devlink: change per-devlink netdev notifier to static one

The commit 565b4824c39f ("devlink: change port event netdev notifier
from per-net to global") changed original per-net notifier to be
per-devlink instance. That fixed the issue of non-receiving events
of netdev uninit if that moved to a different namespace.
That worked fine in -net tree.

However, later on when commit ee75f1fc44dd ("net/mlx5e: Create
separate devlink instance for ethernet auxiliary device") and
commit 72ed5d5624af ("net/mlx5: Suspend auxiliary devices only in
case of PCI device suspend") were merged, a deadlock was introduced
when removing a namespace with devlink instance with another nested
instance.

Here there is the bad flow example resulting in deadlock with mlx5:
net_cleanup_work -> cleanup_net (takes down_read(&pernet_ops_rwsem) ->
devlink_pernet_pre_exit() -> devlink_reload() ->
mlx5_devlink_reload_down() -> mlx5_unload_one_devl_locked() ->
mlx5_detach_device() -> del_adev() -> mlx5e_remove() ->
mlx5e_destroy_devlink() -> devlink_free() ->
unregister_netdevice_notifier() (takes down_write(&pernet_ops_rwsem)

Steps to reproduce:
$ modprobe mlx5_core
$ ip netns add ns1
$ devlink dev reload pci/0000:08:00.0 netns ns1
$ ip netns del ns1

Resolve this by converting the notifier from per-devlink instance to
a static one registered during init phase and leaving it registered
forever. Use this notifier for all devlink port instances created
later on.

Note what a tree needs this fix only in case all of the cited fixes
commits are present.

Reported-by: Moshe Shemesh <moshe@nvidia.com>
Fixes: 565b4824c39f ("devlink: change port event netdev notifier from per-net to global")
Fixes: ee75f1fc44dd ("net/mlx5e: Create separate devlink instance for ethernet auxiliary device")
Fixes: 72ed5d5624af ("net/mlx5: Suspend auxiliary devices only in case of PCI device suspend")
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230510144621.932017-1-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/devlink/core.c b/net/devlink/core.c
index 777b091..0e58eee 100644 (file)
--- a/net/devlink/core.c
+++ b/net/devlink/core.c
@@ -204,11 +204,6 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
        if (ret < 0)
                goto err_xa_alloc;
 
-       devlink->netdevice_nb.notifier_call = devlink_port_netdevice_event;
-       ret = register_netdevice_notifier(&devlink->netdevice_nb);
-       if (ret)
-               goto err_register_netdevice_notifier;
-
        devlink->dev = dev;
        devlink->ops = ops;
        xa_init_flags(&devlink->ports, XA_FLAGS_ALLOC);
@@ -233,8 +228,6 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
 
        return devlink;
 
-err_register_netdevice_notifier:
-       xa_erase(&devlinks, devlink->index);
 err_xa_alloc:
        kfree(devlink);
        return NULL;
@@ -266,8 +259,6 @@ void devlink_free(struct devlink *devlink)
        xa_destroy(&devlink->params);
        xa_destroy(&devlink->ports);
 
-       WARN_ON_ONCE(unregister_netdevice_notifier(&devlink->netdevice_nb));
-
        xa_erase(&devlinks, devlink->index);
 
        devlink_put(devlink);
@@ -303,6 +294,10 @@ static struct pernet_operations devlink_pernet_ops __net_initdata = {
        .pre_exit = devlink_pernet_pre_exit,
 };
 
+static struct notifier_block devlink_port_netdevice_nb __net_initdata = {
+       .notifier_call = devlink_port_netdevice_event,
+};
+
 static int __init devlink_init(void)
 {
        int err;
@@ -311,6 +306,9 @@ static int __init devlink_init(void)
        if (err)
                goto out;
        err = register_pernet_subsys(&devlink_pernet_ops);
+       if (err)
+               goto out;
+       err = register_netdevice_notifier(&devlink_port_netdevice_nb);
 
 out:
        WARN_ON(err);

diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
index e133f42..62921b2 100644 (file)
--- a/net/devlink/devl_internal.h
+++ b/net/devlink/devl_internal.h
@@ -50,7 +50,6 @@ struct devlink {
        u8 reload_failed:1;
        refcount_t refcount;
        struct rcu_work rwork;
-       struct notifier_block netdevice_nb;
        char priv[] __aligned(NETDEV_ALIGN);
 };
 

diff --git a/net/devlink/leftover.c b/net/devlink/leftover.c
index dffca2f..cd02549 100644 (file)
--- a/net/devlink/leftover.c
+++ b/net/devlink/leftover.c
@@ -7073,10 +7073,9 @@ int devlink_port_netdevice_event(struct notifier_block *nb,
        struct devlink_port *devlink_port = netdev->devlink_port;
        struct devlink *devlink;
 
-       devlink = container_of(nb, struct devlink, netdevice_nb);
-
-       if (!devlink_port || devlink_port->devlink != devlink)
+       if (!devlink_port)
                return NOTIFY_OK;
+       devlink = devlink_port->devlink;
 
        switch (event) {
        case NETDEV_POST_INIT: