Re: [PATCH rdma-next] RDMA/ipoib: Allow user space differentiate between valid dev_port

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On Mon, May 06, 2019 at 04:45:34PM +0300, Gal Pressman wrote:
> On 06-May-19 13:49, Leon Romanovsky wrote:
> > On Mon, May 06, 2019 at 01:35:07PM +0300, Gal Pressman wrote:
> >> On 06-May-19 13:21, Leon Romanovsky wrote:
> >>> From: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> >>>
> >>> Systemd triggers the following warning during IPoIB device load:
> >>>
> >>>  mlx5_core 0000:00:0c.0 ib0: "systemd-udevd" wants to know my dev_id.
> >>>         Should it look at dev_port instead?
> >>>         See Documentation/ABI/testing/sysfs-class-net for more info.
> >>>
> >>> This is caused due to user space attempt to differentiate old systems
> >>> without dev_port and new systems with dev_port. In case dev_port will
> >>> be zero, the systemd will try to read dev_id instead.
> >>>
> >>> There is no need to print a warning in such case, because it is valid
> >>> situation and it is needed to ensure systemd compatibility with old
> >>> kernels.
> >>>
> >>> Link: https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-net_id.c#L358
> >>> Cc: <stable@xxxxxxxxxxxxxxx> # 4.19
> >>> Fixes: f6350da41dc7 ("IB/ipoib: Log sysfs 'dev_id' accesses from userspace")
> >>> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> >>> ---
> >>>  drivers/infiniband/ulp/ipoib/ipoib_main.c | 12 +++++++++++-
> >>>  1 file changed, 11 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> >>> index 48eda16db1a7..34e6495aa8c5 100644
> >>> --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
> >>> +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> >>> @@ -2402,7 +2402,17 @@ static ssize_t dev_id_show(struct device *dev,
> >>>  {
> >>>  	struct net_device *ndev = to_net_dev(dev);
> >>>
> >>> -	if (ndev->dev_id == ndev->dev_port)
> >>> +	/*
> >>> +	 * ndev->dev_port will be equal to 0 in old kernel prior to commit
> >>> +	 * 9b8b2a323008 ("IB/ipoib: Use dev_port to expose network interface port numbers")
> >>> +	 * Zero was chosen as special case for user space applications to fallback
> >>> +	 * and query dev_id to check if it has different value or not.
> >>> +	 *
> >>> +	 * Don't pring warning in such scenario.
> >>
> >> "pring" -> "print".
> >
> > Are you ok with other changes and I can add your ROB tag?
>
> To my understanding, the test should be for just:
> if (ndev->dev_port)
>
> As if dev_port is set then there's no reason to use dev_id, regardless of its value.
> But I'm not really familiar with this flow..

It makes sense, but I'm not certain either.

>
> >>
> >>> +	 *
> >>> +	 * https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-net_id.c#L358
> >>> +	 */
> >>> +	if (ndev->dev_port && ndev->dev_id == ndev->dev_port)
> >>>  		netdev_info_once(ndev,
> >>>  			"\"%s\" wants to know my dev_id. Should it look at dev_port instead? See Documentation/ABI/testing/sysfs-class-net for more info.\n",
> >>>  			current->comm);
> >>>
> >>
>



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