Re: [PATCH rdma-rc v1 2/2] RDMA/cma: Make sure that PSN is not over max allowed

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Mon, Nov 27, 2017 at 11:37:55AM -0700, Jason Gunthorpe wrote:
> On Sun, Nov 26, 2017 at 08:23:54PM +0200, Leon Romanovsky wrote:
> > From: Moni Shoua <monis-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> >
> > This patch limits the initial value for PSN to 24 bits as
> > spec requires.
>
> Since this is for-rc, what is the user visible bug this corrects?
>
> I think it is because the QP setup can fail if reserved bits in the
> CMA message happen to be set?

It won't fail, but will print nasty warning down the road after commit
from Majd "IB/core: Make sure that PSN does not overflow" will be
accepted.

The flow is PSN ->
		seq_num ->
			rq_psn ->
				rdma_init_qp_attr() ->
					ib_modify_qp ->
						ib_modify_qp_with_udata ->

1334                 if (attr_mask & IB_QP_RQ_PSN && attr->rq_psn & ~0xffffff) {
1335                         pr_warn("%s: %s rq_psn overflow, masking to 24 bits\n",
1336                                 __func__, qp->device->name);
1337                         attr->rq_psn &= 0xffffff;
1338                 }

Thanks

>
> Jason

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