (COUNT); \
const size_t __obj_size = struct_size_t(TYPE, FAM, __count); \
TYPE *__obj_ptr = KMALLOC(__obj_size, GFP); \
if (__obj_ptr) \
__set_flex_counter(__obj_ptr->FAM, __count); \
__obj_ptr; \
})
#define kmalloc_obj(VAR_OR_TYPE, ...) \
__alloc_objs(kmalloc, default_gfp(__VA_ARGS__), typeof(VAR_OR_TYPE), 1)
#define kmalloc_objs(VAR_OR_TYPE, COUNT, ...) \
__alloc_objs(kmalloc, default_gfp(__VA_ARGS__), typeof(VAR_OR_TYPE), COUNT)
#define kmalloc_flex(VAR_OR_TYPE, FAM, COUNT, ...) \
__alloc_flex(kmalloc, default_gfp(__VA_ARGS__), typeof(VAR_OR_TYPE), FAM, COUNT)
/* All kzalloc aliases for kmalloc_(obj|objs|flex). */
#define kzalloc_obj(P, ...) \
__alloc_objs(kzalloc, default_gfp(__VA_ARGS__), typeof(P), 1)
#define kzalloc_objs(P, COUNT, ...) \
__alloc_objs(kzalloc, default_gfp(__VA_ARGS__), typeof(P), COUNT)
#define kzalloc_flex(P, FAM, COUNT, ...) \
__alloc_flex(kzalloc, default_gfp(__VA_ARGS__), typeof(P), FAM, COUNT)
/* All kvmalloc aliases for kmalloc_(obj|objs|flex). */
#define kvmalloc_obj(P, ...) \
__alloc_objs(kvmalloc, default_gfp(__VA_ARGS__), typeof(P), 1)
#define kvmalloc_objs(P, COUNT, ...) \
__alloc_objs(kvmalloc, default_gfp(__VA_ARGS__), typeof(P), COUNT)
#define kvmalloc_flex(P, FAM, COUNT, ...) \
__alloc_flex(kvmalloc, default_gfp(__VA_ARGS__), typeof(P), FAM, COUNT)
/* All kvzalloc aliases for kmalloc_(obj|objs|flex). */
#define kvzalloc_obj(P, ...) \
__alloc_objs(kvzalloc, default_gfp(__VA_ARGS__), typeof(P), 1)
#define kvzalloc_objs(P, COUNT, ...) \
__alloc_objs(kvzalloc, default_gfp(__VA_ARGS__), typeof(P), COUNT)
#define kvzalloc_flex(P, FAM, COUNT, ...) \
__alloc_flex(kvzalloc, default_gfp(__VA_ARGS__), typeof(P), FAM, COUNT)
#endif
/* <linux/sockptr.h> */
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 9, 0)