openwrt/target/linux/layerscape/patches-5.4/303-core-0004-cgroup-bfq-revert-bfq.weight-symlink-change.patch

From b7f71899fbdba1cac6773a62ed4ea841b7eda6b0 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 10 Jun 2019 03:35:41 -0600
Subject: [PATCH] cgroup/bfq: revert bfq.weight symlink change

There's some discussion on how to do this the best, and Tejun prefers
that BFQ just create the file itself instead of having cgroups support
a symlink feature.

Hence revert commit 54b7b868e826 and 19e9da9e86c4 for 5.2, and this
can be done properly for 5.3.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit cf8929885de318c0bf73438c9e5dde59d6536f7c)
Signed-off-by: Li Yang <leoyang.li@nxp.com>
---
 include/linux/cgroup-defs.h |  3 ---
 kernel/cgroup/cgroup.c      | 33 ++++-----------------------------
 2 files changed, 4 insertions(+), 32 deletions(-)

--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -106,8 +106,6 @@ enum {
 	CFTYPE_WORLD_WRITABLE	= (1 << 4),	/* (DON'T USE FOR NEW FILES) S_IWUGO */
 	CFTYPE_DEBUG		= (1 << 5),	/* create when cgroup_debug */
 
-	CFTYPE_SYMLINKED	= (1 << 6),	/* pointed to by symlink too */
-
 	/* internal flags, do not use outside cgroup core proper */
 	__CFTYPE_ONLY_ON_DFL	= (1 << 16),	/* only on default hierarchy */
 	__CFTYPE_NOT_ON_DFL	= (1 << 17),	/* not on default hierarchy */
@@ -546,7 +544,6 @@ struct cftype {
 	 * end of cftype array.
 	 */
 	char name[MAX_CFTYPE_NAME];
-	char link_name[MAX_CFTYPE_NAME];
 	unsigned long private;
 
 	/*
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1465,8 +1465,8 @@ struct cgroup *task_cgroup_from_root(str
 
 static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
 
-static char *cgroup_fill_name(struct cgroup *cgrp, const struct cftype *cft,
-			      char *buf, bool write_link_name)
+static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+			      char *buf)
 {
 	struct cgroup_subsys *ss = cft->ss;
 
@@ -1476,26 +1476,13 @@ static char *cgroup_fill_name(struct cgr
 
 		snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s",
 			 dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
-			 write_link_name ? cft->link_name : cft->name);
+			 cft->name);
 	} else {
-		strscpy(buf, write_link_name ? cft->link_name : cft->name,
-			CGROUP_FILE_NAME_MAX);
+		strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
 	}
 	return buf;
 }
 
-static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
-			      char *buf)
-{
-	return cgroup_fill_name(cgrp, cft, buf, false);
-}
-
-static char *cgroup_link_name(struct cgroup *cgrp, const struct cftype *cft,
-			      char *buf)
-{
-	return cgroup_fill_name(cgrp, cft, buf, true);
-}
-
 /**
  * cgroup_file_mode - deduce file mode of a control file
  * @cft: the control file in question
@@ -1654,9 +1641,6 @@ static void cgroup_rm_file(struct cgroup
 	}
 
 	kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
-	if (cft->flags & CFTYPE_SYMLINKED)
-		kernfs_remove_by_name(cgrp->kn,
-				      cgroup_link_name(cgrp, cft, name));
 }
 
 /**
@@ -3912,7 +3896,6 @@ static int cgroup_add_file(struct cgroup
 {
 	char name[CGROUP_FILE_NAME_MAX];
 	struct kernfs_node *kn;
-	struct kernfs_node *kn_link;
 	struct lock_class_key *key = NULL;
 	int ret;
 
@@ -3943,14 +3926,6 @@ static int cgroup_add_file(struct cgroup
 		spin_unlock_irq(&cgroup_file_kn_lock);
 	}
 
-	if (cft->flags & CFTYPE_SYMLINKED) {
-		kn_link = kernfs_create_link(cgrp->kn,
-					     cgroup_link_name(cgrp, cft, name),
-					     kn);
-		if (IS_ERR(kn_link))
-			return PTR_ERR(kn_link);
-	}
-
 	return 0;
 }