[PATCH 1/2] cgroup: simplify proc_cgroup_show()

From: Zefan Li
Date: Thu Sep 18 2014 - 04:03:58 EST


Use the ONE macro instead of REG, and we can simplify proc_cgroup_show().

Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
fs/proc/base.c | 19 ++-----------------
include/linux/cgroup.h | 3 ++-
kernel/cgroup.c | 18 +++---------------
3 files changed, 7 insertions(+), 33 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index baf852b..6b96892 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -376,21 +376,6 @@ static const struct file_operations proc_lstats_operations = {

#endif

-#ifdef CONFIG_CGROUPS
-static int cgroup_open(struct inode *inode, struct file *file)
-{
- struct pid *pid = PROC_I(inode)->pid;
- return single_open(file, proc_cgroup_show, pid);
-}
-
-static const struct file_operations proc_cgroup_operations = {
- .open = cgroup_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
-};
-#endif
-
#ifdef CONFIG_PROC_PID_CPUSET

static int cpuset_open(struct inode *inode, struct file *file)
@@ -2576,7 +2561,7 @@ static const struct pid_entry tgid_base_stuff[] = {
REG("cpuset", S_IRUGO, proc_cpuset_operations),
#endif
#ifdef CONFIG_CGROUPS
- REG("cgroup", S_IRUGO, proc_cgroup_operations),
+ ONE("cgroup", S_IRUGO, proc_cgroup_show),
#endif
ONE("oom_score", S_IRUGO, proc_oom_score),
REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
@@ -2922,7 +2907,7 @@ static const struct pid_entry tid_base_stuff[] = {
REG("cpuset", S_IRUGO, proc_cpuset_operations),
#endif
#ifdef CONFIG_CGROUPS
- REG("cgroup", S_IRUGO, proc_cgroup_operations),
+ ONE("cgroup", S_IRUGO, proc_cgroup_show),
#endif
ONE("oom_score", S_IRUGO, proc_oom_score),
REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f7898e0..a5d9b8f 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -37,7 +37,8 @@ extern void cgroup_exit(struct task_struct *p);
extern int cgroupstats_build(struct cgroupstats *stats,
struct dentry *dentry);

-extern int proc_cgroup_show(struct seq_file *, void *);
+extern int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk);

/* define the enumeration of all cgroup subsystems */
#define SUBSYS(_x) _x ## _cgrp_id,
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1abb554..e91bc3c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5040,12 +5040,9 @@ core_initcall(cgroup_wq_init);
* - Print task's cgroup paths into seq_file, one line for each hierarchy
* - Used for /proc/<pid>/cgroup.
*/
-
-/* TODO: Use a proper seq_file iterator */
-int proc_cgroup_show(struct seq_file *m, void *v)
+int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
{
- struct pid *pid;
- struct task_struct *tsk;
char *buf, *path;
int retval;
struct cgroup_root *root;
@@ -5055,14 +5052,6 @@ int proc_cgroup_show(struct seq_file *m, void *v)
if (!buf)
goto out;

- retval = -ESRCH;
- pid = m->private;
- tsk = get_pid_task(pid, PIDTYPE_PID);
- if (!tsk)
- goto out_free;
-
- retval = 0;
-
mutex_lock(&cgroup_mutex);
down_read(&css_set_rwsem);

@@ -5092,11 +5081,10 @@ int proc_cgroup_show(struct seq_file *m, void *v)
seq_putc(m, '\n');
}

+ retval = 0;
out_unlock:
up_read(&css_set_rwsem);
mutex_unlock(&cgroup_mutex);
- put_task_struct(tsk);
-out_free:
kfree(buf);
out:
return retval;
--
1.8.0.2

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