Re: [PATCH v4 iproute2 2/7] rdma: Add dev object

[Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

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On Tue, Aug 15, 2017 at 05:00:54PM +0000, David Laight wrote:
> From: Leon Romanovsky
> > Sent: 15 August 2017 17:47
> > On Tue, Aug 15, 2017 at 04:23:11PM +0000, David Laight wrote:
> > > From: Stephen Hemminger
> > > > Sent: 15 August 2017 17:12
> > > > On Tue, 15 Aug 2017 16:00:15 +0300
> > > > Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> wrote:
> > > >
> > > > > +
> > > > > +static const char *dev_caps_to_str(uint32_t idx)
> > > > > +{
> > > > > +	uint64_t cap = 1 << idx;
> > > > > +
> > > > > +	switch (cap) {
> > > > > +	case RDMA_DEV_RESIZE_MAX_WR: return "RESIZE_MAX_WR";
> > > > > +	case RDMA_DEV_BAD_PKEY_CNTR: return "BAD_PKEY_CNTR";
> > > ...
> > > > > +	case RDMA_DEV_RAW_SCATTER_FCS: return "RAW_SCATTER_FCS";
> > > > > +	case RDMA_DEV_RDMA_NETDEV_OPA_VNIC: return "RDMA_NETDEV_OPA_VNIC";
> > > > > +	default: return "UNKNOWN";
> > > > > +	}
> > > >
> > > > Could this be a table in future versions?
> > >
> > > Potentially you could define the constants using some pre-processor
> > > 'magic' that would create the table for you.
> > > Something like (but not compiled):
> > >
> > > #define RDMA_DEV_FLAGS(x) \
> > > 	x(RESIZE_MAX_WR, 0) \
> > > 	x(BAD_PKEY_CNTR, 1) \
> > > (continue for all the bits)
> > >
> > > #define RDMA_DEV_ENUM(name, bit_no) RDMA_DEV_##name = BIT(bit_no),
> > > enum {RDMA_DEV_FLAGS(RDMA_DEV_ENUM)};
> > > #undef RDMA_DEV_ENUM
> > >
> > > #define RDMA_DEV_NAMES(name, bit_no) [bit_no] = #name,
> > > static const char rdma_dev_names[] = {RDMA_DEV_FLAGS(RDMA_DEV_NAMES)};
> I missed the #undef
> > >
> >
> > David,
> >
> > How should I handle "uknown" fields without names?
>
> The function that accesses rdma_dev_names[] checks ARRAY_SIZE()
> and for a NULL pointer.

Thanks, I'll definitely try it.

>
> WRT the other comment, the spare pointers consume far less space than
> the code for your switch statement.

I don't think that space is matter for this tool.

>
> 	David
>

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