diff mbox series

[net-next,03/11] net: dsa: simplify tree reference counting

Message ID 20171103230530.996-4-vivien.didelot@savoirfairelinux.com
State Accepted, archived
Delegated to: David Miller
Headers show
Series net: dsa: parsing stage | expand

Commit Message

Vivien Didelot Nov. 3, 2017, 11:05 p.m. UTC 
DSA trees have a refcount used to automatically free the dsa_switch_tree
structure once there is no switch devices inside of it.

The refcount is incremented when a switch is added to the tree, and
decremented when it is removed from it.

But because of kref_init, the refcount is also incremented at
initialization, and when looking up the tree from the list for symmetry.

Thus the current code stores the number of switches plus one, and makes
the switch registration more complex.

To simplify the switch registration function, we reset the refcount to
zero after initialization and don't increment it when looking up a tree.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
---
 net/dsa/dsa2.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

Comments

Florian Fainelli Nov. 3, 2017, 11:16 p.m. UTC | #1 
On 11/03/2017 04:05 PM, Vivien Didelot wrote:
> DSA trees have a refcount used to automatically free the dsa_switch_tree
> structure once there is no switch devices inside of it.
> 
> The refcount is incremented when a switch is added to the tree, and
> decremented when it is removed from it.
> 
> But because of kref_init, the refcount is also incremented at
> initialization, and when looking up the tree from the list for symmetry.
> 
> Thus the current code stores the number of switches plus one, and makes
> the switch registration more complex.
> 
> To simplify the switch registration function, we reset the refcount to
> zero after initialization and don't increment it when looking up a tree.
> 
> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
diff mbox series

Patch

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 8b68dc2f5707..d3f1a7607463 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -32,10 +32,9 @@  static struct dsa_switch_tree *dsa_get_dst(unsigned int index)
 	struct dsa_switch_tree *dst;
 
 	list_for_each_entry(dst, &dsa_switch_trees, list)
-		if (dst->index == index) {
-			kref_get(&dst->refcount);
+		if (dst->index == index)
 			return dst;
-		}
+
 	return NULL;
 }
 
@@ -48,11 +47,6 @@  static void dsa_free_dst(struct kref *ref)
 	kfree(dst);
 }
 
-static void dsa_put_dst(struct dsa_switch_tree *dst)
-{
-	kref_put(&dst->refcount, dsa_free_dst);
-}
-
 static struct dsa_switch_tree *dsa_add_dst(unsigned int index)
 {
 	struct dsa_switch_tree *dst;
@@ -63,7 +57,10 @@  static struct dsa_switch_tree *dsa_add_dst(unsigned int index)
 	dst->index = index;
 	INIT_LIST_HEAD(&dst->list);
 	list_add_tail(&dsa_switch_trees, &dst->list);
+
+	/* Initialize the reference counter to the number of switches, not 1 */
 	kref_init(&dst->refcount);
+	refcount_set(&dst->refcount.refcount, 0);
 
 	return dst;
 }
@@ -739,10 +736,8 @@  static int _dsa_register_switch(struct dsa_switch *ds)
 			return -ENOMEM;
 	}
 
-	if (dst->ds[index]) {
-		err = -EBUSY;
-		goto out;
-	}
+	if (dst->ds[index])
+		return -EBUSY;
 
 	ds->dst = dst;
 	ds->index = index;
@@ -758,11 +753,9 @@  static int _dsa_register_switch(struct dsa_switch *ds)
 	if (err < 0)
 		goto out_del_dst;
 
-	if (err == 1) {
-		/* Not all switches registered yet */
-		err = 0;
-		goto out;
-	}
+	/* Not all switches registered yet */
+	if (err == 1)
+		return 0;
 
 	if (dst->applied) {
 		pr_info("DSA: Disjoint trees?\n");
@@ -779,13 +772,10 @@  static int _dsa_register_switch(struct dsa_switch *ds)
 		goto out_del_dst;
 	}
 
-	dsa_put_dst(dst);
 	return 0;
 
 out_del_dst:
 	dsa_dst_del_ds(dst, ds, ds->index);
-out:
-	dsa_put_dst(dst);
 
 	return err;
 }