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ccd0d44fad
The define to use ({0;}) for the !CONFIG_SMP case of WARN_ON_SMP()
can be confusing. As the WARN_ON_SMP() needs to be a nop when
CONFIG_SMP is not set, including all its parameters must not be
evaluated, and that it must work as both a stand alone statement
and inside an if condition, we define it to a funky ({0;}).
A simple "0" will not work as it causes gcc to give the warning that
the statement has no effect.
As this strange definition has raised a few eyebrows from some
major kernel developers, it is wise to document why we create such
a work of art.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
208 lines
5.5 KiB
C
208 lines
5.5 KiB
C
#ifndef _ASM_GENERIC_BUG_H
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#define _ASM_GENERIC_BUG_H
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#include <linux/compiler.h>
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#ifdef CONFIG_BUG
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#ifdef CONFIG_GENERIC_BUG
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#ifndef __ASSEMBLY__
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struct bug_entry {
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#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
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unsigned long bug_addr;
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#else
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signed int bug_addr_disp;
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#endif
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
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const char *file;
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#else
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signed int file_disp;
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#endif
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unsigned short line;
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#endif
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unsigned short flags;
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};
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#endif /* __ASSEMBLY__ */
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#define BUGFLAG_WARNING (1 << 0)
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#define BUGFLAG_TAINT(taint) (BUGFLAG_WARNING | ((taint) << 8))
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#define BUG_GET_TAINT(bug) ((bug)->flags >> 8)
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#endif /* CONFIG_GENERIC_BUG */
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/*
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* Don't use BUG() or BUG_ON() unless there's really no way out; one
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* example might be detecting data structure corruption in the middle
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* of an operation that can't be backed out of. If the (sub)system
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* can somehow continue operating, perhaps with reduced functionality,
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* it's probably not BUG-worthy.
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*
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* If you're tempted to BUG(), think again: is completely giving up
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* really the *only* solution? There are usually better options, where
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* users don't need to reboot ASAP and can mostly shut down cleanly.
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*/
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#ifndef HAVE_ARCH_BUG
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#define BUG() do { \
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printk("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
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panic("BUG!"); \
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} while (0)
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#endif
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#ifndef HAVE_ARCH_BUG_ON
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#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while(0)
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#endif
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/*
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* WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
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* significant issues that need prompt attention if they should ever
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* appear at runtime. Use the versions with printk format strings
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* to provide better diagnostics.
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*/
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#ifndef __WARN_TAINT
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#ifndef __ASSEMBLY__
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extern void warn_slowpath_fmt(const char *file, const int line,
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const char *fmt, ...) __attribute__((format(printf, 3, 4)));
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extern void warn_slowpath_fmt_taint(const char *file, const int line,
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unsigned taint, const char *fmt, ...)
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__attribute__((format(printf, 4, 5)));
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extern void warn_slowpath_null(const char *file, const int line);
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#define WANT_WARN_ON_SLOWPATH
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#endif
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#define __WARN() warn_slowpath_null(__FILE__, __LINE__)
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#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg)
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#define __WARN_printf_taint(taint, arg...) \
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warn_slowpath_fmt_taint(__FILE__, __LINE__, taint, arg)
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#else
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#define __WARN() __WARN_TAINT(TAINT_WARN)
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#define __WARN_printf(arg...) do { printk(arg); __WARN(); } while (0)
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#define __WARN_printf_taint(taint, arg...) \
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do { printk(arg); __WARN_TAINT(taint); } while (0)
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#endif
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#ifndef WARN_ON
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#define WARN_ON(condition) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN(); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#ifndef WARN
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#define WARN(condition, format...) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_printf(format); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#define WARN_TAINT(condition, taint, format...) ({ \
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int __ret_warn_on = !!(condition); \
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if (unlikely(__ret_warn_on)) \
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__WARN_printf_taint(taint, format); \
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unlikely(__ret_warn_on); \
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})
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#else /* !CONFIG_BUG */
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#ifndef HAVE_ARCH_BUG
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#define BUG() do {} while(0)
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#endif
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#ifndef HAVE_ARCH_BUG_ON
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#define BUG_ON(condition) do { if (condition) ; } while(0)
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#endif
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#ifndef HAVE_ARCH_WARN_ON
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#define WARN_ON(condition) ({ \
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int __ret_warn_on = !!(condition); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#ifndef WARN
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#define WARN(condition, format...) ({ \
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int __ret_warn_on = !!(condition); \
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unlikely(__ret_warn_on); \
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})
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#endif
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#define WARN_TAINT(condition, taint, format...) WARN_ON(condition)
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#endif
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#define WARN_ON_ONCE(condition) ({ \
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static bool __warned; \
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int __ret_warn_once = !!(condition); \
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\
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if (unlikely(__ret_warn_once)) \
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if (WARN_ON(!__warned)) \
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__warned = true; \
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unlikely(__ret_warn_once); \
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})
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#define WARN_ONCE(condition, format...) ({ \
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static bool __warned; \
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int __ret_warn_once = !!(condition); \
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\
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if (unlikely(__ret_warn_once)) \
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if (WARN(!__warned, format)) \
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__warned = true; \
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unlikely(__ret_warn_once); \
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})
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#define WARN_TAINT_ONCE(condition, taint, format...) ({ \
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static bool __warned; \
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int __ret_warn_once = !!(condition); \
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\
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if (unlikely(__ret_warn_once)) \
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if (WARN_TAINT(!__warned, taint, format)) \
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__warned = true; \
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unlikely(__ret_warn_once); \
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})
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#define WARN_ON_RATELIMIT(condition, state) \
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WARN_ON((condition) && __ratelimit(state))
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/*
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* WARN_ON_SMP() is for cases that the warning is either
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* meaningless for !SMP or may even cause failures.
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* This is usually used for cases that we have
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* WARN_ON(!spin_is_locked(&lock)) checks, as spin_is_locked()
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* returns 0 for uniprocessor settings.
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* It can also be used with values that are only defined
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* on SMP:
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*
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* struct foo {
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* [...]
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* #ifdef CONFIG_SMP
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* int bar;
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* #endif
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* };
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*
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* void func(struct foo *zoot)
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* {
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* WARN_ON_SMP(!zoot->bar);
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*
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* For CONFIG_SMP, WARN_ON_SMP() should act the same as WARN_ON(),
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* and should be a nop and return false for uniprocessor.
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*
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* if (WARN_ON_SMP(x)) returns true only when CONFIG_SMP is set
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* and x is true.
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*/
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#ifdef CONFIG_SMP
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# define WARN_ON_SMP(x) WARN_ON(x)
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#else
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/*
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* Use of ({0;}) because WARN_ON_SMP(x) may be used either as
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* a stand alone line statement or as a condition in an if ()
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* statement.
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* A simple "0" would cause gcc to give a "statement has no effect"
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* warning.
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*/
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# define WARN_ON_SMP(x) ({0;})
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#endif
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#endif
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