phy_init() and phy_exit() will have to do more stuff under rtnl_lock()
in a future change. Since rtnl_unlock() -> netdev_run_todo() does a lot
of stuff under the hood, it's a pity to lock and unlock the rtnetlink
mutex twice in a row.
Change the calling convention such that the only caller of
ethtool_set_ethtool_phy_ops(), phy_device.c, provides a context where
the rtnl_mutex is already acquired.
Note that phy_exit() wasn't performing the opposite teardown of
phy_init(). Reverse mdio_bus_init() with ethtool_set_ethtool_phy_ops(),
so that this is now the case.
Signed-off-by: Vladimir Oltean <[email protected]>
---
Changes in v8:
- Patch is new
drivers/net/phy/phy_device.c | 8 +++++++-
net/ethtool/common.c | 3 +--
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 0c2014accba7..ab53d10f1844 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -30,6 +30,7 @@
#include <linux/phy_led_triggers.h>
#include <linux/pse-pd/pse.h>
#include <linux/property.h>
+#include <linux/rtnetlink.h>
#include <linux/sfp.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
@@ -3451,11 +3452,14 @@ static int __init phy_init(void)
{
int rc;
+ rtnl_lock();
+ ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
+ rtnl_unlock();
+
rc = mdio_bus_init();
if (rc)
return rc;
- ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
features_init();
rc = phy_driver_register(&genphy_c45_driver, THIS_MODULE);
@@ -3477,7 +3481,9 @@ static void __exit phy_exit(void)
phy_driver_unregister(&genphy_c45_driver);
phy_driver_unregister(&genphy_driver);
mdio_bus_exit();
+ rtnl_lock();
ethtool_set_ethtool_phy_ops(NULL);
+ rtnl_unlock();
}
subsys_initcall(phy_init);
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 5fb19050991e..f5598c5f50de 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -665,9 +665,8 @@ const struct ethtool_phy_ops *ethtool_phy_ops;
void ethtool_set_ethtool_phy_ops(const struct ethtool_phy_ops *ops)
{
- rtnl_lock();
+ ASSERT_RTNL();
ethtool_phy_ops = ops;
- rtnl_unlock();
}
EXPORT_SYMBOL_GPL(ethtool_set_ethtool_phy_ops);
--
2.34.1
On Mon, Jul 17, 2023 at 06:27:07PM +0300, Vladimir Oltean wrote:
> phy_init() and phy_exit() will have to do more stuff under rtnl_lock()
> in a future change. Since rtnl_unlock() -> netdev_run_todo() does a lot
> of stuff under the hood, it's a pity to lock and unlock the rtnetlink
> mutex twice in a row.
>
> Change the calling convention such that the only caller of
> ethtool_set_ethtool_phy_ops(), phy_device.c, provides a context where
> the rtnl_mutex is already acquired.
>
> Note that phy_exit() wasn't performing the opposite teardown of
> phy_init(). Reverse mdio_bus_init() with ethtool_set_ethtool_phy_ops(),
> so that this is now the case.
To me, this looks buggy.
> @@ -3451,11 +3452,14 @@ static int __init phy_init(void)
> {
> int rc;
>
> + rtnl_lock();
> + ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
> + rtnl_unlock();
> +
> rc = mdio_bus_init();
> if (rc)
> return rc;
If mdio_bus_init() fails, and phylib is built as a module, then we
leave ethtool_phy_ops pointing into module space that has potentially
been freed or re-used for another module. This error path needs to
properly clean up.
The same is also true for the other failure paths in phy_init() which
already do not cater for their failures leaving a dangling pointer in
ethtool_phy_ops. This should probably be fixed first in a separate
patch for the net tree.
Thanks.
--
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