• Tejun Heo's avatar
    percpu-refcount: require percpu_ref to be exited explicitly · 9a1049da
    Tejun Heo authored
    Currently, a percpu_ref undoes percpu_ref_init() automatically by
    freeing the allocated percpu area when the percpu_ref is killed.
    While seemingly convenient, this has the following niggles.
    
    * It's impossible to re-init a released reference counter without
      going through re-allocation.
    
    * In the similar vein, it's impossible to initialize a percpu_ref
      count with static percpu variables.
    
    * We need and have an explicit destructor anyway for failure paths -
      percpu_ref_cancel_init().
    
    This patch removes the automatic percpu counter freeing in
    percpu_ref_kill_rcu() and repurposes percpu_ref_cancel_init() into a
    generic destructor now named percpu_ref_exit().  percpu_ref_destroy()
    is considered but it gets confusing with percpu_ref_kill() while
    "exit" clearly indicates that it's the counterpart of
    percpu_ref_init().
    
    All percpu_ref_cancel_init() users are updated to invoke
    percpu_ref_exit() instead and explicit percpu_ref_exit() calls are
    added to the destruction path of all percpu_ref users.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Acked-by: default avatarBenjamin LaHaise <bcrl@kvack.org>
    Cc: Kent Overstreet <kmo@daterainc.com>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Cc: Benjamin LaHaise <bcrl@kvack.org>
    Cc: Nicholas A. Bellinger <nab@linux-iscsi.org>
    Cc: Li Zefan <lizefan@huawei.com>
    9a1049da
cgroup.c 144 KB