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Message-ID: <20110520061259.GA13483@p183>
Date: Fri, 20 May 2011 09:15:55 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, arnd@...db.de, mmarek@...e.cz,
linux-kbuild@...r.kernel.org
Subject: [PATCH] kstrtox: drop kstrtol()/kstrtoul() when possible
If "long" and "long long" types are identical at runtime,
kstrtol() can be aliased to kstrtoll().
Unfortunately, one can't write
#if sizeof(long) == sizeof(long long) ...
To solve this, generate header file with sizes and alignment of
interesting types like we do with bounds.h and asm-offsets.h.
Everything above applies to "unsigned long" and kstrtoul().
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
Kbuild | 45 +++++++++++++++++++++++++++++++++++++++------
include/linux/kernel.h | 27 ++++++++-------------------
kernel/sizeof.c | 10 ++++++++++
lib/kstrtox.c | 19 +++++++++++++------
4 files changed, 70 insertions(+), 31 deletions(-)
--- a/Kbuild
+++ b/Kbuild
@@ -5,13 +5,16 @@
# 2) Generate asm-offsets.h (may need bounds.h)
# 3) Check for missing system calls
+always :=
+targets :=
+
#####
-# 1) Generate bounds.h
+# Generate bounds.h
bounds-file := include/generated/bounds.h
-always := $(bounds-file)
-targets := $(bounds-file) kernel/bounds.s
+always += $(bounds-file)
+targets += $(bounds-file) kernel/bounds.s
quiet_cmd_bounds = GEN $@
define cmd_bounds
@@ -39,8 +42,38 @@ $(obj)/$(bounds-file): kernel/bounds.s Kbuild
$(Q)mkdir -p $(dir $@)
$(call cmd,bounds)
+# generated/sizeof.h
+sizeof-file := include/generated/sizeof.h
+
+always += $(sizeof-file)
+targets += $(sizeof-file) kernel/sizeof.s
+
+quiet_cmd_sizeof = GEN $@
+define cmd_sizeof
+ ( \
+ set -e; \
+ echo "#ifndef _LINUX_SIZEOF_H"; \
+ echo "#define _LINUX_SIZEOF_H"; \
+ echo "/*"; \
+ echo " * This file is automatically generated from kernel/sizeof.c .";\
+ echo " * Modifying is futile."; \
+ echo " */"; \
+ sed -ne $(sed-y) $<; \
+ echo "#endif" \
+ ) >$@
+endef
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+kernel/sizeof.s: kernel/sizeof.c FORCE
+ $(Q)mkdir -p $(dir $@)
+ $(call if_changed_dep,cc_s_c)
+
+$(obj)/$(sizeof-file): kernel/sizeof.s Kbuild
+ $(Q)mkdir -p $(dir $@)
+ $(call cmd,sizeof)
+
#####
-# 2) Generate asm-offsets.h
+# Generate asm-offsets.h
#
offsets-file := include/generated/asm-offsets.h
@@ -85,7 +118,7 @@ $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
$(call cmd,offsets)
#####
-# 3) Check for missing system calls
+# Check for missing system calls
#
quiet_cmd_syscalls = CALL $<
@@ -96,4 +129,4 @@ missing-syscalls: scripts/checksyscalls.sh FORCE
$(call cmd,syscalls)
# Keep these two files during make clean
-no-clean-files := $(bounds-file) $(offsets-file)
+no-clean-files := $(bounds-file) $(offsets-file) $(sizeof-file)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -8,6 +8,7 @@
#define __ALIGN_KERNEL_MASK(x, mask) (((x) + (mask)) & ~(mask))
#ifdef __KERNEL__
+#include <generated/sizeof.h>
#include <stdarg.h>
#include <linux/linkage.h>
@@ -194,32 +195,20 @@ 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);
+#if SIZEOF_LONG == SIZEOF_LONG_LONG && ALIGNOF_LONG == ALIGNOF_LONG_LONG
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);
+ return kstrtoull(s, base, (unsigned long long *)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);
+ return kstrtoll(s, base, (long long *)res);
}
-
+#else
+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);
+#endif
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);
new file mode 100644
--- /dev/null
+++ b/kernel/sizeof.c
@@ -0,0 +1,10 @@
+#include <linux/kbuild.h>
+
+void f(void)
+{
+ DEFINE(SIZEOF_LONG, sizeof(long));
+ DEFINE(ALIGNOF_LONG, __alignof__(long));
+
+ DEFINE(SIZEOF_LONG_LONG, sizeof(long long));
+ DEFINE(ALIGNOF_LONG_LONG, __alignof__(long long));
+}
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -11,6 +11,7 @@
*
* If -E is returned, result is not touched.
*/
+#include <generated/sizeof.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/kernel.h>
@@ -101,8 +102,14 @@ int kstrtoll(const char *s, unsigned int base, long long *res)
}
EXPORT_SYMBOL(kstrtoll);
-/* Internal, do not use. */
-int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
+#if SIZEOF_LONG == SIZEOF_LONG_LONG && ALIGNOF_LONG == ALIGNOF_LONG_LONG
+/*
+ * Shortcut function call if types are indistinguishable at runtime.
+ * FYI, both __builtin_types_compatible_p(unsigned long, unsigned long long)
+ * and __builtin_types_compatible_p(long, long long) are always 0.
+ */
+#else
+int kstrtoul(const char *s, unsigned int base, unsigned long *res)
{
unsigned long long tmp;
int rv;
@@ -115,10 +122,9 @@ int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
*res = tmp;
return 0;
}
-EXPORT_SYMBOL(_kstrtoul);
+EXPORT_SYMBOL(kstrtoul);
-/* Internal, do not use. */
-int _kstrtol(const char *s, unsigned int base, long *res)
+int kstrtol(const char *s, unsigned int base, long *res)
{
long long tmp;
int rv;
@@ -131,7 +137,8 @@ int _kstrtol(const char *s, unsigned int base, long *res)
*res = tmp;
return 0;
}
-EXPORT_SYMBOL(_kstrtol);
+EXPORT_SYMBOL(kstrtol);
+#endif
int kstrtouint(const char *s, unsigned int base, unsigned int *res)
{
--
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