Re: [PATCH v1 iproute2-next 2/3] rdma: print driver resource attributes

[Leon Romanovsky <leon@kernel.org>]

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On Mon, May 14, 2018 at 05:04:26PM -0500, Steve Wise wrote:
>
>
> On 5/14/2018 3:41 PM, Jason Gunthorpe wrote:
> > On Mon, May 07, 2018 at 08:53:16AM -0700, Steve Wise wrote:
> >> This enhancement allows printing rdma device-specific state, if provided
> >> by the kernel.  This is done in a generic manner, so rdma tool doesn't
> >> need to know about the details of every type of rdma device.
> >>
> >> Driver attributes for a rdma resource are in the form of <key,
> >> [print_type], value> tuples, where the key is a string and the value can
> >> be any supported driver attribute.  The print_type attribute, if present,
> >> provides a print format to use vs the standard print format for the type.
> >> For example, the default print type for a PROVIDER_S32 value is "%d ",
> >> but "0x%x " if the print_type of PRINT_TYPE_HEX is included inthe tuple.
> >>
> >> Driver resources are only printed when the -dd flag is present.
> >> If -p is present, then the output is formatted to not exceed 80 columns,
> >> otherwise it is printed as a single row to be grep/awk friendly.
> >>
> >> Example output:
> >>
> >> # rdma resource show qp lqpn 1028 -dd -p
> >> link cxgb4_0/- lqpn 1028 rqpn 0 type RC state RTS rq-psn 0 sq-psn 0 path-mig-state MIGRATED pid 0 comm [nvme_rdma]
> >>     sqid 1028 flushed 0 memsize 123968 cidx 85 pidx 85 wq_pidx 106 flush_cidx 85 in_use 0
> >>     size 386 flags 0x0 rqid 1029 memsize 16768 cidx 43 pidx 41 wq_pidx 171 msn 44 rqt_hwaddr 0x2a8a5d00
> >>     rqt_size 256 in_use 128 size 130 idx 43 wr_id 0xffff881057c03408 idx 40 wr_id 0xffff881057c033f0
> > Hey some of these look like kernel pointers.. That is a no-no.. What
> > is up there?
>
> Nothing is defined as a kernel pointer.  But wr_id is often a pointer to
> the kernel rdma application's context...
>
> > The wr_id often contains a pointer, right? So we cannot just pass it
> > to user space..
>
> Hmm.  It is useful for debugging kernel rdma applications.  Perhaps
> these attrs can be only be sent up by the kernel if the capabilities
> allow.  But previous review comments of the kernel series, which is now
> merged, forced me to remove passing the capabilities information to the
> driver resource fill functions. 
>
> So what's the right way to do this?

The reviewer asked do not pass to drivers whole CAP_.. bits, because
they anyway don't need such granularity.

>
> Steve.
>
>

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