On 2013/7/13 4:38, Tejun Heo wrote: > Module ref handling in cgroup is rather weird. > parse_cgroupfs_options() grabs all the modules for the specified > subsystems. A module ref is kept if the specified subsystem is newly > bound to the hierarchy. If not, or the operation fails, the refs are > dropped. This scatters module ref handling across multiple functions > making it difficult to track. It also make the function nasty to use > for dynamic subsystem binding which is necessary for the planned > unified hierarchy. > > There's nothing which requires the subsystem modules to be pinned > between parse_cgroupfs_options() and rebind_subsystems() in both mount > and remount paths. parse_cgroupfs_options() can just parse and > rebind_subsystems() can handle pinning the subsystems that it wants to > bind, which is a natural part of its task - binding - anyway. > > Move module ref handling into rebind_subsystems() which makes the code > a lot simpler - modules are gotten iff it's gonna be bound and put iff > unbound or binding fails. > > v2: Li pointed out that if a controller module is unloaded between > parsing and binding, rebind_subsystems() won't notice the missing > controller as it only iterates through existing controllers. Fix > it by updating rebind_subsystems() to compare @added_mask to > @pinned and fail with -ENOENT if they don't match. > > Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> > Cc: Li Zefan <lizefan@xxxxxxxxxx> Acked-by: Li Zefan <lizefan@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
