>-----Original Message----- >From: Jason Gunthorpe [mailto:jgg@xxxxxxxx] >Sent: Tuesday, April 16, 2019 11:20 PM >To: Ruhl, Michael J <michael.j.ruhl@xxxxxxxxx> >Cc: Leon Romanovsky <leon@xxxxxxxxxx>; Dalessandro, Dennis ><dennis.dalessandro@xxxxxxxxx>; dledford@xxxxxxxxxx; linux- >rdma@xxxxxxxxxxxxxxx; Marciniszyn, Mike <mike.marciniszyn@xxxxxxxxx> >Subject: Re: [PATCH RESEND for-next 5/9] IB/{rdmavt, qib, hfi1}: Use new >routine to release reference counts > >On Mon, Apr 15, 2019 at 08:52:52PM +0000, Ruhl, Michael J wrote: > >> We do need the reference count because the AH is used by the >asynchronous >> send engine. > >Drivers cannot use refcounts to manage their object lifetimes. Destroy >must be synchronous. I think that that is what we are trying to address (make destroy synchronous). >So if you have AH's in use by another thread it must sleep during >destroy.. What must sleep, the other thread or the destroy? >> I am going to work up a patch to implement the SLEEPABLE path in our destroy >> to deal with this. > >I thought that was only for create? Did we get an expectation that >destroy is non-sleeping? I hope not.. Umm. The _destroy() interface has a destroy_flags parameter. My assumption for this is that if RDMA_DESTROY_AH_SLEEPABLE is set, the drivers _destroy() function must wait (sleep?) until all access (our internal refcount) to the AH is compete. Are you saying this mechanism is for the _create only? Thanks, Mike >Jason
