Commit ce76d938 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Greg Kroah-Hartman

lib: Add memcat_p(): paste 2 pointer arrays together

This adds a helper to paste 2 pointer arrays together, useful for merging
various types of attribute arrays. There are a few places in the kernel
tree where this is open coded, and I just added one more in the STM class.

The naming is inspired by memset_p() and memcat(), and partial credit for
it goes to Andy Shevchenko.

This patch adds the function wrapped in a type-enforcing macro and a test
module.
Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6c7e4b68
......@@ -131,6 +131,13 @@ static inline void *memset_p(void **p, void *v, __kernel_size_t n)
return memset64((uint64_t *)p, (uintptr_t)v, n);
}
extern void **__memcat_p(void **a, void **b);
#define memcat_p(a, b) ({ \
BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)), \
"type mismatch in memcat_p()"); \
(typeof(*a) *)__memcat_p((void **)(a), (void **)(b)); \
})
#ifndef __HAVE_ARCH_MEMCPY
extern void * memcpy(void *,const void *,__kernel_size_t);
#endif
......
......@@ -1965,6 +1965,14 @@ config TEST_DEBUG_VIRTUAL
If unsure, say N.
config TEST_MEMCAT_P
tristate "Test memcat_p() helper function"
help
Test the memcat_p() helper for correctly merging two
pointer arrays together.
If unsure, say N.
endif # RUNTIME_TESTING_MENU
config MEMTEST
......
......@@ -71,6 +71,7 @@ obj-$(CONFIG_TEST_UUID) += test_uuid.o
obj-$(CONFIG_TEST_PARMAN) += test_parman.o
obj-$(CONFIG_TEST_KMOD) += test_kmod.o
obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o
ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG
......
......@@ -27,6 +27,7 @@
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <asm/byteorder.h>
#include <asm/word-at-a-time.h>
......@@ -890,6 +891,36 @@ void *memscan(void *addr, int c, size_t size)
EXPORT_SYMBOL(memscan);
#endif
/*
* Merge two NULL-terminated pointer arrays into a newly allocated
* array, which is also NULL-terminated. Nomenclature is inspired by
* memset_p() and memcat() found elsewhere in the kernel source tree.
*/
void **__memcat_p(void **a, void **b)
{
void **p = a, **new;
int nr;
/* count the elements in both arrays */
for (nr = 0, p = a; *p; nr++, p++)
;
for (p = b; *p; nr++, p++)
;
/* one for the NULL-terminator */
nr++;
new = kmalloc_array(nr, sizeof(void *), GFP_KERNEL);
if (!new)
return NULL;
/* nr -> last index; p points to NULL in b[] */
for (nr--; nr >= 0; nr--, p = p == b ? &a[nr] : p - 1)
new[nr] = *p;
return new;
}
EXPORT_SYMBOL_GPL(__memcat_p);
#ifndef __HAVE_ARCH_STRSTR
/**
* strstr - Find the first substring in a %NUL terminated string
......
// SPDX-License-Identifier: GPL-2.0
/*
* Test cases for memcat_p() in lib/string.c
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/module.h>
struct test_struct {
int num;
unsigned int magic;
};
#define MAGIC 0xf00ff00f
/* Size of each of the NULL-terminated input arrays */
#define INPUT_MAX 128
/* Expected number of non-NULL elements in the output array */
#define EXPECT (INPUT_MAX * 2 - 2)
static int __init test_memcat_p_init(void)
{
struct test_struct **in0, **in1, **out, **p;
int err = -ENOMEM, i, r, total = 0;
in0 = kcalloc(INPUT_MAX, sizeof(*in0), GFP_KERNEL);
if (!in0)
return err;
in1 = kcalloc(INPUT_MAX, sizeof(*in1), GFP_KERNEL);
if (!in1)
goto err_free_in0;
for (i = 0, r = 1; i < INPUT_MAX - 1; i++) {
in0[i] = kmalloc(sizeof(**in0), GFP_KERNEL);
if (!in0[i])
goto err_free_elements;
in1[i] = kmalloc(sizeof(**in1), GFP_KERNEL);
if (!in1[i]) {
kfree(in0[i]);
goto err_free_elements;
}
/* lifted from test_sort.c */
r = (r * 725861) % 6599;
in0[i]->num = r;
in1[i]->num = -r;
in0[i]->magic = MAGIC;
in1[i]->magic = MAGIC;
}
in0[i] = in1[i] = NULL;
out = memcat_p(in0, in1);
if (!out)
goto err_free_all_elements;
err = -EINVAL;
for (i = 0, p = out; *p && (i < INPUT_MAX * 2 - 1); p++, i++) {
total += (*p)->num;
if ((*p)->magic != MAGIC) {
pr_err("test failed: wrong magic at %d: %u\n", i,
(*p)->magic);
goto err_free_out;
}
}
if (total) {
pr_err("test failed: expected zero total, got %d\n", total);
goto err_free_out;
}
if (i != EXPECT) {
pr_err("test failed: expected output size %d, got %d\n",
EXPECT, i);
goto err_free_out;
}
for (i = 0; i < INPUT_MAX - 1; i++)
if (out[i] != in0[i] || out[i + INPUT_MAX - 1] != in1[i]) {
pr_err("test failed: wrong element order at %d\n", i);
goto err_free_out;
}
err = 0;
pr_info("test passed\n");
err_free_out:
kfree(out);
err_free_all_elements:
i = INPUT_MAX;
err_free_elements:
for (i--; i >= 0; i--) {
kfree(in1[i]);
kfree(in0[i]);
}
kfree(in1);
err_free_in0:
kfree(in0);
return err;
}
static void __exit test_memcat_p_exit(void)
{
}
module_init(test_memcat_p_init);
module_exit(test_memcat_p_exit);
MODULE_LICENSE("GPL");
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