Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

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

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

include/linux/string.h

+7 −0
Original line number Diff line number Diff line
@@ -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

lib/Kconfig.debug

+8 −0
Original line number Diff line number Diff line
@@ -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

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

lib/string.c

+31 −0
Original line number Diff line number Diff line
@@ -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

lib/test_memcat_p.c

0 → 100644
+115 −0
Original line number Diff line number Diff line 
// 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");