diff options
| -rw-r--r-- | Documentation/cgroups.txt | 22 | ||||
| -rw-r--r-- | kernel/cgroup.c | 36 |
2 files changed, 35 insertions, 23 deletions
diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt index 98a26f81fa7..42d7c4cb39c 100644 --- a/Documentation/cgroups.txt +++ b/Documentation/cgroups.txt @@ -456,7 +456,7 @@ methods are create/destroy. Any others that are null are presumed to be successful no-ops. struct cgroup_subsys_state *create(struct cgroup *cont) -LL=cgroup_mutex +(cgroup_mutex held by caller) Called to create a subsystem state object for a cgroup. The subsystem should allocate its subsystem state object for the passed @@ -471,14 +471,19 @@ it's the root of the hierarchy) and may be an appropriate place for initialization code. void destroy(struct cgroup *cont) -LL=cgroup_mutex +(cgroup_mutex held by caller) -The cgroup system is about to destroy the passed cgroup; the -subsystem should do any necessary cleanup +The cgroup system is about to destroy the passed cgroup; the subsystem +should do any necessary cleanup and free its subsystem state +object. By the time this method is called, the cgroup has already been +unlinked from the file system and from the child list of its parent; +cgroup->parent is still valid. (Note - can also be called for a +newly-created cgroup if an error occurs after this subsystem's +create() method has been called for the new cgroup). int can_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct task_struct *task) -LL=cgroup_mutex +(cgroup_mutex held by caller) Called prior to moving a task into a cgroup; if the subsystem returns an error, this will abort the attach operation. If a NULL @@ -489,25 +494,20 @@ remain valid while the caller holds cgroup_mutex. void attach(struct cgroup_subsys *ss, struct cgroup *cont, struct cgroup *old_cont, struct task_struct *task) -LL=cgroup_mutex - Called after the task has been attached to the cgroup, to allow any post-attachment activity that requires memory allocations or blocking. void fork(struct cgroup_subsy *ss, struct task_struct *task) -LL=callback_mutex, maybe read_lock(tasklist_lock) Called when a task is forked into a cgroup. Also called during registration for all existing tasks. void exit(struct cgroup_subsys *ss, struct task_struct *task) -LL=callback_mutex Called during task exit int populate(struct cgroup_subsys *ss, struct cgroup *cont) -LL=none Called after creation of a cgroup to allow a subsystem to populate the cgroup directory with file entries. The subsystem should make @@ -524,7 +524,7 @@ example in cpusets, no task may attach before 'cpus' and 'mems' are set up. void bind(struct cgroup_subsys *ss, struct cgroup *root) -LL=callback_mutex +(cgroup_mutex held by caller) Called when a cgroup subsystem is rebound to a different hierarchy and root cgroup. Currently this will only involve movement between diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7d207414f2c..b0fee0c6144 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -591,6 +591,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) /* is dentry a directory ? if so, kfree() associated cgroup */ if (S_ISDIR(inode->i_mode)) { struct cgroup *cgrp = dentry->d_fsdata; + struct cgroup_subsys *ss; BUG_ON(!(cgroup_is_removed(cgrp))); /* It's possible for external users to be holding css * reference counts on a cgroup; css_put() needs to @@ -599,6 +600,23 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) * queue the cgroup to be handled by the release * agent */ synchronize_rcu(); + + mutex_lock(&cgroup_mutex); + /* + * Release the subsystem state objects. + */ + for_each_subsys(cgrp->root, ss) { + if (cgrp->subsys[ss->subsys_id]) + ss->destroy(ss, cgrp); + } + + cgrp->root->number_of_cgroups--; + mutex_unlock(&cgroup_mutex); + + /* Drop the active superblock reference that we took when we + * created the cgroup */ + deactivate_super(cgrp->root->sb); + kfree(cgrp); } iput(inode); @@ -1330,6 +1348,10 @@ static ssize_t cgroup_common_file_write(struct cgroup *cgrp, mutex_lock(&cgroup_mutex); + /* + * This was already checked for in cgroup_file_write(), but + * check again now we're holding cgroup_mutex. + */ if (cgroup_is_removed(cgrp)) { retval = -ENODEV; goto out2; @@ -1370,7 +1392,7 @@ 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) + if (!cft || cgroup_is_removed(cgrp)) return -ENODEV; if (cft->write) return cft->write(cgrp, cft, file, buf, nbytes, ppos); @@ -1440,7 +1462,7 @@ 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) + if (!cft || cgroup_is_removed(cgrp)) return -ENODEV; if (cft->read) @@ -2120,7 +2142,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) struct cgroup *cgrp = dentry->d_fsdata; struct dentry *d; struct cgroup *parent; - struct cgroup_subsys *ss; struct super_block *sb; struct cgroupfs_root *root; @@ -2145,11 +2166,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) return -EBUSY; } - for_each_subsys(root, ss) { - if (cgrp->subsys[ss->subsys_id]) - ss->destroy(ss, cgrp); - } - spin_lock(&release_list_lock); set_bit(CGRP_REMOVED, &cgrp->flags); if (!list_empty(&cgrp->release_list)) @@ -2164,15 +2180,11 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) cgroup_d_remove_dir(d); dput(d); - root->number_of_cgroups--; set_bit(CGRP_RELEASABLE, &parent->flags); check_for_release(parent); mutex_unlock(&cgroup_mutex); - /* Drop the active superblock reference that we took when we - * created the cgroup */ - deactivate_super(sb); return 0; } |