From 143976ce992fcf3bfc0f4d15d5726bb492dcf262 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Thu, 24 Aug 2017 16:51:29 -0700 Subject: net_sched: remove tc class reference counting For TC classes, their ->get() and ->put() are always paired, and the reference counting is completely useless, because: 1) For class modification and dumping paths, we already hold RTNL lock, so all of these ->get(),->change(),->put() are atomic. 2) For filter bindiing/unbinding, we use other reference counter than this one, and they should have RTNL lock too. 3) For ->qlen_notify(), it is special because it is called on ->enqueue() path, but we already hold qdisc tree lock there, and we hold this tree lock when graft or delete the class too, so it should not be gone or changed until we release the tree lock. Therefore, this patch removes ->get() and ->put(), but: 1) Adds a new ->find() to find the pointer to a class by classid, no refcnt. 2) Move the original class destroy upon the last refcnt into ->delete(), right after releasing tree lock. This is fine because the class is already removed from hash when holding the lock. For those who also use ->put() as ->unbind(), just rename them to reflect this change. Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Acked-by: Jiri Pirko Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- net/sched/sch_drr.c | 30 +++++------------------------- 1 file changed, 5 insertions(+), 25 deletions(-) (limited to 'net/sched/sch_drr.c') diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index 1d2f6235dfcf..2d0e8d4bdc29 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -20,7 +20,6 @@ struct drr_class { struct Qdisc_class_common common; - unsigned int refcnt; unsigned int filter_cnt; struct gnet_stats_basic_packed bstats; @@ -111,7 +110,6 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (cl == NULL) return -ENOBUFS; - cl->refcnt = 1; cl->common.classid = classid; cl->quantum = quantum; cl->qdisc = qdisc_create_dflt(sch->dev_queue, @@ -163,32 +161,15 @@ static int drr_delete_class(struct Qdisc *sch, unsigned long arg) drr_purge_queue(cl); qdisc_class_hash_remove(&q->clhash, &cl->common); - BUG_ON(--cl->refcnt == 0); - /* - * This shouldn't happen: we "hold" one cops->get() when called - * from tc_ctl_tclass; the destroy method is done from cops->put(). - */ - sch_tree_unlock(sch); - return 0; -} - -static unsigned long drr_get_class(struct Qdisc *sch, u32 classid) -{ - struct drr_class *cl = drr_find_class(sch, classid); - if (cl != NULL) - cl->refcnt++; - - return (unsigned long)cl; + drr_destroy_class(sch, cl); + return 0; } -static void drr_put_class(struct Qdisc *sch, unsigned long arg) +static unsigned long drr_search_class(struct Qdisc *sch, u32 classid) { - struct drr_class *cl = (struct drr_class *)arg; - - if (--cl->refcnt == 0) - drr_destroy_class(sch, cl); + return (unsigned long)drr_find_class(sch, classid); } static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl) @@ -478,8 +459,7 @@ static void drr_destroy_qdisc(struct Qdisc *sch) static const struct Qdisc_class_ops drr_class_ops = { .change = drr_change_class, .delete = drr_delete_class, - .get = drr_get_class, - .put = drr_put_class, + .find = drr_search_class, .tcf_block = drr_tcf_block, .bind_tcf = drr_bind_tcf, .unbind_tcf = drr_unbind_tcf, -- cgit v1.2.3