path: root/kernel
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authorAndi Kleen <ak@linux.intel.com>2017-11-17 15:27:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-17 16:10:00 -0800
commitb1fca27d384e8418aac84b39f6f5179aecc1b64f (patch)
treee08be97de59a1cbb16df46273aadef161358b8ba /kernel
parentfb6cc4ac15c354fa1eb449f50a0dfe5f4bf0d42a (diff)
kernel debug: support resetting WARN*_ONCE
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>
Diffstat (limited to 'kernel')
1 files changed, 28 insertions, 0 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index bdd18afa19a4..672a91dc20fe 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -27,6 +27,8 @@
#include <linux/console.h>
#include <linux/bug.h>
#include <linux/ratelimit.h>
+#include <linux/debugfs.h>
+#include <asm/sections.h>
#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18
@@ -587,6 +589,32 @@ void warn_slowpath_null(const char *file, int line)
+#ifdef CONFIG_BUG
+/* Support resetting WARN*_ONCE state */
+static int clear_warn_once_set(void *data, u64 val)
+ memset(__start_once, 0, __end_once - __start_once);
+ return 0;
+ clear_warn_once_set,
+ "%lld\n");
+static __init int register_warn_debugfs(void)
+ /* Don't care about failure */
+ debugfs_create_file("clear_warn_once", 0644, NULL,
+ NULL, &clear_warn_once_fops);
+ return 0;

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