On Sat, 5 May 2018, Guenter Roeck wrote:
> On Thu, Apr 12, 2018 at 09:49:11AM +0000, Israel Rukshin wrote:
> > Adding the vector offset when calling to mlx5_vector2eqn() is wrong.
> > This is because mlx5_vector2eqn() checks if EQ index is equal to vector number
> > and the fact that the internal completion vectors that mlx5 allocates
> > don't get an EQ index.
> >
> > The second problem here is that using effective_affinity_mask gives the same
> > CPU for different vectors.
> > This leads to unmapped queues when calling it from blk_mq_rdma_map_queues().
> > This doesn't happen when using affinity_hint mask.
> >
> Except that affinity_hint is only defined if SMP is enabled. Without:
>
> include/linux/mlx5/driver.h: In function ‘mlx5_get_vector_affinity_hint’:
> include/linux/mlx5/driver.h:1299:13: error:
> ‘struct irq_desc’ has no member named ‘affinity_hint’
>
> Note that this is the only use of affinity_hint outside kernel/irq.
> Don't other drivers have similar problems ?
Aside of that.
> > static inline const struct cpumask *
> > -mlx5_get_vector_affinity(struct mlx5_core_dev *dev, int vector)
> > +mlx5_get_vector_affinity_hint(struct mlx5_core_dev *dev, int vector)
> > {
> > - const struct cpumask *mask;
> > struct irq_desc *desc;
> > unsigned int irq;
> > int eqn;
> > int err;
> >
> > - err = mlx5_vector2eqn(dev, MLX5_EQ_VEC_COMP_BASE + vector, &eqn, &irq);
> > + err = mlx5_vector2eqn(dev, vector, &eqn, &irq);
> > if (err)
> > return NULL;
> >
> > desc = irq_to_desc(irq);
> > -#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
> > - mask = irq_data_get_effective_affinity_mask(&desc->irq_data);
> > -#else
> > - mask = desc->irq_common_data.affinity;
> > -#endif
> > - return mask;
> > + return desc->affinity_hint;
NAK.
Nothing in regular device drivers is supposed to ever fiddle with struct
irq_desc. The existing code is already a violation of that rule and needs
to be fixed, but not in that way.
The logic here is completely screwed. affinity_hint is set by the driver,
so the driver already knows what it is. If the driver does not set it, then
the thing is NULL.
Thanks,
tglx
