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| author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2021-06-03 14:58:41 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2021-06-14 15:58:22 -0600 |
| commit | 005747526d4f3c2ec995891e95cb7625161022f9 (patch) | |
| tree | 012d3da858ae493cf64ccb040754a6bff528c9c8 /Documentation/fault-injection/fault-injection.rst | |
| parent | 91a1265cacdd96229304adddf18dcf64a4b8c040 (diff) | |
docs: fault-injection: fix non-working usage of negative values
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@sang-engineering.com>
Link: https://lore.kernel.org/r/20210603125841.27436-1-wsa+renesas@sang-engineering.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/fault-injection/fault-injection.rst')
| -rw-r--r-- | Documentation/fault-injection/fault-injection.rst | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/Documentation/fault-injection/fault-injection.rst b/Documentation/fault-injection/fault-injection.rst index 31ecfe44e5b4..f47d05ed0d94 100644 --- a/Documentation/fault-injection/fault-injection.rst +++ b/Documentation/fault-injection/fault-injection.rst @@ -78,8 +78,10 @@ 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: @@ -167,11 +169,13 @@ 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 ^^^^^^^^^^^ @@ -255,7 +259,7 @@ 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 @@ -309,7 +313,7 @@ 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 @@ -336,11 +340,11 @@ 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 |