On Tue, Jul 04, 2023 at 04:38:41PM +0300, Leon Romanovsky wrote:
> On Thu, Jun 29, 2023 at 09:07:37AM +0300, Dan Carpenter wrote:
> > This code is trying to ensure that only the flags specified in the list
> > are allowed. The problem is that ucmd->rx_hash_fields_mask is a u64 and
> > the flags are an enum which is treated as a u32 in this context. That
> > means the test doesn't check whether the highest 32 bits are zero.
> >
> > Fixes: 4d02ebd9bbbd ("IB/mlx4: Fix RSS hash fields restrictions")
> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > ---
> > The MLX4_IB_RX_HASH_INNER value is declared as
> > "MLX4_IB_RX_HASH_INNER = 1ULL << 31," which suggests that it
> > should be type ULL but that doesn't work. It will still be basically a
> > u32. (Enum types are weird).
>
> Can you please elaborate more why enum left to be int? It is surprise to me.
Enum types are not defined very strictly in C so it's up to the
compiler.
Clang, GCC and Sparse implement them in the same way. They default
to u32 unless the values can't fit, then they become whatever type fits.
So if you have a negative, it becomes an int or a big value changes the
type to unsigned long.
Since 1ULL < 31 fits in u32 the type is just u32.
regards,
dan carpenter
#include <stdio.h>
enum example_one {
VAL = 1ULL << 31,
};
enum example_two {
NEGATIVE = -2,
};
enum example_three {
BIG = 1ULL << 32,
};
int main(void)
{
enum example_one one = -1;
enum example_two two = -1;
enum example_three three = -1;
printf("%lu\n", sizeof(enum example_one));
if (one > 0)
printf("one unsigned\n");
if (two < 0)
printf("two signed\n");
printf("%lu\n", sizeof(enum example_three));
if (three > 0)
printf("three unsigned\n");
return 0;
}
