| Message ID | 20210621225100.21005-8-ryazanov.s.a@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 9f0248ea476ee59d336d7c8bf1a5d0919d93d030 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: WWAN link creation improvements | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 5 maintainers not CCed: subashab@codeaurora.org johannes.berg@intel.com stephan@gerhold.net jiapeng.chong@linux.alibaba.com yangyingliang@huawei.com |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 1 this patch: 1 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 70 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
On Tue, 22 Jun 2021 at 00:51, Sergey Ryazanov <ryazanov.s.a@gmail.com> wrote: > > 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>
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,
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> --- v1 -> v2: * fix a comment before wwan_unregister_ops() in the mhi/net.c drivers/net/mhi/net.c | 3 +-- drivers/net/wwan/wwan_core.c | 10 ---------- drivers/net/wwan/wwan_hwsim.c | 1 - include/linux/wwan.h | 2 -- 4 files changed, 1 insertion(+), 15 deletions(-)