From: Shay Drory shayd@nvidia.com
[ Upstream commit d7d75124965aee23e5e4421d78376545cf070b0a ]
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 Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/devlink/netlink.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c index 86f12531bf998..0f41fded6a6d7 100644 --- a/net/devlink/netlink.c +++ b/net/devlink/netlink.c @@ -80,12 +80,13 @@ 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 && - strcmp(dev_name(devlink->dev), devname) == 0) - return devlink; - devl_dev_unlock(devlink, dev_lock); + 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); + } devlink_put(devlink); }