[PATCH] cgroup: clean up obsolete code and comment

[PATCH] cgroup: clean up obsolete code and comment

[Jianyu Zhan]

This patch purely makes cleanup.

1. parse_cgroupfs_options() no longer takes refcounts on
   subsystems to be used, update its comment.
2. cgroup_pidlist_seq_operations has no more user, remove it.
3. s/pr_warning/pr_warn/g, suggested by scripts/checkpatch.pl.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
---
 kernel/cgroup.c | 31 +++++++++----------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8c314dd..ec5bfb2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1127,9 +1127,9 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
 		 * Just warn about it and continue.
 		 */
 		if (cgrp_dfl_root_visible) {
-			pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n",
+			pr_warn("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n",
 				   ret, ss_mask);
-			pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n");
+			pr_warn("cgroup: you may retry by moving them to a different hierarchy and unbinding\n");
 		}
 	}
 
@@ -1223,10 +1223,8 @@ struct cgroup_sb_opts {
 };
 
 /*
- * Convert a hierarchy specifier into a bitmask of subsystems and
- * flags. Call with cgroup_mutex held to protect the cgroup_subsys[]
- * array. This function takes refcounts on subsystems to be used, unless it
- * returns error, in which case no refcounts are taken.
+ * Convert a hierarchy specifier into a bitmask of subsystems and flags.
+ * Call with cgroup_mutex held to protect the cgroup_subsys[] array.
  */
 static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 {
@@ -1332,7 +1330,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
 	/* Consistency checks */
 
 	if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
-		pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
+		pr_warn("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
 
 		if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) ||
 		    opts->cpuset_clone_children || opts->release_agent ||
@@ -1396,7 +1394,7 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
 		goto out_unlock;
 
 	if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
-		pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
+		pr_warn("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
 			   task_tgid_nr(current), current->comm);
 
 	added_mask = opts.subsys_mask & ~root->subsys_mask;
@@ -1678,7 +1676,7 @@ retry:
 				ret = -EINVAL;
 				goto out_unlock;
 			} else {
-				pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
+				pr_warn("cgroup: new mount options do not match the existing superblock, will be ignored\n");
 			}
 		}
 
@@ -3890,17 +3888,6 @@ static int cgroup_pidlist_show(struct seq_file *s, void *v)
 	return seq_printf(s, "%d\n", *(int *)v);
 }
 
-/*
- * seq_operations functions for iterating on pidlists through seq_file -
- * independent of whether it's tasks or procs
- */
-static const struct seq_operations cgroup_pidlist_seq_operations = {
-	.start = cgroup_pidlist_start,
-	.stop = cgroup_pidlist_stop,
-	.next = cgroup_pidlist_next,
-	.show = cgroup_pidlist_show,
-};
-
 static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
 					 struct cftype *cft)
 {
@@ -4189,10 +4176,10 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
 
 	if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
 	    parent->parent) {
-		pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
+		pr_warn("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
 			   current->comm, current->pid, ss->name);
 		if (!strcmp(ss->name, "memory"))
-			pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
+			pr_warn("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
 		ss->warned_broken_hierarchy = true;
 	}
 
-- 
1.9.0.GIT

Re: [PATCH] cgroup: clean up obsolete code and comment

[Tejun Heo]

On Thu, Apr 17, 2014 at 10:14:16PM +0800, Jianyu Zhan wrote:
> This patch purely makes cleanup.
> 
> 1. parse_cgroupfs_options() no longer takes refcounts on
>    subsystems to be used, update its comment.

And cgroup_subsys[] doesn't require cgroup_mutex protection anymore.
That comment and BUG_ON(!mutex_is_locked()) can be removed.  Can you
please separate these out into a separate patch?

> 2. cgroup_pidlist_seq_operations has no more user, remove it.
> 3. s/pr_warning/pr_warn/g, suggested by scripts/checkpatch.pl.

And let's put 2 and 3 in separate patches too.

> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>

Also, please regenerate the patches on top of the following branch.

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-populated-v2

Thanks.

-- 
tejun

Re: [PATCH] cgroup: clean up obsolete code and comment

[Jianyu Zhan]

On Thu, Apr 17, 2014 at 10:19 PM, Tejun Heo <tj@kernel.org> wrote:
> And cgroup_subsys[] doesn't require cgroup_mutex protection anymore.
> That comment and BUG_ON(!mutex_is_locked()) can be removed.  Can you
> please separate these out into a separate patch?
>
>> 2. cgroup_pidlist_seq_operations has no more user, remove it.
>> 3. s/pr_warning/pr_warn/g, suggested by scripts/checkpatch.pl.
>
> And let's put 2 and 3 in separate patches too.
>
>> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
>
> Also, please regenerate the patches on top of the following branch.
>
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-populated-v2

Ok. This patch is based on review-populated-v2 already.


Thanks,
Jianyu Zhan