Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1230436

[PATCH 2/9] net: dsa: fix of_mdio_find_bus() device refcount leak

From Russell King <rmk+kernel@arm.linux.org.uk>
Newsgroups linux.kernel
Subject [PATCH 2/9] net: dsa: fix of_mdio_find_bus() device refcount leak
Date 2015-09-22 18:20 +0200
Message-ID <qbysq-219-25@gated-at.bofh.it> (permalink)
References <qbysp-219-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

Current users of of_mdio_find_bus() leak a struct device refcount, as
they fail to clean up the reference obtained inside class_find_device().

Fix the DSA code to properly refcount the returned MDIO bus by:
1. taking a reference on the struct device whenever we assign it to
   pd->chip[x].host_dev.
2. dropping the reference when we overwrite the existing reference.
3. dropping the reference when we free the data structure.
4. dropping the initial reference we obtained after setting up the
   platform data structure, or on failure.

In step 2 above, where we obtain a new MDIO bus, there is no need to
take a reference on it as we would only have to drop it immediately
after assignment again, iow:

	put_device(cd->host_dev);	/* drop original assignment ref */
	cd->host_dev = get_device(&mdio_bus_switch->dev); /* get our ref */
	put_device(&mdio_bus_switch->dev); /* drop of_mdio_find_bus ref */

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 net/dsa/dsa.c | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 76e3800765f8..bf4ba15fb780 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -634,6 +634,10 @@ static void dsa_of_free_platform_data(struct dsa_platform_data *pd)
 			port_index++;
 		}
 		kfree(pd->chip[i].rtable);
+
+		/* Drop our reference to the MDIO bus device */
+		if (pd->chip[i].host_dev)
+			put_device(pd->chip[i].host_dev);
 	}
 	kfree(pd->chip);
 }
@@ -661,16 +665,22 @@ static int dsa_of_probe(struct device *dev)
 		return -EPROBE_DEFER;
 
 	ethernet = of_parse_phandle(np, "dsa,ethernet", 0);
-	if (!ethernet)
-		return -EINVAL;
+	if (!ethernet) {
+		ret = -EINVAL;
+		goto out_put_mdio;
+	}
 
 	ethernet_dev = of_find_net_device_by_node(ethernet);
-	if (!ethernet_dev)
-		return -EPROBE_DEFER;
+	if (!ethernet_dev) {
+		ret = -EPROBE_DEFER;
+		goto out_put_mdio;
+	}
 
 	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
-	if (!pd)
-		return -ENOMEM;
+	if (!pd) {
+		ret = -ENOMEM;
+		goto out_put_mdio;
+	}
 
 	dev->platform_data = pd;
 	pd->of_netdev = ethernet_dev;
@@ -691,7 +701,9 @@ static int dsa_of_probe(struct device *dev)
 		cd = &pd->chip[chip_index];
 
 		cd->of_node = child;
-		cd->host_dev = &mdio_bus->dev;
+
+		/* When assigning the host device, increment its refcount */
+		cd->host_dev = get_device(&mdio_bus->dev);
 
 		sw_addr = of_get_property(child, "reg", NULL);
 		if (!sw_addr)
@@ -711,6 +723,12 @@ static int dsa_of_probe(struct device *dev)
 				ret = -EPROBE_DEFER;
 				goto out_free_chip;
 			}
+
+			/* Drop the mdio_bus device ref, replacing the host
+			 * device with the mdio_bus_switch device, keeping
+			 * the refcount from of_mdio_find_bus() above.
+			 */
+			put_device(cd->host_dev);
 			cd->host_dev = &mdio_bus_switch->dev;
 		}
 
@@ -744,6 +762,10 @@ static int dsa_of_probe(struct device *dev)
 		}
 	}
 
+	/* The individual chips hold their own refcount on the mdio bus,
+	 * so drop ours */
+	put_device(&mdio_bus->dev);
+
 	return 0;
 
 out_free_chip:
@@ -751,6 +773,8 @@ static int dsa_of_probe(struct device *dev)
 out_free:
 	kfree(pd);
 	dev->platform_data = NULL;
+out_put_mdio:
+	put_device(&mdio_bus->dev);
 	return ret;
 }
 
-- 
2.1.0

--
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/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 0/9] Phy, mdiobus, and netdev struct device fixes Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 8/9] phy: add phy_device_remove() Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 5/9] of_mdio: fix MDIO phy device refcounting Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 6/9] net: fix phy refcounting in a bunch of drivers Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 9/9] net: fix net_device refcounting Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 2/9] net: dsa: fix of_mdio_find_bus() device refcount leak Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 3/9] phy: fix mdiobus module safety Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  [PATCH 4/9] phy: add proper phy struct device refcounting Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-22 18:20 +0200
  Re: [PATCH v2 0/9] Phy, mdiobus, and netdev struct device fixes David Miller <davem@davemloft.net> - 2015-09-24 01:30 +0200
    Re: [PATCH v2 0/9] Phy, mdiobus, and netdev struct device fixes Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-09-24 18:10 +0200
  [PATCH RESEND v3 2/9] net: dsa: fix of_mdio_find_bus() device  refcount leak Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 7/9] phy: fixed-phy: properly validate phy in  fixed_phy_update_state() Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 5/9] of_mdio: fix MDIO phy device refcounting Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
    Re: [PATCH RESEND v3 5/9] of_mdio: fix MDIO phy device refcounting Rob Herring <robh@kernel.org> - 2015-09-25 00:30 +0200
  [PATCH RESEND v3 4/9] phy: add proper phy struct device refcounting Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 8/9] phy: add phy_device_remove() Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 1/9] phy: fix of_mdio_find_bus() device refcount  leak Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 6/9] net: fix phy refcounting in a bunch of drivers Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 3/9] phy: fix mdiobus module safety Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:40 +0200
  [PATCH RESEND v3 9/9] net: fix net_device refcounting Russell King <rmk+kernel@arm.linux.org.uk> - 2015-09-24 21:50 +0200

csiph-web