diff mbox series

[net-next,v3,02/12] net: sched: flower: refactor fl_change

Message ID 20190321131744.19224-3-vladbu@mellanox.com
State Accepted
Delegated to: David Miller
Headers show
Series Refactor flower classifier to remove dependency on rtnl lock | expand

Commit Message

Vlad Buslov March 21, 2019, 1:17 p.m. UTC 
As a preparation for using classifier spinlock instead of relying on
external rtnl lock, rearrange code in fl_change. The goal is to group the
code which changes classifier state in single block in order to allow
following commits in this set to protect it from parallel modification with
tp->lock. Data structures that require tp->lock protection are mask
hashtable and filters list, and classifier handle_idr.

fl_hw_replace_filter() is a sleeping function and cannot be called while
holding a spinlock. In order to execute all sequence of changes to shared
classifier data structures atomically, call fl_hw_replace_filter() before
modifying them.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
---
 net/sched/cls_flower.c | 80 ++++++++++++++++++++++--------------------
 1 file changed, 41 insertions(+), 39 deletions(-)

Comments

Jiri Pirko March 21, 2019, 1:53 p.m. UTC | #1 
Thu, Mar 21, 2019 at 02:17:34PM CET, vladbu@mellanox.com wrote:
>As a preparation for using classifier spinlock instead of relying on
>external rtnl lock, rearrange code in fl_change. The goal is to group the
>code which changes classifier state in single block in order to allow
>following commits in this set to protect it from parallel modification with
>tp->lock. Data structures that require tp->lock protection are mask
>hashtable and filters list, and classifier handle_idr.
>
>fl_hw_replace_filter() is a sleeping function and cannot be called while
>holding a spinlock. In order to execute all sequence of changes to shared
>classifier data structures atomically, call fl_hw_replace_filter() before
>modifying them.
>
>Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
>Reviewed-by: Stefano Brivio <sbrivio@redhat.com>

Acked-by: Jiri Pirko <jiri@mellanox.com>
diff mbox series

Patch

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index dcf3aee5697e..d36ceb5001f9 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1376,73 +1376,75 @@  static int fl_change(struct net *net, struct sk_buff *in_skb,
 	if (err)
 		goto errout;
 
-	if (!handle) {
-		handle = 1;
-		err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
-				    INT_MAX, GFP_KERNEL);
-	} else if (!fold) {
-		/* user specifies a handle and it doesn't exist */
-		err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
-				    handle, GFP_KERNEL);
-	}
-	if (err)
-		goto errout_mask;
-	fnew->handle = handle;
-
-	if (!fold && __fl_lookup(fnew->mask, &fnew->mkey)) {
-		err = -EEXIST;
-		goto errout_idr;
-	}
-
-	err = rhashtable_insert_fast(&fnew->mask->ht, &fnew->ht_node,
-				     fnew->mask->filter_ht_params);
-	if (err)
-		goto errout_idr;
-
 	if (!tc_skip_hw(fnew->flags)) {
 		err = fl_hw_replace_filter(tp, fnew, extack);
 		if (err)
-			goto errout_mask_ht;
+			goto errout_mask;
 	}
 
 	if (!tc_in_hw(fnew->flags))
 		fnew->flags |= TCA_CLS_FLAGS_NOT_IN_HW;
 
 	if (fold) {
+		fnew->handle = handle;
+
+		err = rhashtable_insert_fast(&fnew->mask->ht, &fnew->ht_node,
+					     fnew->mask->filter_ht_params);
+		if (err)
+			goto errout_hw;
+
 		rhashtable_remove_fast(&fold->mask->ht,
 				       &fold->ht_node,
 				       fold->mask->filter_ht_params);
-		if (!tc_skip_hw(fold->flags))
-			fl_hw_destroy_filter(tp, fold, NULL);
-	}
-
-	*arg = fnew;
-
-	if (fold) {
 		idr_replace(&head->handle_idr, fnew, fnew->handle);
 		list_replace_rcu(&fold->list, &fnew->list);
+
+		if (!tc_skip_hw(fold->flags))
+			fl_hw_destroy_filter(tp, fold, NULL);
 		tcf_unbind_filter(tp, &fold->res);
 		tcf_exts_get_net(&fold->exts);
 		tcf_queue_work(&fold->rwork, fl_destroy_filter_work);
 	} else {
+		if (__fl_lookup(fnew->mask, &fnew->mkey)) {
+			err = -EEXIST;
+			goto errout_hw;
+		}
+
+		if (handle) {
+			/* user specifies a handle and it doesn't exist */
+			err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
+					    handle, GFP_ATOMIC);
+		} else {
+			handle = 1;
+			err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
+					    INT_MAX, GFP_ATOMIC);
+		}
+		if (err)
+			goto errout_hw;
+
+		fnew->handle = handle;
+
+		err = rhashtable_insert_fast(&fnew->mask->ht, &fnew->ht_node,
+					     fnew->mask->filter_ht_params);
+		if (err)
+			goto errout_idr;
+
 		list_add_tail_rcu(&fnew->list, &fnew->mask->filters);
 	}
 
+	*arg = fnew;
+
 	kfree(tb);
 	kfree(mask);
 	return 0;
 
-errout_mask_ht:
-	rhashtable_remove_fast(&fnew->mask->ht, &fnew->ht_node,
-			       fnew->mask->filter_ht_params);
-
 errout_idr:
-	if (!fold)
-		idr_remove(&head->handle_idr, fnew->handle);
-
+	idr_remove(&head->handle_idr, fnew->handle);
+errout_hw:
+	if (!tc_skip_hw(fnew->flags))
+		fl_hw_destroy_filter(tp, fnew, NULL);
 errout_mask:
 	fl_mask_put(head, fnew->mask, false);
-
 errout:
 	tcf_exts_destroy(&fnew->exts);
 	kfree(fnew);