linux-kernel - RE: [EXTERNAL] Re: [PATCH rdma-next 1/1] RDMA/mana_ib: indicate that inline data is not supported

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID:
 <PAXPR83MB05599E93C7F584D34D715E8AB4AC2@PAXPR83MB0559.EURPRD83.prod.outlook.com>
Date: Thu, 18 Jul 2024 15:05:59 +0000
From: Konstantin Taranov <kotaranov@...rosoft.com>
To: Jason Gunthorpe <jgg@...dia.com>, Leon Romanovsky <leon@...nel.org>
CC: Konstantin Taranov <kotaranov@...ux.microsoft.com>, Wei Hu
	<weh@...rosoft.com>, "sharmaajay@...rosoft.com" <sharmaajay@...rosoft.com>,
	Long Li <longli@...rosoft.com>, "linux-rdma@...r.kernel.org"
	<linux-rdma@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [EXTERNAL] Re: [PATCH rdma-next 1/1] RDMA/mana_ib: indicate that
 inline data is not supported

> > > > Yes, you are. If user asked for specific functionality
> > > > (max_inline_data != 0) and your device doesn't support it, you should
> return an error.
> > > >
> > > > pvrdma, mlx4 and rvt are not good examples, they should return an
> > > > error as well, but because of being legacy code, we won't change them.
> > > >
> > > > Thanks
> > > >
> > >
> > > I see. So I guess we can return a larger value, but not smaller. Right?
> > > I will send v2 that fails QP creation then.
> > >
> > > In this case, may I submit a patch to rdma-core that queries device
> > > caps before trying to create a qp in rdma_client.c and
> > > rdma_server.c? As that code violates what you described.
> >
> > Let's ask Jason, why is that? Do we allow to ignore max_inline_data?
> >
> > librdmacm/examples/rdma_client.c
> >   63         memset(&attr, 0, sizeof attr);
> >   64         attr.cap.max_send_wr = attr.cap.max_recv_wr = 1;
> >   65         attr.cap.max_send_sge = attr.cap.max_recv_sge = 1;
> >   66         attr.cap.max_inline_data = 16;
> >   67         attr.qp_context = id;
> >   68         attr.sq_sig_all = 1;
> >   69         ret = rdma_create_ep(&id, res, NULL, &attr);
> >   70         // Check to see if we got inline data allowed or not
> >   71         if (attr.cap.max_inline_data >= 16)
> >   72                 send_flags = IBV_SEND_INLINE;
> >   73         else
> >   74                 printf("rdma_client: device doesn't support
> IBV_SEND_INLINE, "
> >   75                        "using sge sends\n");
> 
> I think the idea expressed in this code is that if max_inline_data requested
> too much it would be limited to the device capability.
> 
> ie qp creation should limit the requests values to what the HW can do, similar
> to how entries and other work.
> 
> If the HW has no support it should return - for max_inline_data not an error,
> I guess?

Yes, this code implies that max_inline_data can be ignored at creation, while the manual of ibv_create_qp says:
"The function ibv_create_qp() will update the qp_init_attr->cap struct with the actual QP values of the QP that was created;
the values will be **greater than or equal to** the values requested."

I see two options:
1) Remove code from rdma examples that rely on ignoring max_inline; add a warning to libibverbs when drivers ignore that value.
2) Add to manual that max_inline_data might be ignored by drivers; and allow my current patch that ignores max_inline_data in mana_ib.

I am fine to implement either of two. Please, reply which one you think more correct. I guess option 2 is the safest, but option 1
is more correct in my opinion.

Thanks

> 
> Jason