| Message ID | 20240311085726.273193-1-shayd@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] devlink: Fix devlink parallel commands processing | expand |
On Mon, 11 Mar 2024 10:57:26 +0200 Shay Drory wrote: > devlinks_xa_for_each_registered_get(net, index, devlink) { > - devl_dev_lock(devlink, dev_lock); > - if (devl_is_registered(devlink) && > - strcmp(devlink->dev->bus->name, busname) == 0 && > + if (strcmp(devlink->dev->bus->name, busname) == 0 && > strcmp(dev_name(devlink->dev), devname) == 0) > - return devlink; > - devl_dev_unlock(devlink, dev_lock); > + goto found; there's no need for a goto here: if (strcmp(devlink->dev->bus->name, busname) == 0 && strcmp(dev_name(devlink->dev), devname) == 0) { devl_dev_lock(devlink, dev_lock); if (devl_is_registered(devlink)) return devlink; devl_dev_unlock(devlink, dev_lock); } simpler, and also no change in behavior (in case some impossible race happens and we have 2 devlinks with the same name, one already unregistered and one registered). > devlink_put(devlink); > } > + return ERR_PTR(-ENODEV); > + > +found: > + devl_dev_lock(devlink, dev_lock); > + if (devl_is_registered(devlink)) > + return devlink; > > + devl_dev_unlock(devlink, dev_lock); > + devlink_put(devlink); > return ERR_PTR(-ENODEV);
diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c index 499885c8b9ca..cffc7274de8c 100644 --- a/net/devlink/netlink.c +++ b/net/devlink/netlink.c @@ -193,15 +193,20 @@ devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs, devname = nla_data(attrs[DEVLINK_ATTR_DEV_NAME]); devlinks_xa_for_each_registered_get(net, index, devlink) { - devl_dev_lock(devlink, dev_lock); - if (devl_is_registered(devlink) && - strcmp(devlink->dev->bus->name, busname) == 0 && + if (strcmp(devlink->dev->bus->name, busname) == 0 && strcmp(dev_name(devlink->dev), devname) == 0) - return devlink; - devl_dev_unlock(devlink, dev_lock); + goto found; devlink_put(devlink); } + return ERR_PTR(-ENODEV); + +found: + devl_dev_lock(devlink, dev_lock); + if (devl_is_registered(devlink)) + return devlink; + devl_dev_unlock(devlink, dev_lock); + devlink_put(devlink); return ERR_PTR(-ENODEV); }
Commit 870c7ad4a52b ("devlink: protect devlink->dev by the instance lock") added devlink instance locking inside a loop that iterates over all the registered devlink instances on the machine in the pre-doit phase. This can lead to serialization of devlink commands over different devlink instances. For example: While the first devlink instance is executing firmware flash, all commands to other devlink instances on the machine are forced to wait until the first devlink finishes. Therefore, in the pre-doit phase, take the devlink instance lock only for the devlink instance the command is targeting. Devlink layer is taking a reference on the devlink instance, ensuring the devlink->dev pointer is valid. This reference taking was introduced by commit a380687200e0 ("devlink: take device reference for devlink object"). Without this commit, it would not be safe to access devlink->dev lockless. Fixes: 870c7ad4a52b ("devlink: protect devlink->dev by the instance lock") Signed-off-by: Shay Drory <shayd@nvidia.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com> --- net/devlink/netlink.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)