[PATCH 2/2] cpuset: simplify proc_cpuset_show()

[Zefan Li]

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

Signed-off-by: Zefan Li <lize...@huawei.com>
---
 fs/proc/base.c         | 20 ++------------------
 include/linux/cpuset.h |  3 ++-
 kernel/cpuset.c        | 15 +++------------
 3 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6b96892..4e8aa35 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -376,22 +376,6 @@ static const struct file_operations proc_lstats_operations 
= {
 
 #endif
 
-#ifdef CONFIG_PROC_PID_CPUSET
-
-static int cpuset_open(struct inode *inode, struct file *file)
-{
-       struct pid *pid = PROC_I(inode)->pid;
-       return single_open(file, proc_cpuset_show, pid);
-}
-
-static const struct file_operations proc_cpuset_operations = {
-       .open           = cpuset_open,
-       .read           = seq_read,
-       .llseek         = seq_lseek,
-       .release        = single_release,
-};
-#endif
-
 static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
                          struct pid *pid, struct task_struct *task)
 {
@@ -2558,7 +2542,7 @@ static const struct pid_entry tgid_base_stuff[] = {
        REG("latency",  S_IRUGO, proc_lstats_operations),
 #endif
 #ifdef CONFIG_PROC_PID_CPUSET
-       REG("cpuset",     S_IRUGO, proc_cpuset_operations),
+       ONE("cpuset",     S_IRUGO, proc_cpuset_show),
 #endif
 #ifdef CONFIG_CGROUPS
        ONE("cgroup",  S_IRUGO, proc_cgroup_show),
@@ -2904,7 +2888,7 @@ static const struct pid_entry tid_base_stuff[] = {
        REG("latency",  S_IRUGO, proc_lstats_operations),
 #endif
 #ifdef CONFIG_PROC_PID_CPUSET
-       REG("cpuset",    S_IRUGO, proc_cpuset_operations),
+       ONE("cpuset",    S_IRUGO, proc_cpuset_show),
 #endif
 #ifdef CONFIG_CGROUPS
        ONE("cgroup",  S_IRUGO, proc_cgroup_show),
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index ade2390..0d4e067 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -86,7 +86,8 @@ extern void __cpuset_memory_pressure_bump(void);
 
 extern void cpuset_task_status_allowed(struct seq_file *m,
                                        struct task_struct *task);
-extern int proc_cpuset_show(struct seq_file *, void *);
+extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
+                           struct pid *pid, struct task_struct *tsk);
 
 extern int cpuset_mem_spread_node(void);
 extern int cpuset_slab_spread_node(void);
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 22874d7..a37f4ed 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2729,10 +2729,9 @@ void __cpuset_memory_pressure_bump(void)
  *    and we take cpuset_mutex, keeping cpuset_attach() from changing it
  *    anyway.
  */
-int proc_cpuset_show(struct seq_file *m, void *unused_v)
+int proc_cpuset_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, *p;
        struct cgroup_subsys_state *css;
        int retval;
@@ -2742,24 +2741,16 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
        if (!buf)
                goto out;
 
-       retval = -ESRCH;
-       pid = m->private;
-       tsk = get_pid_task(pid, PIDTYPE_PID);
-       if (!tsk)
-               goto out_free;
-
        retval = -ENAMETOOLONG;
        rcu_read_lock();
        css = task_css(tsk, cpuset_cgrp_id);
        p = cgroup_path(css->cgroup, buf, PATH_MAX);
        rcu_read_unlock();
        if (!p)
-               goto out_put_task;
+               goto out_free;
        seq_puts(m, p);
        seq_putc(m, '\n');
        retval = 0;
-out_put_task:
-       put_task_struct(tsk);
 out_free:
        kfree(buf);
 out:
-- 
1.8.0.2

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