x86/intel_rdt: Fix a silent failure when writing zero value schemata
PATCH 1/1 x86/intel_rdt: Fix a silent failure when writing zero value schemata
From: Xiaochen Shen <[email protected]>
When writing an invalid schemata with no domain values (e.g., "(L3|MB):"), we get a silent failure.
There isn't a good reason to allow writing zero value, we'd better return error and set diagnostics information in last_cmd_status.
1. 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
2. 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 zero value. ]
---
[apply to TIP x86/cache]
arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c | 5 +++++ 1 file changed, 5 insertions(+)
arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c +5 -0
@@ -257,6 +257,11 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of, ret = -EINVAL ; goto out; } +if (tok[0 ] =='\0' ) { +rdt_last_cmd_printf ("Missing '%s' value\n" , resname); + ret = -EINVAL ; + goto out; + } ret =rdtgroup_parse_resource (resname, tok, closid);if (ret) goto out;
Signature · 1 line
2.14.1
tip-bot for Xiaochen Shen
merge botx86/intel_rdt: Fix a silent failure when writing zero value schemata
Commit-ID: 2244645ab194fe45ffcbaa08f235c8f0c7fb54fc Gitweb: https://git.kernel.org/tip/2244645ab194fe45ffcbaa08f235c8f0c7fb54fc Author: Xiaochen Shen <[email protected]> AuthorDate: Fri, 10 Nov 2017 11:16:24 -0800 Committer: Thomas Gleixner <[email protected]> CommitDate: Sun, 12 Nov 2017 09:01:40 +0100
x86/intel_rdt: Fix a silent failure when writing zero value schemata
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. ]
--- arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c | 5 +++++ 1 file changed, 5 insertions(+)
arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c +5 -0
@@ -257,6 +257,11 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of, ret = -EINVAL ; goto out; } +if (tok[0 ] =='\0' ) { +rdt_last_cmd_printf ("Missing '%s' value\n" , resname); + ret = -EINVAL ; + goto out; + } ret =rdtgroup_parse_resource (resname, tok, closid);if (ret) goto out;