Writing an invalid schemata with no domain values (e.g., "(L3|MB):"),
results in a silent failure, i.e. the last_cmd_status returns OK,
Check for an empty value and set the result string with a proper error
message and return -EINVAL.
Before the fix:
# mkdir /sys/fs/resctrl/p1
# echo "L3:" > /sys/fs/resctrl/p1/schemata
(silent failure)
# cat /sys/fs/resctrl/info/last_cmd_status
ok
# echo "MB:" > /sys/fs/resctrl/p1/schemata
(silent failure)
# cat /sys/fs/resctrl/info/last_cmd_status
ok
After the fix:
# mkdir /sys/fs/resctrl/p1
# echo "L3:" > /sys/fs/resctrl/p1/schemata
-bash: echo: write error: Invalid argument
# cat /sys/fs/resctrl/info/last_cmd_status
Missing 'L3' value
# echo "MB:" > /sys/fs/resctrl/p1/schemata
-bash: echo: write error: Invalid argument
# cat /sys/fs/resctrl/info/last_cmd_status
Missing 'MB' value
[ Tony: This is an unintended side effect of the patch earlier to allow the
user to just write the value they want to change. While allowing
user to specify less than all of the values, it also allows an
empty value. ]
Fixes: c4026b7b95 ("x86/intel_rdt: Implement "update" mode when writing schemata file")
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lkml.kernel.org/r/20171110191624.20280-1-tony.luck@intel.com
2244645ab1