This is a note to let you know that I've just added the patch titled
docs: fault-injection: fix non-working usage of negative values
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
docs-fault-injection-fix-non-working-usage-of-negati.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9d8a8987c1a48dfe506b85b2c1db8527b3f399f4
Author: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Date: Thu Jun 3 14:58:41 2021 +0200
docs: fault-injection: fix non-working usage of negative values
[ Upstream commit 005747526d4f3c2ec995891e95cb7625161022f9 ]
Fault injection uses debugfs in a way that the provided values via sysfs
are interpreted as u64. Providing negative numbers results in an error:
/sys/kernel/debug/fail_function# echo -1 > times
sh: write error: Invalid argument
Update the docs and examples to use "printf %#x <val>" in these cases.
For "retval", reword the paragraph a little and fix a typo.
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210603125841.27436-1-wsa+renesas@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
Stable-dep-of: d472cf797c4e ("debugfs: fix error when writing negative value to atomic_t debugfs file")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/fault-injection/fault-injection.rst b/Documentation/fault-injection/fault-injection.rst
index f51bb21d20e4..e4056dc51e7f 100644
--- a/Documentation/fault-injection/fault-injection.rst
+++ b/Documentation/fault-injection/fault-injection.rst
@@ -74,8 +74,10 @@ configuration of fault-injection capabilities.
- /sys/kernel/debug/fail*/times:
- specifies how many times failures may happen at most.
- A value of -1 means "no limit".
+ specifies how many times failures may happen at most. A value of -1
+ means "no limit". Note, though, that this file only accepts unsigned
+ values. So, if you want to specify -1, you better use 'printf' instead
+ of 'echo', e.g.: $ printf %#x -1 > times
- /sys/kernel/debug/fail*/space:
@@ -163,11 +165,13 @@ configuration of fault-injection capabilities.
- ERRNO: retval must be -1 to -MAX_ERRNO (-4096).
- ERR_NULL: retval must be 0 or -1 to -MAX_ERRNO (-4096).
-- /sys/kernel/debug/fail_function/<functiuon-name>/retval:
+- /sys/kernel/debug/fail_function/<function-name>/retval:
- specifies the "error" return value to inject to the given
- function for given function. This will be created when
- user specifies new injection entry.
+ specifies the "error" return value to inject to the given function.
+ This will be created when the user specifies a new injection entry.
+ Note that this file only accepts unsigned values. So, if you want to
+ use a negative errno, you better use 'printf' instead of 'echo', e.g.:
+ $ printf %#x -12 > retval
Boot option
^^^^^^^^^^^
@@ -250,7 +254,7 @@ Application Examples
echo Y > /sys/kernel/debug/$FAILTYPE/task-filter
echo 10 > /sys/kernel/debug/$FAILTYPE/probability
echo 100 > /sys/kernel/debug/$FAILTYPE/interval
- echo -1 > /sys/kernel/debug/$FAILTYPE/times
+ printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times
echo 0 > /sys/kernel/debug/$FAILTYPE/space
echo 2 > /sys/kernel/debug/$FAILTYPE/verbose
echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@@ -304,7 +308,7 @@ Application Examples
echo N > /sys/kernel/debug/$FAILTYPE/task-filter
echo 10 > /sys/kernel/debug/$FAILTYPE/probability
echo 100 > /sys/kernel/debug/$FAILTYPE/interval
- echo -1 > /sys/kernel/debug/$FAILTYPE/times
+ printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times
echo 0 > /sys/kernel/debug/$FAILTYPE/space
echo 2 > /sys/kernel/debug/$FAILTYPE/verbose
echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@@ -331,11 +335,11 @@ Application Examples
FAILTYPE=fail_function
FAILFUNC=open_ctree
echo $FAILFUNC > /sys/kernel/debug/$FAILTYPE/inject
- echo -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval
+ printf %#x -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval
echo N > /sys/kernel/debug/$FAILTYPE/task-filter
echo 100 > /sys/kernel/debug/$FAILTYPE/probability
echo 0 > /sys/kernel/debug/$FAILTYPE/interval
- echo -1 > /sys/kernel/debug/$FAILTYPE/times
+ printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times
echo 0 > /sys/kernel/debug/$FAILTYPE/space
echo 1 > /sys/kernel/debug/$FAILTYPE/verbose
