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SubjectRe: [PATCH] Eliminate thousands of warnings in WARN_ON with gcc 3.2 build
On Thu, Apr 23, 2009 at 02:02:19PM +0200, Johannes Weiner wrote:
> > +{
> > + warn_slowpath_fmt(file, line, "");
> > +}
> > +EXPORT_SYMBOL(warn_slowpath_null);
>
> That should still emit a warning due to passing in a zero-length
> format string. Using (const char *){ 0 } as the literal would
> suppress it (on gcc 4.3.3 at least) but I'm not sure if it's worth the
> uglyness...

Hmm, you're right 3.3 generates a warning for that, 3.2 doesn't
But at least it's only a single one, not thousands.
Your trick would make sense. Updated patch attached.

-Andi

---

Eliminate thousands of warnings with gcc 3.2 build v2

When building with gcc 3.2 I get thousands of warnings about passing
a NULL format string to warn_on_slowpath(). Split this case out
into a separate call. This should also shrink the kernel
slightly.

v2: Avoid warning in warn_slowpath_null on newer gccs too (J.Weiner)

Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
include/asm-generic/bug.h | 7 ++++---
kernel/panic.c | 12 +++++++++---
2 files changed, 13 insertions(+), 6 deletions(-)

Index: linux-2.6.30-rc2-ak/include/asm-generic/bug.h
===================================================================
--- linux-2.6.30-rc2-ak.orig/include/asm-generic/bug.h 2009-01-11 20:20:40.000000000 +0100
+++ linux-2.6.30-rc2-ak/include/asm-generic/bug.h 2009-04-22 23:52:48.000000000 +0200
@@ -58,12 +58,13 @@
*/
#ifndef __WARN
#ifndef __ASSEMBLY__
-extern void warn_slowpath(const char *file, const int line,
+extern void warn_slowpath_fmt(const char *file, const int line,
const char *fmt, ...) __attribute__((format(printf, 3, 4)));
+extern void warn_slowpath_null(const char *file, const int line);
#define WANT_WARN_ON_SLOWPATH
#endif
-#define __WARN() warn_slowpath(__FILE__, __LINE__, NULL)
-#define __WARN_printf(arg...) warn_slowpath(__FILE__, __LINE__, arg)
+#define __WARN() warn_slowpath_null(__FILE__, __LINE__)
+#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg)
#else
#define __WARN_printf(arg...) do { printk(arg); __WARN(); } while (0)
#endif
Index: linux-2.6.30-rc2-ak/kernel/panic.c
===================================================================
--- linux-2.6.30-rc2-ak.orig/kernel/panic.c 2009-04-19 19:29:07.000000000 +0200
+++ linux-2.6.30-rc2-ak/kernel/panic.c 2009-04-23 14:17:34.000000000 +0200
@@ -342,7 +342,7 @@
}

#ifdef WANT_WARN_ON_SLOWPATH
-void warn_slowpath(const char *file, int line, const char *fmt, ...)
+void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
{
va_list args;
char function[KSYM_SYMBOL_LEN];
@@ -358,7 +358,7 @@
if (board)
printk(KERN_WARNING "Hardware name: %s\n", board);

- if (fmt) {
+ if (*fmt) {
va_start(args, fmt);
vprintk(fmt, args);
va_end(args);
@@ -369,7 +369,13 @@
print_oops_end_marker();
add_taint(TAINT_WARN);
}
-EXPORT_SYMBOL(warn_slowpath);
+EXPORT_SYMBOL(warn_slowpath_fmt);
+
+void warn_slowpath_null(const char *file, int line)
+{
+ warn_slowpath_fmt(file, line, (const char *) { 0 });
+}
+EXPORT_SYMBOL(warn_slowpath_null);
#endif

#ifdef CONFIG_CC_STACKPROTECTOR

--
ak@linux.intel.com -- Speaking for myself only.


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