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authorSergey Ryazanov <ryazanov.s.a@gmail.com>2021-06-22 01:50:57 +0300
committerDavid S. Miller <davem@davemloft.net>2021-06-22 20:01:16 +0300
commit9f0248ea476ee59d336d7c8bf1a5d0919d93d030 (patch)
treea012e1c1b0cd41284f25628478910cf3babdef03
parent322a0ba99c50d6abadeda709f0552eb8dac6668c (diff)
downloadlinux-9f0248ea476ee59d336d7c8bf1a5d0919d93d030.tar.xz
wwan: core: no more hold netdev ops owning module
The WWAN netdev ops owner holding was used to protect from the unexpected memory disappear. This approach causes a dependency cycle (driver -> core -> driver) and effectively prevents a WWAN driver unloading. E.g. WWAN hwsim could not be unloaded until all simulated devices are removed: ~# modprobe wwan_hwsim devices=2 ~# lsmod | grep wwan wwan_hwsim 16384 2 wwan 20480 1 wwan_hwsim ~# rmmod wwan_hwsim rmmod: ERROR: Module wwan_hwsim is in use ~# echo > /sys/kernel/debug/wwan_hwsim/hwsim0/destroy ~# echo > /sys/kernel/debug/wwan_hwsim/hwsim1/destroy ~# lsmod | grep wwan wwan_hwsim 16384 0 wwan 20480 1 wwan_hwsim ~# rmmod wwan_hwsim For a real device driver this will cause an inability to unload module until a served device is physically detached. Since the last commit we are removing all child netdev(s) when a driver unregister the netdev ops. This allows us to permit the driver unloading, since any sane driver will call ops unregistering on a device deinitialization. So, remove the holding of an ops owner to make it easier to unload a driver module. The owner field has also beed removed from the ops structure as there are no more users of this field. Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com> Reviewed-by: Loic Poulain <loic.poulain@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/mhi/net.c3
-rw-r--r--drivers/net/wwan/wwan_core.c10
-rw-r--r--drivers/net/wwan/wwan_hwsim.c1
-rw-r--r--include/linux/wwan.h2
4 files changed, 1 insertions, 15 deletions
diff --git a/drivers/net/mhi/net.c b/drivers/net/mhi/net.c
index 6aa753387372..ffd1c01b3f35 100644
--- a/drivers/net/mhi/net.c
+++ b/drivers/net/mhi/net.c
@@ -383,7 +383,6 @@ static void mhi_net_dellink(void *ctxt, struct net_device *ndev,
}
static const struct wwan_ops mhi_wwan_ops = {
- .owner = THIS_MODULE,
.priv_size = sizeof(struct mhi_net_dev),
.setup = mhi_net_setup,
.newlink = mhi_net_newlink,
@@ -436,7 +435,7 @@ static void mhi_net_remove(struct mhi_device *mhi_dev)
struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
struct mhi_controller *cntrl = mhi_dev->mhi_cntrl;
- /* rtnetlink takes care of removing remaining links */
+ /* WWAN core takes care of removing remaining links */
wwan_unregister_ops(&cntrl->mhi_dev->dev);
if (create_default_iface)
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index ec6a69b23dd1..b634a0ba1196 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -929,11 +929,6 @@ int wwan_register_ops(struct device *parent, const struct wwan_ops *ops,
return -EBUSY;
}
- if (!try_module_get(ops->owner)) {
- wwan_remove_dev(wwandev);
- return -ENODEV;
- }
-
wwandev->ops = ops;
wwandev->ops_ctxt = ctxt;
@@ -960,7 +955,6 @@ static int wwan_child_dellink(struct device *dev, void *data)
void wwan_unregister_ops(struct device *parent)
{
struct wwan_device *wwandev = wwan_dev_get_by_parent(parent);
- struct module *owner;
LIST_HEAD(kill_list);
if (WARN_ON(IS_ERR(wwandev)))
@@ -976,8 +970,6 @@ void wwan_unregister_ops(struct device *parent)
*/
put_device(&wwandev->dev);
- owner = wwandev->ops->owner; /* Preserve ops owner */
-
rtnl_lock(); /* Prevent concurent netdev(s) creation/destroying */
/* Remove all child netdev(s), using batch removing */
@@ -989,8 +981,6 @@ void wwan_unregister_ops(struct device *parent)
rtnl_unlock();
- module_put(owner);
-
wwandev->ops_ctxt = NULL;
wwan_remove_dev(wwandev);
}
diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c
index c1e850b9c087..a8582a58a385 100644
--- a/drivers/net/wwan/wwan_hwsim.c
+++ b/drivers/net/wwan/wwan_hwsim.c
@@ -94,7 +94,6 @@ static void wwan_hwsim_netdev_setup(struct net_device *ndev)
}
static const struct wwan_ops wwan_hwsim_wwan_rtnl_ops = {
- .owner = THIS_MODULE,
.priv_size = 0, /* No private data */
.setup = wwan_hwsim_netdev_setup,
};
diff --git a/include/linux/wwan.h b/include/linux/wwan.h
index 34222230360c..e1981ea3a2fd 100644
--- a/include/linux/wwan.h
+++ b/include/linux/wwan.h
@@ -128,14 +128,12 @@ void *wwan_port_get_drvdata(struct wwan_port *port);
/**
* struct wwan_ops - WWAN device ops
- * @owner: module owner of the WWAN ops
* @priv_size: size of private netdev data area
* @setup: set up a new netdev
* @newlink: register the new netdev
* @dellink: remove the given netdev
*/
struct wwan_ops {
- struct module *owner;
unsigned int priv_size;
void (*setup)(struct net_device *dev);
int (*newlink)(void *ctxt, struct net_device *dev,