[iproute] rdma broken on 32 bit

[iproute] rdma broken on 32 bit

[Stephen Hemminger]

It appears that RDMA is broken on 32 bit platforms.
Sure you don't run on 32bit, but iproute2 needs to build everywhere.

The issue is that  you are assuming a C enum can hold 64 bits.
The standard says enum only has to hold "int" values.
So it breaks on 32bit.

The issue is deeper than just a trivial fix. Please either change iproute
config script to not build RDMA if sizeof(enum) < 64 or fix the code to
use a safe value like uint64_t.

rdma
    CC       rdma.o
    CC       utils.o
    CC       dev.o
    CC       link.o
In file included from rdma.h:26:0,
                 from dev.c:12:
dev.c: In function ‘dev_caps_to_str’:
../include/utils.h:269:38: warning: left shift count >= width of type [-Wshift-count-overflow]
 #define BIT(nr)                 (1UL << (nr))
                                      ^
rdma.h:32:61: note: in expansion of macro ‘BIT’
 #define RDMA_BITMAP_ENUM(name, bit_no) RDMA_BITMAP_##name = BIT(bit_no),
                                                             ^~~
If you wade through the macro swamp:
dev.c
#define RDMA_DEV_FLAGS(x) \

	x(SG_GAPS_REG, 32) \

	enum { RDMA_DEV_FLAGS(RDMA_BITMAP_ENUM) };

Expands to:
	enum {
		RDMA_BITMAP_SG_GAPS_REG = (1UL << (32)),
	};
		

Re: [iproute] rdma broken on 32 bit

[Leon Romanovsky]

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On Mon, Dec 10, 2018 at 02:10:20PM -0800, Stephen Hemminger wrote:
> It appears that RDMA is broken on 32 bit platforms.
> Sure you don't run on 32bit, but iproute2 needs to build everywhere.
>
> The issue is that  you are assuming a C enum can hold 64 bits.
> The standard says enum only has to hold "int" values.
> So it breaks on 32bit.
>
> The issue is deeper than just a trivial fix. Please either change iproute
> config script to not build RDMA if sizeof(enum) < 64 or fix the code to
> use a safe value like uint64_t.
>
> rdma
>     CC       rdma.o
>     CC       utils.o
>     CC       dev.o
>     CC       link.o
> In file included from rdma.h:26:0,
>                  from dev.c:12:
> dev.c: In function ‘dev_caps_to_str’:
> ../include/utils.h:269:38: warning: left shift count >= width of type [-Wshift-count-overflow]
>  #define BIT(nr)                 (1UL << (nr))
>                                       ^
> rdma.h:32:61: note: in expansion of macro ‘BIT’
>  #define RDMA_BITMAP_ENUM(name, bit_no) RDMA_BITMAP_##name = BIT(bit_no),
>                                                              ^~~
> If you wade through the macro swamp:
> dev.c
> #define RDMA_DEV_FLAGS(x) \
>
> 	x(SG_GAPS_REG, 32) \
>
> 	enum { RDMA_DEV_FLAGS(RDMA_BITMAP_ENUM) };
>
> Expands to:
> 	enum {
> 		RDMA_BITMAP_SG_GAPS_REG = (1UL << (32)),
> 	};
>

Thanks for the report, I reproduced and will do my best to send patches tomorrow.

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Re: [iproute] rdma broken on 32 bit

[Stephen Hemminger]

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On Tue, 11 Dec 2018 17:33:19 +0000
Leon Romanovsky <leonro@mellanox.com> wrote:

> On Mon, Dec 10, 2018 at 02:10:20PM -0800, Stephen Hemminger wrote:
> > It appears that RDMA is broken on 32 bit platforms.
> > Sure you don't run on 32bit, but iproute2 needs to build everywhere.
> >
> > The issue is that  you are assuming a C enum can hold 64 bits.
> > The standard says enum only has to hold "int" values.
> > So it breaks on 32bit.
> >
> > The issue is deeper than just a trivial fix. Please either change iproute
> > config script to not build RDMA if sizeof(enum) < 64 or fix the code to
> > use a safe value like uint64_t.
> >
> > rdma
> >     CC       rdma.o
> >     CC       utils.o
> >     CC       dev.o
> >     CC       link.o
> > In file included from rdma.h:26:0,
> >                  from dev.c:12:
> > dev.c: In function ‘dev_caps_to_str’:
> > ../include/utils.h:269:38: warning: left shift count >= width of type [-Wshift-count-overflow]
> >  #define BIT(nr)                 (1UL << (nr))
> >                                       ^
> > rdma.h:32:61: note: in expansion of macro ‘BIT’
> >  #define RDMA_BITMAP_ENUM(name, bit_no) RDMA_BITMAP_##name = BIT(bit_no),
> >                                                              ^~~
> > If you wade through the macro swamp:
> > dev.c
> > #define RDMA_DEV_FLAGS(x) \
> >
> > 	x(SG_GAPS_REG, 32) \
> >
> > 	enum { RDMA_DEV_FLAGS(RDMA_BITMAP_ENUM) };
> >
> > Expands to:
> > 	enum {
> > 		RDMA_BITMAP_SG_GAPS_REG = (1UL << (32)),
> > 	};
> >  
> 
> Thanks for the report, I reproduced and will do my best to send patches tomorrow.

Thanks for fixing it so fast. Applied your fix

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