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kernel debug: support resetting WARN*_ONCE

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I like _ONCE warnings because it's guaranteed that they don't flood the
log.

During testing I find it useful to reset the state of the once warnings,
so that I can rerun tests and see if they trigger again, or can
guarantee that a test run always hits the same warnings.

This patch adds a debugfs interface to reset all the _ONCE warnings so
that they appear again:

  echo 1 > /sys/kernel/debug/clear_warn_once

This is implemented by putting all the warning booleans into a special
section, and clearing it.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20171017221455.6740-1-andi@firstfloor.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andi Kleen
2017-11-17 15:27:03 -08:00
committed by Linus Torvalds
parent fb6cc4ac15
commit b1fca27d38
5 changed files with 42 additions and 3 deletions
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6
include/asm-generic/bug.h
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@@ -130,7 +130,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
#ifndef WARN_ON_ONCE
#define WARN_ON_ONCE(condition) ({ \
static bool __section(.data.unlikely) __warned; \
static bool __section(.data.once) __warned; \
int __ret_warn_once = !!(condition); \
\
if (unlikely(__ret_warn_once && !__warned)) { \
@@ -142,7 +142,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
#endif
#define WARN_ONCE(condition, format...) ({ \
static bool __section(.data.unlikely) __warned; \
static bool __section(.data.once) __warned; \
int __ret_warn_once = !!(condition); \
\
if (unlikely(__ret_warn_once && !__warned)) { \
@@ -153,7 +153,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
})
#define WARN_TAINT_ONCE(condition, taint, format...) ({ \
static bool __section(.data.unlikely) __warned; \
static bool __section(.data.once) __warned; \
int __ret_warn_once = !!(condition); \
\
if (unlikely(__ret_warn_once && !__warned)) { \