kstrto*: converting strings to integers done (hopefully) right

1. simple_strto*() do not contain overflow checks and crufty,
   libc way to indicate failure.
2. strict_strto*() also do not have overflow checks but the name and
   comments pretend they do.
3. Both families have only "long long" and "long" variants,
   but users want strtou8()
4. Both "simple" and "strict" prefixes are wrong:
   Simple doesn't exactly say what's so simple, strict should not exist
   because conversion should be strict by default.

The solution is to use "k" prefix and add convertors for more types.
Enter
	kstrtoull()
	kstrtoll()
	kstrtoul()
	kstrtol()
	kstrtouint()
	kstrtoint()

	kstrtou64()
	kstrtos64()
	kstrtou32()
	kstrtos32()
	kstrtou16()
	kstrtos16()
	kstrtou8()
	kstrtos8()

Include runtime testsuite (somewhat incomplete) as well.

strict_strto*() become deprecated, stubbed to kstrto*() and
eventually will be removed altogether.

Use kstrto*() in code today!

Note: on some archs _kstrtoul() and _kstrtol() are left in tree, even if
      they'll be unused at runtime. This is temporarily solution,
      because I don't want to hardcode list of archs where these
      functions aren't needed. Current solution with sizeof() and
      __alignof__ at least always works.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 1039 insertions, 150 deletions

diff --git a/drivers/video/via/viafbdev.h b/drivers/video/via/viafbdev.h
index d66f963e930e..137996dc547e 100644
--- a/drivers/video/via/viafbdev.h
+++ b/drivers/video/via/viafbdev.h
@@ -94,9 +94,6 @@ extern int viafb_LCD_ON;
 extern int viafb_DVI_ON;
 extern int viafb_hotplug;
 
-extern int strict_strtoul(const char *cp, unsigned int base,
-        unsigned long *res);
-
 u8 viafb_gpio_i2c_read_lvds(struct lvds_setting_information
         *plvds_setting_info, struct lvds_chip_information
         *plvds_chip_info, u8 index);
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2fe6e84894a4..00cec4dc0ae2 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -187,14 +187,76 @@ NORET_TYPE void do_exit(long error_code)
         ATTRIB_NORET;
 NORET_TYPE void complete_and_exit(struct completion *, long)
         ATTRIB_NORET;
+
+/* Internal, do not use. */
+int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
+int __must_check _kstrtol(const char *s, unsigned int base, long *res);
+
+int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
+int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
+static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
+{
+        /*
+         * We want to shortcut function call, but
+         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
+         */
+        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
+            __alignof__(unsigned long) == __alignof__(unsigned long long))
+                return kstrtoull(s, base, (unsigned long long *)res);
+        else
+                return _kstrtoul(s, base, res);
+}
+
+static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
+{
+        /*
+         * We want to shortcut function call, but
+         * __builtin_types_compatible_p(long, long long) = 0.
+         */
+        if (sizeof(long) == sizeof(long long) &&
+            __alignof__(long) == __alignof__(long long))
+                return kstrtoll(s, base, (long long *)res);
+        else
+                return _kstrtol(s, base, res);
+}
+
+int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
+int __must_check kstrtoint(const char *s, unsigned int base, int *res);
+
+static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
+{
+        return kstrtoull(s, base, res);
+}
+
+static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
+{
+        return kstrtoll(s, base, res);
+}
+
+static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
+{
+        return kstrtouint(s, base, res);
+}
+
+static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
+{
+        return kstrtoint(s, base, res);
+}
+
+int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
+int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
+int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
+int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
+
 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 extern long simple_strtol(const char *,char **,unsigned int);
 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 extern long long simple_strtoll(const char *,char **,unsigned int);
-extern int __must_check strict_strtoul(const char *, unsigned int, unsigned long *);
-extern int __must_check strict_strtol(const char *, unsigned int, long *);
-extern int __must_check strict_strtoull(const char *, unsigned int, unsigned long long *);
-extern int __must_check strict_strtoll(const char *, unsigned int, long long *);
+#define strict_strtoul  kstrtoul
+#define strict_strtol   kstrtol
+#define strict_strtoull kstrtoull
+#define strict_strtoll  kstrtoll
+
 extern int sprintf(char * buf, const char * fmt, ...)
         __attribute__ ((format (printf, 2, 3)));
 extern int vsprintf(char *buf, const char *, va_list)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index bef5faab660f..df9234c5f9d1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1250,3 +1250,6 @@ source "samples/Kconfig"
 source "lib/Kconfig.kgdb"
 
 source "lib/Kconfig.kmemcheck"
+
+config TEST_KSTRTOX
+        tristate "Test kstrto*() family of functions at runtime"
diff --git a/lib/Makefile b/lib/Makefile
index ef7ed71a6ffd..8c9de027ebb1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -22,6 +22,8 @@ lib-y	+= kobject.o kref.o klist.o
 obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
          bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
          string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o
+obj-y += kstrtox.o
+obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
 
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG
diff --git a/lib/kstrtox.c b/lib/kstrtox.c
new file mode 100644
index 000000000000..05672e819f8c
--- /dev/null
+++ b/lib/kstrtox.c
@@ -0,0 +1,227 @@
+/*
+ * Convert integer string representation to an integer.
+ * If an integer doesn't fit into specified type, -E is returned.
+ *
+ * Integer starts with optional sign.
+ * kstrtou*() functions do not accept sign "-".
+ *
+ * Radix 0 means autodetection: leading "0x" implies radix 16,
+ * leading "0" implies radix 8, otherwise radix is 10.
+ * Autodetection hints work after optional sign, but not before.
+ *
+ * If -E is returned, result is not touched.
+ */
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+static inline char _tolower(const char c)
+{
+        return c | 0x20;
+}
+
+static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
+{
+        unsigned long long acc;
+        int ok;
+
+        if (base == 0) {
+                if (s[0] == '0') {
+                        if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
+                                base = 16;
+                        else
+                                base = 8;
+                } else
+                        base = 10;
+        }
+        if (base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
+                s += 2;
+
+        acc = 0;
+        ok = 0;
+        while (*s) {
+                unsigned int val;
+
+                if ('0' <= *s && *s <= '9')
+                        val = *s - '0';
+                else if ('a' <= _tolower(*s) && _tolower(*s) <= 'f')
+                        val = _tolower(*s) - 'a' + 10;
+                else if (*s == '\n') {
+                        if (*(s + 1) == '\0')
+                                break;
+                        else
+                                return -EINVAL;
+                } else
+                        return -EINVAL;
+
+                if (val >= base)