On Sun, Nov 18, 2018 at 04:29:32PM +0200, Leon Romanovsky wrote: > Hi, > > I want to clarify why IB device rename functionality didn't change > debugfs and would like to ask what to do next. > > In drivers/infiniband/hw/*, we have 6 devices which are calling > to debugfs_create_dir() in order to create debugfs root. > > The output is located in /sys/kernel/debug/. > > Such folders are created during driver module load and some of the drivers > creates subfolders for every device initialized, during device probe. > > 1. PCI-based connection > MLX5 and cxgb4 drivers separate the different device by their PCIs. > [leonro@server ~]$ sudo ls /sys/kernel/debug/mlx5/ > 0000:00:0c.0 > > 2. Based on IB device name > HFI1, ocrdma and qib create subfolders with device index embedded in it, > like hfi1_0,...,hfi1_N > > 3. No-separation between devices > USNIC like this. > > So device rename works seamlessly for type #1 and #3. Wile for type #2, > the debugfs entries don't change. > > Right now, I see three options: > 1. Do nothing. I don't think this is an option. If we don't also rename debugfs entries then debugfs entry add will fail during hotplug as the names will be in use. The name assigner chooses the lowest number, so, ie, if it plug in hfi0, and rename it to rdma0 then the next plugin will be hfi0 and the debugfs will fail. Presumably the driver will then fail to load. Since this is basically a race condition with userspace it has to be fixed. Jason
