Re: [dpdk-dev] [21.08 PATCH v1 1/2] power: invert the monitor check

[Alexander Kozyrev <akozyrev@nvidia.com>]

On 11-May-2021 11:39 AM, Anatoly Burakov wrote:
> On 11-May-21 4:31 PM, Anatoly Burakov wrote:
> > Previously, the semantics of power monitor were such that we were
> > checking current value against the expected value, and if they matched,
> > then the sleep was aborted. This is somewhat inflexible, because it only
> > allowed us to check for a specific value.
> >
> > We can reverse the check, and instead have monitor sleep to be aborted
> > if the expected value *doesn't* match what's in memory. This allows us
> > to both implement all currently implemented driver code, as well as
> > support more use cases which don't easily map to previous semantics
> > (such as waiting on writes to AF_XDP counter value).
> >
> > This commit also adjusts all current driver implementations to match the
> > new semantics.
> >
> > Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
> > ---
> 
> <snip>
> 
> > diff --git a/drivers/net/mlx5/mlx5_rx.c b/drivers/net/mlx5/mlx5_rx.c
> > index 6cd71a44eb..3cbbe5bf59 100644
> > --- a/drivers/net/mlx5/mlx5_rx.c
> > +++ b/drivers/net/mlx5/mlx5_rx.c
> > @@ -282,7 +282,7 @@ int mlx5_get_monitor_addr(void *rx_queue, struct
> rte_power_monitor_cond *pmc)
> >   		return -rte_errno;
> >   	}
> >   	pmc->addr = &cqe->op_own;
> > -	pmc->val =  !!idx;
> > +	pmc->val =  !idx;
> >   	pmc->mask = MLX5_CQE_OWNER_MASK;
> >   	pmc->size = sizeof(uint8_t);
> >   	return 0;
> 
> Both previous and current code seem suspicious to me, as no attention is
> paid to endianness of the code. I would appreciate if mlx5 maintainers
> chimed in here :)

It is hard to mess up with endianness when you only have 1 byte :)