On 1/17/25 5:44 AM, Michal Koutný wrote:
The cpuset file is a legacy attribute that is bound primarily to cpuset
v1 hierarchy (equivalent information is available in /proc/$pid/cgroup path
on the unified hierarchy in conjunction with respective
cgroup.controllers showing where cpuset controller is enabled).
Followup to commit b0ced9d378d49 ("cgroup/cpuset: move v1 interfaces to
cpuset-v1.c") and hide CONFIG_PROC_PID_CPUSET under CONFIG_CPUSETS_V1.
Drop an obsolete comment too.
Signed-off-by: Michal Koutný <mkoutny@xxxxxxxx>
---
init/Kconfig | 5 +++--
kernel/cgroup/cpuset-v1.c | 40 +++++++++++++++++++++++++++++++++++
kernel/cgroup/cpuset.c | 44 ---------------------------------------
3 files changed, 43 insertions(+), 46 deletions(-)
v2 changes:
- explicitly say what's part of CPUSETS_V1
- commit message wrt effective paths
diff --git a/init/Kconfig b/init/Kconfig
index a20e6efd3f0fb..2f3121c49ed23 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1182,7 +1182,8 @@ config CPUSETS_V1
help
Legacy cgroup v1 cpusets controller which has been deprecated by
cgroup v2 implementation. The v1 is there for legacy applications
- which haven't migrated to the new cgroup v2 interface yet. If you
+ which haven't migrated to the new cgroup v2 interface yet. Legacy
+ interface includes cpuset filesystem and /proc/<pid>/cpuset. If you
do not have any such application then you are completely fine leaving
this option disabled.
@@ -1190,7 +1191,7 @@ config CPUSETS_V1
config PROC_PID_CPUSET
bool "Include legacy /proc/<pid>/cpuset file"
- depends on CPUSETS
+ depends on CPUSETS_V1
default y
config CGROUP_DEVICE
diff --git a/kernel/cgroup/cpuset-v1.c b/kernel/cgroup/cpuset-v1.c
index 25c1d7b77e2f2..fff1a38f2725f 100644
--- a/kernel/cgroup/cpuset-v1.c
+++ b/kernel/cgroup/cpuset-v1.c
@@ -373,6 +373,46 @@ int cpuset1_validate_change(struct cpuset *cur, struct cpuset *trial)
return ret;
}
+#ifdef CONFIG_PROC_PID_CPUSET
+/*
+ * proc_cpuset_show()
+ * - Print tasks cpuset path into seq_file.
+ * - Used for /proc/<pid>/cpuset.
+ */
+int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ char *buf;
+ struct cgroup_subsys_state *css;
+ int retval;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ rcu_read_lock();
+ spin_lock_irq(&css_set_lock);
+ css = task_css(tsk, cpuset_cgrp_id);
+ retval = cgroup_path_ns_locked(css->cgroup, buf, PATH_MAX,
+ current->nsproxy->cgroup_ns);
+ spin_unlock_irq(&css_set_lock);
+ rcu_read_unlock();
+
+ if (retval == -E2BIG)
+ retval = -ENAMETOOLONG;
+ if (retval < 0)
+ goto out_free;
+ seq_puts(m, buf);
+ seq_putc(m, '\n');
+ retval = 0;
+out_free:
+ kfree(buf);
+out:
+ return retval;
+}
+#endif /* CONFIG_PROC_PID_CPUSET */
+
static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
{
struct cpuset *cs = css_cs(css);
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 0f910c828973a..7d6e8db234290 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -4244,50 +4244,6 @@ void cpuset_print_current_mems_allowed(void)
rcu_read_unlock();
}
-#ifdef CONFIG_PROC_PID_CPUSET
-/*
- * proc_cpuset_show()
- * - Print tasks cpuset path into seq_file.
- * - Used for /proc/<pid>/cpuset.
- * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
- * doesn't really matter if tsk->cpuset changes after we read it,
- * and we take cpuset_mutex, keeping cpuset_attach() from changing it
- * anyway.
- */
-int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk)
-{
- char *buf;
- struct cgroup_subsys_state *css;
- int retval;
-
- retval = -ENOMEM;
- buf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!buf)
- goto out;
-
- rcu_read_lock();
- spin_lock_irq(&css_set_lock);
- css = task_css(tsk, cpuset_cgrp_id);
- retval = cgroup_path_ns_locked(css->cgroup, buf, PATH_MAX,
- current->nsproxy->cgroup_ns);
- spin_unlock_irq(&css_set_lock);
- rcu_read_unlock();
-
- if (retval == -E2BIG)
- retval = -ENAMETOOLONG;
- if (retval < 0)
- goto out_free;
- seq_puts(m, buf);
- seq_putc(m, '\n');
- retval = 0;
-out_free:
- kfree(buf);
-out:
- return retval;
-}
-#endif /* CONFIG_PROC_PID_CPUSET */
-
/* Display task mems_allowed in /proc/<pid>/status file. */
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
Acked-by: Waiman Long <longman@xxxxxxxxxx>
