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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 /Documentation
parentfb6cc4ac15c354fa1eb449f50a0dfe5f4bf0d42a (diff)
downloadlinux-b1fca27d384e8418aac84b39f6f5179aecc1b64f.tar.bz2
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 'Documentation')
-rw-r--r--Documentation/clearing-warn-once.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/clearing-warn-once.txt b/Documentation/clearing-warn-once.txt
new file mode 100644
index 000000000000..5b1f5d547be1
--- /dev/null
+++ b/Documentation/clearing-warn-once.txt
@@ -0,0 +1,7 @@
+
+WARN_ONCE / WARN_ON_ONCE only print a warning once.
+
+echo 1 > /sys/kernel/debug/clear_warn_once
+
+clears the state and allows the warnings to print once again.
+This can be useful after test suite runs to reproduce problems.