From 35ac1184244f1329783e1d897f74926d8bb1103a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 12 Jan 2019 00:20:54 -0500 Subject: cgroup: saner refcounting for cgroup_root * make the reference from superblock to cgroup_root counting - do cgroup_put() in cgroup_kill_sb() whether we'd done percpu_ref_kill() or not; matching grab is done when we allocate a new root. That gives the same refcounting rules for all callers of cgroup_do_mount() - a reference to cgroup_root has been grabbed by caller and it either is transferred to new superblock or dropped. * have cgroup_kill_sb() treat an already killed refcount as "just don't bother killing it, then". * after successful cgroup_do_mount() have cgroup1_mount() recheck if we'd raced with mount/umount from somebody else and cgroup_root got killed. In that case we drop the superblock and bugger off with -ERESTARTSYS, same as if we'd found it in the list already dying. * don't bother with delayed initialization of refcount - it's unreliable and not needed. No need to prevent attempts to bump the refcount if we find cgroup_root of another mount in progress - sget will reuse an existing superblock just fine and if the other sb manages to die before we get there, we'll catch that immediately after cgroup_do_mount(). * don't bother with kernfs_pin_sb() - no need for doing that either. Signed-off-by: Al Viro --- kernel/cgroup/cgroup-internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/cgroup/cgroup-internal.h') diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index c950864016e2..c9a35f09e4b9 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -198,7 +198,7 @@ int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen, void cgroup_free_root(struct cgroup_root *root); void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts); -int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags); +int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask); int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask); struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags, struct cgroup_root *root, unsigned long magic, -- cgit v1.2.3-70-g09d2