On Thu, Dec 10, 2015 at 11:49:40AM -0500, Dalessandro, Dennis wrote: > On Tue, Dec 08, 2015 at 02:52:36PM -0500, ira. weiny wrote: > >On Tue, Dec 08, 2015 at 01:17:48PM -0600, Sean Hefty wrote: > >>> > > +struct ib_pd *rvt_alloc_pd(struct ib_device *ibdev, > >>> > > + struct ib_ucontext *context, > >>> > > + struct ib_udata *udata) > >>> > > +{ > >>> > > + struct rvt_dev_info *dev = ib_to_rvt(ibdev); > >>> > > + struct rvt_pd *pd; > >>> > > + struct ib_pd *ret; > >>> > > + > >>> > > + pd = kmalloc(sizeof(*pd), GFP_KERNEL); > >>> > > + if (!pd) { > >>> > > + ret = ERR_PTR(-ENOMEM); > >>> > > + goto bail; > >>> > > + } > >>> > > + /* > >>> > > + * This is actually totally arbitrary. Some correctness > >>tests > >>> > > + * assume there's a maximum number of PDs that can be > >>allocated. > >>> > > + * We don't actually have this limit, but we fail the test if > >>> > > + * we allow allocations of more than we report for this > >>value. > >>> > > + */ > >>> > > >>> > Why not trap this in user space, rather than forcing the kernel to > >>> support some test program? > >>> > > >>> > >>> What do you mean "trap this in user space"? This code is not supporting > >>> any > >>> particular test program. > >>> > >>> If users try and allocate more protection domains then are advertised > >>then > >>> an > >>> error should be returned. > >>> > >>> Perhaps the comment should be removed if it is confusing? > >> > >>There is no theoretical limit on the number of PDs, or likely most other > >>resources. So why define and enforce an arbitrary limit? The > >>justification > >>given was that some test program would fail. If there's a concern about > >>that > >>test program passing, then enforce the limit in user space. > > > >I did not interpret this as being driven by a test but rather by the IBTA > >spec. > > > >This may be pedantic but, wouldn't it be confusing from a user POV to see > >an > >advertised limit but then not be constrained by it? I'm not opposed to > >setting > >this limit arbitrarily high, but I still think the implementation should > >enforce that limit. > > > >> > >>I didn't find the comment confusing. Just the choice to let a test app > >>drive the design. > > > >Perhaps "confusing" is the wrong word. But I did not interpreted the > >comment > >as saying that the implementation was driven but a test program. > > How about I reword the comment to say that while we could continue > allocating PDs being only constrained by system resources, the spec says > there is a limit so we enforce that?
I'm ok with that, Sean? Ira > > -Denny -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html