From: Arjan van de Ven <arjan@linux.intel.com>

Add a WARN() macro that acts like WARN_ON(), with the added feature that it
takes a printk like argument that is printed as part of the warning message.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/asm-generic/bug.h |   16 ++++++++++++++++
 kernel/panic.c            |   24 ++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff -puN include/asm-generic/bug.h~add-a-warn-macro-this-is-warn_on-printk-arguments include/asm-generic/bug.h
--- a/include/asm-generic/bug.h~add-a-warn-macro-this-is-warn_on-printk-arguments
+++ a/include/asm-generic/bug.h
@@ -34,9 +34,13 @@ struct bug_entry {
 #ifndef __WARN
 #ifndef __ASSEMBLY__
 extern void warn_on_slowpath(const char *file, const int line);
+extern void warn_slowpath(const char *file, const int line, const char *fmt, ...);
 #define WANT_WARN_ON_SLOWPATH
 #endif
 #define __WARN() warn_on_slowpath(__FILE__, __LINE__)
+#define __WARN_printf(arg...) warn_slowpath(__FILE__, __LINE__, arg)
+#else
+#define __WARN_printf(arg...) __WARN()
 #endif
 
 #ifndef WARN_ON
@@ -48,6 +52,18 @@ extern void warn_on_slowpath(const char 
 })
 #endif
 
+#ifndef WARN
+#define WARN(condition, format...) ({						\
+	int __ret_warn_on = !!(condition);				\
+	if (unlikely(__ret_warn_on))					\
+		__WARN_printf(format);					\
+	unlikely(__ret_warn_on);					\
+})
+#endif
+
+
+
+
 #else /* !CONFIG_BUG */
 #ifndef HAVE_ARCH_BUG
 #define BUG()
diff -puN kernel/panic.c~add-a-warn-macro-this-is-warn_on-printk-arguments kernel/panic.c
--- a/kernel/panic.c~add-a-warn-macro-this-is-warn_on-printk-arguments
+++ a/kernel/panic.c
@@ -321,6 +321,30 @@ void warn_on_slowpath(const char *file, 
 	add_taint(TAINT_WARN);
 }
 EXPORT_SYMBOL(warn_on_slowpath);
+
+
+void warn_slowpath(const char *file, int line, const char *fmt, ...)
+{
+	va_list args;
+
+
+	char function[KSYM_SYMBOL_LEN];
+	unsigned long caller = (unsigned long) __builtin_return_address(0);
+	sprint_symbol(function, caller);
+
+	printk(KERN_WARNING "------------[ cut here ]------------\n");
+	printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
+		line, function);
+	va_start(args, fmt);
+	vprintk(fmt, args);
+	va_end(args);
+
+	print_modules();
+	dump_stack();
+	print_oops_end_marker();
+	add_taint(TAINT_WARN);
+}
+EXPORT_SYMBOL(warn_slowpath);
 #endif
 
 #ifdef CONFIG_CC_STACKPROTECTOR
_