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authorLi Zefan <lizf@cn.fujitsu.com>2009-01-07 21:07:33 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-08 11:31:01 -0500
commit75139b8274c3e30354daea623f14b43a482a0bb5 (patch)
tree0da75602e260cd565d9f8c03d789744448966171 /kernel/cgroup.c
parent18e7f1f0d34be4a39f7f47324a3e26b43fddb714 (diff)
cgroups: remove some redundant NULL checks
- 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>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c29
1 files changed, 7 insertions, 22 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index f221446aa02d..220e0fd659fa 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -586,7 +586,7 @@ static void cgroup_call_pre_destroy(struct cgroup *cgrp)
586{ 586{
587 struct cgroup_subsys *ss; 587 struct cgroup_subsys *ss;
588 for_each_subsys(cgrp->root, ss) 588 for_each_subsys(cgrp->root, ss)
589 if (ss->pre_destroy && cgrp->subsys[ss->subsys_id]) 589 if (ss->pre_destroy)
590 ss->pre_destroy(ss, cgrp); 590 ss->pre_destroy(ss, cgrp);
591 return; 591 return;
592} 592}
@@ -610,10 +610,8 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
610 /* 610 /*
611 * Release the subsystem state objects. 611 * Release the subsystem state objects.
612 */ 612 */
613 for_each_subsys(cgrp->root, ss) { 613 for_each_subsys(cgrp->root, ss)
614 if (cgrp->subsys[ss->subsys_id]) 614 ss->destroy(ss, cgrp);
615 ss->destroy(ss, cgrp);
616 }
617 615
618 cgrp->root->number_of_cgroups--; 616 cgrp->root->number_of_cgroups--;
619 mutex_unlock(&cgroup_mutex); 617 mutex_unlock(&cgroup_mutex);
@@ -1445,7 +1443,7 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
1445 struct cftype *cft = __d_cft(file->f_dentry); 1443 struct cftype *cft = __d_cft(file->f_dentry);
1446 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); 1444 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
1447 1445
1448 if (!cft || cgroup_is_removed(cgrp)) 1446 if (cgroup_is_removed(cgrp))
1449 return -ENODEV; 1447 return -ENODEV;
1450 if (cft->write) 1448 if (cft->write)
1451 return cft->write(cgrp, cft, file, buf, nbytes, ppos); 1449 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,
1490 struct cftype *cft = __d_cft(file->f_dentry); 1488 struct cftype *cft = __d_cft(file->f_dentry);
1491 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); 1489 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
1492 1490
1493 if (!cft || cgroup_is_removed(cgrp)) 1491 if (cgroup_is_removed(cgrp))
1494 return -ENODEV; 1492 return -ENODEV;
1495 1493
1496 if (cft->read) 1494 if (cft->read)
@@ -1554,10 +1552,8 @@ static int cgroup_file_open(struct inode *inode, struct file *file)
1554 err = generic_file_open(inode, file); 1552 err = generic_file_open(inode, file);
1555 if (err) 1553 if (err)
1556 return err; 1554 return err;
1557
1558 cft = __d_cft(file->f_dentry); 1555 cft = __d_cft(file->f_dentry);
1559 if (!cft) 1556
1560 return -ENODEV;
1561 if (cft->read_map || cft->read_seq_string) { 1557 if (cft->read_map || cft->read_seq_string) {
1562 struct cgroup_seqfile_state *state = 1558 struct cgroup_seqfile_state *state =
1563 kzalloc(sizeof(*state), GFP_USER); 1559 kzalloc(sizeof(*state), GFP_USER);
@@ -2463,8 +2459,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
2463 struct cgroup *cgrp = dentry->d_fsdata; 2459 struct cgroup *cgrp = dentry->d_fsdata;
2464 struct dentry *d; 2460 struct dentry *d;
2465 struct cgroup *parent; 2461 struct cgroup *parent;
2466 struct super_block *sb;
2467 struct cgroupfs_root *root;
2468 2462
2469 /* the vfs holds both inode->i_mutex already */ 2463 /* the vfs holds both inode->i_mutex already */
2470 2464
@@ -2487,8 +2481,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
2487 2481
2488 mutex_lock(&cgroup_mutex); 2482 mutex_lock(&cgroup_mutex);
2489 parent = cgrp->parent; 2483 parent = cgrp->parent;
2490 root = cgrp->root;
2491 sb = root->sb;
2492 2484
2493 if (atomic_read(&cgrp->count) 2485 if (atomic_read(&cgrp->count)
2494 || !list_empty(&cgrp->children) 2486 || !list_empty(&cgrp->children)
@@ -2937,7 +2929,7 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
2937 } 2929 }
2938 2930
2939 /* Create the cgroup directory, which also creates the cgroup */ 2931 /* Create the cgroup directory, which also creates the cgroup */
2940 ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755); 2932 ret = vfs_mkdir(inode, dentry, 0755);
2941 child = __d_cgrp(dentry); 2933 child = __d_cgrp(dentry);
2942 dput(dentry); 2934 dput(dentry);
2943 if (ret) { 2935 if (ret) {
@@ -2947,13 +2939,6 @@ int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
2947 goto out_release; 2939 goto out_release;
2948 } 2940 }
2949 2941
2950 if (!child) {
2951 printk(KERN_INFO
2952 "Couldn't find new cgroup %s\n", nodename);
2953 ret = -ENOMEM;
2954 goto out_release;
2955 }
2956
2957 /* The cgroup now exists. Retake cgroup_mutex and check 2942 /* The cgroup now exists. Retake cgroup_mutex and check
2958 * that we're still in the same state that we thought we 2943 * that we're still in the same state that we thought we
2959 * were. */ 2944 * were. */