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cgroups: remove some redundant NULL checks

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- In cgroup_clone(), if vfs_mkdir() returns successfully,
  dentry->d_fsdata will be the pointer to the newly created
  cgroup and won't be NULL.

- a cgroup file's dentry->d_fsdata won't be NULL, guaranteed
  by cgroup_add_file().

- When walking through the subsystems of a cgroup_fs (using
  for_each_subsys), cgrp->subsys[ss->subsys_id] won't be NULL,
  guaranteed by cgroup_create().

(Also remove 2 unused variables in cgroup_rmdir().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan 2009-01-07 18:07:33 -08:00 committed by Linus Torvalds
parent 18e7f1f0d3
commit 75139b8274
1 changed files with 7 additions and 22 deletions
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29
kernel/cgroup.c
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@ -586,7 +586,7 @@ static void cgroup_call_pre_destroy(struct cgroup *cgrp)
{
struct cgroup_subsys *ss;
for_each_subsys(cgrp->root, ss)
if (ss->pre_destroy && cgrp->subsys[ss->subsys_id])
if (ss->pre_destroy)
ss->pre_destroy(ss, cgrp);
return;
}
@ -610,10 +610,8 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
/*
* Release the subsystem state objects.
*/
for_each_subsys(cgrp->root, ss) {
if (cgrp->subsys[ss->subsys_id])
ss->destroy(ss, cgrp);
}
for_each_subsys(cgrp->root, ss)
ss->destroy(ss, cgrp);
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
@ -1445,7 +1443,7 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
struct cftype *cft = __d_cft(file->f_dentry);
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
if (!cft || cgroup_is_removed(cgrp))
if (cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->write)
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
@ -1490,7 +1488,7 @@ static ssize_t cgroup_file_read(struct file *file, char __user *buf,
struct cftype *cft = __d_cft(file->f_dentry);
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
if (!cft || cgroup_is_removed(cgrp))
if (cgroup_is_removed(cgrp))
return -ENODEV;
if (cft->read)
@ -1554,10 +1552,8 @@ static int cgroup_file_open(struct inode *inode, struct file *file)
err = generic_file_open(inode, file);
if (err)
return err;
cft = __d_cft(file->f_dentry);
if (!cft)
return -ENODEV;
if (cft->read_map || cft->read_seq_string) {
struct cgroup_seqfile_state *state =
kzalloc(sizeof(*state), GFP_USER);
@ -2463,8 +2459,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
struct cgroup *cgrp = dentry->d_fsdata;
struct dentry *d;
struct cgroup *parent;
struct super_block *sb;
struct cgroupfs_root *root;
/* the vfs holds both inode->i_mutex already */
@ -2487,8 +2481,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
mutex_lock(&cgroup_mutex);
parent = cgrp->parent;
root = cgrp->root;
sb = root->sb;
if (atomic_read(&cgrp->count)
|| !list_empty(&cgrp->children)
@ -2937,7 +2929,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
}
/* Create the cgroup directory, which also creates the cgroup */
ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755);
ret = vfs_mkdir(inode, dentry, 0755);
child = __d_cgrp(dentry);
dput(dentry);
if (ret) {
@ -2947,13 +2939,6 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
goto out_release;
}
if (!child) {
printk(KERN_INFO
"Couldn't find new cgroup %s\n", nodename);
ret = -ENOMEM;
goto out_release;
}
/* The cgroup now exists. Retake cgroup_mutex and check
* that we're still in the same state that we thought we
* were. */