On Thu, 23 May 2019 08:58:03 +0200
Michal Kubecek <mkubecek@xxxxxxx> wrote:
> > diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
> > index abac70ad5c7c..40d4c5f7ea43 100644
> > --- a/drivers/infiniband/hw/mlx5/main.c
> > +++ b/drivers/infiniband/hw/mlx5/main.c
> > @@ -2344,7 +2344,7 @@ static int handle_alloc_dm_sw_icm(struct ib_ucontext *ctx,
> > /* Allocation size must a multiple of the basic block size
> > * and a power of 2.
> > */
> > - act_size = roundup(attr->length, MLX5_SW_ICM_BLOCK_SIZE(dm_db->dev));
> > + act_size = DIV_ROUND_UP_ULL(attr->length, MLX5_SW_ICM_BLOCK_SIZE(dm_db->dev));
> > act_size = roundup_pow_of_two(act_size);
> >
> > dm->size = act_size;
>
> This seems wrong: roundup() rounds up to a multiple of second argument
> but DIV_ROUND_UP_ULL() would divide with rounding up.
Yeah, the macros are a bit confusing. There's unfortunately no
roundup_64() (perhaps we should make one?)
#define roundup(x, y) ( \
{ \
typeof(y) __y = y; \
(((x) + (__y - 1)) / __y) * __y; \
} \
)
#define DIV_ROUND_DOWN_ULL(ll, d) \
({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
#define DIV_ROUND_UP_ULL(ll, d) DIV_ROUND_DOWN_ULL((ll) + (d) - 1, (d))
roundup(a, b) == ((a + b - 1) / b) * b
DIV_ROUND_UP_ULL(a, b) DIV_ROUND_DOWN_ULL(a + b - 1, b)
= (a + b - 1) / b
Hmm, looks like you are right (damn, I thought I did this before
posting the patch, but I must have miscalculated something). It does
look like we are missing a "* b" in there.
I think I'll go and just add a roundup_64()!
Thanks for pointing this out.
-- Steve
