The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git after rh7-3.10.0-229.7.2.vz7.6.3 ------> commit 337bb797aa4aa5eca030d634d0a9874290511db5 Author: Vladimir Davydov <vdavy...@parallels.com> Date: Fri Aug 28 14:49:21 2015 +0400
ms/percpu-refcount: Don't use silly cmpxchg() Patchset description: Pulling upstream patches converting css refcnt to percpu_ref. https://jira.sw.ru/browse/PSBM-34174 Kent Overstreet (2): percpu: implement generic percpu refcounting percpu-refcount: Don't use silly cmpxchg() Tejun Heo (9): percpu-refcount: consistently use plain (non-sched) RCU percpu-refcount: cosmetic updates percpu-refcount: add __must_check to percpu_ref_init() and don't use ACCESS_ONCE() in percpu_ref_kill_rcu() percpu-refcount: implement percpu_ref_cancel_init() percpu-refcount: implement percpu_tryget() along with percpu_ref_kill_and_confirm() percpu-refcount: use RCU-sched insted of normal RCU cgroup: reorder the operations in cgroup_destroy_locked() cgroup: split cgroup destruction into two steps cgroup: use percpu refcnt for cgroup_subsys_states === This patch description: From: Kent Overstreet <koverstr...@google.com> The cmpxchg() was just to ensure the debug check didn't race, which was a bit excessive. The caller is supposed to do the appropriate synchronization, which means percpu_ref_kill() can just do a simple store. Signed-off-by: Kent Overstreet <koverstr...@google.com> Signed-off-by: Tejun Heo <t...@kernel.org> (cherry picked from commit c1ae6e9b4db00023b9caed72af49a93abad46452) Signed-off-by: Vladimir Davydov <vdavy...@parallels.com> --- lib/percpu-refcount.c | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index 6f0ffd7..1a17399 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -107,22 +107,11 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) */ void percpu_ref_kill(struct percpu_ref *ref) { - unsigned __percpu *pcpu_count, *old, *new; + WARN_ONCE(REF_STATUS(ref->pcpu_count) == PCPU_REF_DEAD, + "percpu_ref_kill() called more than once!\n"); - pcpu_count = ACCESS_ONCE(ref->pcpu_count); - - do { - if (REF_STATUS(pcpu_count) == PCPU_REF_DEAD) { - WARN(1, "percpu_ref_kill() called more than once!\n"); - return; - } - - old = pcpu_count; - new = (unsigned __percpu *) - (((unsigned long) pcpu_count)|PCPU_REF_DEAD); - - pcpu_count = cmpxchg(&ref->pcpu_count, old, new); - } while (pcpu_count != old); + ref->pcpu_count = (unsigned __percpu *) + (((unsigned long) ref->pcpu_count)|PCPU_REF_DEAD); call_rcu(&ref->rcu, percpu_ref_kill_rcu); } _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel