On 04-Jan-19 18:35, Jason Gunthorpe wrote: > On Fri, Jan 04, 2019 at 12:31:21PM +0200, Gal Pressman wrote: >> On 04-Jan-19 06:11, Jason Gunthorpe wrote: >>> On Thu, Jan 03, 2019 at 06:32:56PM -0500, Doug Ledford wrote: >>> >>>>> The original point is still un-addressed. We, as a community, have >>>>> identified usnic as a bad idea that does not belong in >>>>> drivers/infiniband. This has been a pretty much universal position of >>>>> everyone who has worked on the core RDMA stack. >>>> >>>> I'll generally agree with this. It turns out usnic is not so much about >>>> access to a shared device with PD, QP, CQ, MR and AH support, but an >>>> SRIOV network device attached to a process with minimal (but sufficient >>>> I think) security measures to at least make sure that process can't >>>> listen in on other traffic. From there, it's just UDP on a private >>>> network adapter. >>> >>> EFA looks the same to me, except instead of UDP it is doing a bit >>> more, but it still just datagram processing. There are no verbs here >>> other than SEND and RECV. There is no RMA.. >>> >>> The functions usnic and EFA stub to EOPNOTSUPP/null look super similar >>> to me. >> >> The stubs are there because of IB_MANDATORY_FUNC. > > Yes, because those functions are *MANDATORY* to be an actual verbs > device :) > > That is another thing that should be revised for these no-kverbs > things, I don't want to see stubs.. > > In fact seeing null in any mandatory function pointers is a good way > to trigger the 'clients cannot be attached' behavior in your earlier > RFC patch. > >>> I've never used usnic, is this true? It sure looks like it can >>> allocate ucontexts dynamically?? I think that is what the vnic stuff >>> is for?? Maybe the ucontext limit is pretty small, but there sure is >>> alot of code here if the limit is just 1.. We also don't know the EFA >>> ucontext limit ... >> >> There is no ucontext limit. > > Oh? EFA is sharing BAR pages between user processes? You have a > security proof that is OK? I guess we're talking about PDs? There's a PD limit (currently 128, depends on the device) which limits the number of processes. There is no sharing of BAR pages between user processes.
