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Subject[PATCH v15 10/12] cpuset: Use descriptive text when reading/writing cpuset.sched.partition
Date
Currently, cpuset.sched.partition returns the values, 0, 1 or -1 on
read. A person who is not familiar with the partition code may not
understand what they mean.

In order to make cpuset.sched.partition more user-friendly, it will
now display the following descriptive text on read:

"root" - A partition root (top cpuset of a partition)
"member" - A non-root member of a partition
"root invalid" - An invalid partition root

Note that there is at least one partition in the whole cgroup hierarchy.
The top cpuset is the root of that partition. The rests are either a
root if it starts a new partition or a member of a partition.

The cpuset.sched.partition file will now also accept "root" and
"member" besides 1 and 0 as valid input values. The "root invalid"
value is internal only and cannot be written to the file.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset.c | 58 ++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 51 insertions(+), 7 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index fc1a809..c739fda 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2278,9 +2278,6 @@ static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
retval = update_relax_domain_level(cs, val);
break;
- case FILE_PARTITION_ROOT:
- retval = update_prstate(cs, val);
- break;
default:
retval = -EINVAL;
break;
@@ -2431,8 +2428,6 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
switch (type) {
case FILE_SCHED_RELAX_DOMAIN_LEVEL:
return cs->relax_domain_level;
- case FILE_PARTITION_ROOT:
- return cs->partition_root_state;
default:
BUG();
}
@@ -2441,6 +2436,55 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
return 0;
}

+static int sched_partition_show(struct seq_file *seq, void *v)
+{
+ struct cpuset *cs = css_cs(seq_css(seq));
+
+ switch (cs->partition_root_state) {
+ case PRS_ENABLED:
+ seq_puts(seq, "root\n");
+ break;
+ case PRS_DISABLED:
+ seq_puts(seq, "member\n");
+ break;
+ case PRS_ERROR:
+ seq_puts(seq, "root invalid\n");
+ break;
+ }
+ return 0;
+}
+
+static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cpuset *cs = css_cs(of_css(of));
+ int val;
+ int retval = -ENODEV;
+
+ buf = strstrip(buf);
+
+ /*
+ * Convert "root"/"1" to 1, and convert "member"/"0" to 0.
+ */
+ if (!strcmp(buf, "root") || !strcmp(buf, "1"))
+ val = PRS_ENABLED;
+ else if (!strcmp(buf, "member") || !strcmp(buf, "0"))
+ val = PRS_DISABLED;
+ else
+ return -EINVAL;
+
+ css_get(&cs->css);
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs))
+ goto out_unlock;
+
+ retval = update_prstate(cs, val);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ css_put(&cs->css);
+ return retval ?: nbytes;
+}
+
/*
* for the common functions, 'private' gives the type of file
*/
@@ -2584,8 +2628,8 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)

{
.name = "sched.partition",
- .read_s64 = cpuset_read_s64,
- .write_s64 = cpuset_write_s64,
+ .seq_show = sched_partition_show,
+ .write = sched_partition_write,
.private = FILE_PARTITION_ROOT,
.flags = CFTYPE_NOT_ON_ROOT,
},
--
1.8.3.1
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