diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 0f3527d6184..2097684cf19 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -255,12 +255,17 @@ int cgroup_lock_is_held(void) EXPORT_SYMBOL_GPL(cgroup_lock_is_held); +static int css_unbias_refcnt(int refcnt) +{ + return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; +} + /* the current nr of refs, always >= 0 whether @css is deactivated or not */ static int css_refcnt(struct cgroup_subsys_state *css) { int v = atomic_read(&css->refcnt); - return v >= 0 ? v : v - CSS_DEACT_BIAS; + return css_unbias_refcnt(v); } /* convenient tests for these bits */ @@ -896,10 +901,13 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) mutex_unlock(&cgroup_mutex); /* - * Drop the active superblock reference that we took when we - * created the cgroup + * We want to drop the active superblock reference from the + * cgroup creation after all the dentry refs are gone - + * kill_sb gets mighty unhappy otherwise. Mark + * dentry->d_fsdata with cgroup_diput() to tell + * cgroup_d_release() to call deactivate_super(). */ - deactivate_super(cgrp->root->sb); + dentry->d_fsdata = cgroup_diput; /* * if we're getting rid of the cgroup, refcount should ensure @@ -925,6 +933,13 @@ static int cgroup_delete(const struct dentry *d) return 1; } +static void cgroup_d_release(struct dentry *dentry) +{ + /* did cgroup_diput() tell me to deactivate super? */ + if (dentry->d_fsdata == cgroup_diput) + deactivate_super(dentry->d_sb); +} + static void remove_dir(struct dentry *d) { struct dentry *parent = dget(d->d_parent); @@ -1532,6 +1547,7 @@ static int cgroup_get_rootdir(struct super_block *sb) static const struct dentry_operations cgroup_dops = { .d_iput = cgroup_diput, .d_delete = cgroup_delete, + .d_release = cgroup_d_release, }; struct inode *inode = @@ -4971,10 +4987,12 @@ EXPORT_SYMBOL_GPL(__css_tryget); void __css_put(struct cgroup_subsys_state *css) { struct cgroup *cgrp = css->cgroup; + int v; rcu_read_lock(); - atomic_dec(&css->refcnt); - switch (css_refcnt(css)) { + v = css_unbias_refcnt(atomic_dec_return(&css->refcnt)); + + switch (v) { case 1: if (notify_on_release(cgrp)) { set_bit(CGRP_RELEASABLE, &cgrp->flags); |