Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754548Ab2KMPbq (ORCPT ); Tue, 13 Nov 2012 10:31:46 -0500 Received: from cantor2.suse.de ([195.135.220.15]:60703 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751627Ab2KMPbV (ORCPT ); Tue, 13 Nov 2012 10:31:21 -0500 From: Michal Hocko To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, KAMEZAWA Hiroyuki , Johannes Weiner , Ying Han , Tejun Heo , Glauber Costa Subject: [RFC 4/5] memcg: clean up mem_cgroup_iter Date: Tue, 13 Nov 2012 16:30:38 +0100 Message-Id: <1352820639-13521-5-git-send-email-mhocko@suse.cz> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1352820639-13521-1-git-send-email-mhocko@suse.cz> References: <1352820639-13521-1-git-send-email-mhocko@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4420 Lines: 167 Get rid of while(!memcg) loop as it is no longer needed because there will always be at least one group that should be visited (root). This patch doesn't add any change to the implementation but it is separate to make a review easier. Signed-off-by: Michal Hocko --- mm/memcontrol.c | 120 +++++++++++++++++++++++++++---------------------------- 1 file changed, 60 insertions(+), 60 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index dd84094..b924f27 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1063,6 +1063,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, struct mem_cgroup *prev, struct mem_cgroup_reclaim_cookie *reclaim) { + struct mem_cgroup_reclaim_iter *uninitialized_var(iter); struct mem_cgroup *memcg = NULL, *last_visited = NULL; @@ -1084,76 +1085,75 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, return root; } - while (!memcg) { - struct mem_cgroup_reclaim_iter *uninitialized_var(iter); - - if (reclaim) { - int nid = zone_to_nid(reclaim->zone); - int zid = zone_idx(reclaim->zone); - struct mem_cgroup_per_zone *mz; - - mz = mem_cgroup_zoneinfo(root, nid, zid); - iter = &mz->reclaim_iter[reclaim->priority]; - spin_lock(&iter->iter_lock); - last_visited = iter->last_visited; - if (prev && reclaim->generation != iter->generation) { - if (last_visited) { - mem_cgroup_put(last_visited); - iter->last_visited = NULL; - } - spin_unlock(&iter->iter_lock); - return NULL; + if (reclaim) { + int nid = zone_to_nid(reclaim->zone); + int zid = zone_idx(reclaim->zone); + struct mem_cgroup_per_zone *mz; + + mz = mem_cgroup_zoneinfo(root, nid, zid); + iter = &mz->reclaim_iter[reclaim->priority]; + spin_lock(&iter->iter_lock); + last_visited = iter->last_visited; + if (prev && reclaim->generation != iter->generation) { + if (last_visited) { + mem_cgroup_put(last_visited); + iter->last_visited = NULL; } + spin_unlock(&iter->iter_lock); + return NULL; } + } - rcu_read_lock(); + rcu_read_lock(); + /* + * Root is not visited by cgroup iterators so it needs a special + * treatment. + */ + if (!last_visited) { + memcg = root; + } else { + struct cgroup *next_cgroup, + *pos = last_visited->css.cgroup; +skip_node: + next_cgroup = cgroup_next_descendant_pre( + pos, + root->css.cgroup); /* - * Root is not visited by cgroup iterators so it needs a special - * treatment. + * Even if we find a group we have to make sure it is + * alive. If not we, should skip the node. */ - if (!last_visited) { - memcg = root; - } else { - struct cgroup *next_cgroup, - *pos = last_visited->css.cgroup; -skip_node: - next_cgroup = cgroup_next_descendant_pre( - pos, - root->css.cgroup); - /* - * Even if we find a group we have to make sure it is - * alive. If not we, should skip the node. - */ - if (next_cgroup) { - struct mem_cgroup *mem = mem_cgroup_from_cont( - next_cgroup); - if (css_tryget(&mem->css)) - memcg = mem; - else { - pos = next_cgroup; - goto skip_node; - } + if (next_cgroup) { + struct mem_cgroup *mem = mem_cgroup_from_cont( + next_cgroup); + if (css_tryget(&mem->css)) + memcg = mem; + else { + pos = next_cgroup; + goto skip_node; } } + } - if (reclaim) { - if (last_visited) - mem_cgroup_put(last_visited); - if (memcg) - mem_cgroup_get(memcg); - iter->last_visited = memcg; - - if (!memcg) - iter->generation++; - else if (!prev && memcg) - reclaim->generation = iter->generation; - spin_unlock(&iter->iter_lock); - } - rcu_read_unlock(); + if (reclaim) { + if (last_visited) + mem_cgroup_put(last_visited); + if (memcg) + mem_cgroup_get(memcg); + iter->last_visited = memcg; - if (prev && !memcg) - return NULL; + if (!memcg) + iter->generation++; + else if (!prev && memcg) + reclaim->generation = iter->generation; + spin_unlock(&iter->iter_lock); } + rcu_read_unlock(); + + /* + * At least root has to be visited + */ + VM_BUG_ON(!prev && !memcg); + return memcg; } -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/