Hi Dennis, > -----Original Message----- > From: linux-rdma-owner@xxxxxxxxxxxxxxx <linux-rdma- > owner@xxxxxxxxxxxxxxx> On Behalf Of Dennis Dalessandro > Sent: Sunday, November 18, 2018 9:56 PM > To: Leon Romanovsky <leon@xxxxxxxxxx>; Jason Gunthorpe > <jgg@xxxxxxxxxxxx>; Doug Ledford <dledford@xxxxxxxxxx>; Mike > Marciniszyn <mike.marciniszyn@xxxxxxxxx>; Selvin Xavier > <selvin.xavier@xxxxxxxxxxxx>; Devesh Sharma > <devesh.sharma@xxxxxxxxxxxx> > Cc: RDMA mailing list <linux-rdma@xxxxxxxxxxxxxxx> > Subject: Re: Rename of debugfs entries > > On 11/18/2018 9:29 AM, 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. > > 2. Convert type #2 drivers to be type #1. > > 3. Add callback/extra implementation in IB/core to support one live > > driver (hfi1) and two frozen ones. > > It's certainly not accurate to call qib frozen. We may not plan on any new > features but we do intend to keep it live and provide fixes should the need > arise. > > I think the type #2 is much more user friendly than putting in the PCI-ID so > why not convert type #1 to be type #2? > > Now that being said I would imagine we could go with either approach and > leave it up to the administrator to create a udev rule or something and make > symlinks to keep existing tools compatible. So I don't think we need to > support both. The question is which is better #1 or #2? > I think #1 is better because (a) pci naming doesn't change with device renaming. (b) In case of mlx5, debugfs is shared between NIC mlx5_core and mlx5_ib driver. So doing #2 continue to suffer with nic device naming. Also when debugfs is created in mlx5_core netdev is not even registered I think. So stable name doesn't exist for EQs, CQs etc debugfs entry.
