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devlink: always check if the devlink instance is registered

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Always check under the instance lock whether the devlink instance
is still / already registered.

This is a no-op for the most part, as the unregistration path currently
waits for all references. On the init path, however, we may temporarily
open up a race with netdev code, if netdevs are registered before the
devlink instance. This is temporary, the next change fixes it, and this
commit has been split out for the ease of review.

Note that in case of iterating over sub-objects which have their
own lock (regions and line cards) we assume an implicit dependency
between those objects existing and devlink unregistration.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski
2023-01-05 22:33:57 -08:00
committed by David S. Miller
parent 870c7ad4a5
commit ed539ba614
4 changed files with 60 additions and 12 deletions
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19
net/devlink/core.c
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@@ -67,6 +67,15 @@ void devl_unlock(struct devlink *devlink)
}
EXPORT_SYMBOL_GPL(devl_unlock);
/**
* devlink_try_get() - try to obtain a reference on a devlink instance
* @devlink: instance to reference
*
* Obtain a reference on a devlink instance. A reference on a devlink instance
* only implies that it's safe to take the instance lock. It does not imply
* that the instance is registered, use devl_is_registered() after taking
* the instance lock to check registration status.
*/
struct devlink *__must_check devlink_try_get(struct devlink *devlink)
{
if (refcount_inc_not_zero(&devlink->refcount))
@@ -300,10 +309,12 @@ static void __net_exit devlink_pernet_pre_exit(struct net *net)
devlinks_xa_for_each_registered_get(net, index, devlink) {
WARN_ON(!(devlink->features & DEVLINK_F_RELOAD));
devl_lock(devlink);
err = devlink_reload(devlink, &init_net,
DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
DEVLINK_RELOAD_LIMIT_UNSPEC,
&actions_performed, NULL);
err = 0;
if (devl_is_registered(devlink))
err = devlink_reload(devlink, &init_net,
DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
DEVLINK_RELOAD_LIMIT_UNSPEC,
&actions_performed, NULL);
devl_unlock(devlink);
devlink_put(devlink);