linux-kernel - Re: [PATCH rdma-next v2 0/9] Restore failure of destroy commands

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Message-ID: <20200910122457.GI421756@unreal>
Date:   Thu, 10 Sep 2020 15:24:57 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     Doug Ledford <dledford@...hat.com>,
        Adit Ranadive <aditr@...are.com>,
        Ariel Elior <aelior@...vell.com>,
        Bernard Metzler <bmt@...ich.ibm.com>,
        Christian Benvenuti <benve@...co.com>,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        Devesh Sharma <devesh.sharma@...adcom.com>,
        Faisal Latif <faisal.latif@...el.com>,
        Gal Pressman <galpress@...zon.com>,
        Lijun Ou <oulijun@...wei.com>, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org,
        Michal Kalderon <mkalderon@...vell.com>,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        Naresh Kumar PBS <nareshkumar.pbs@...adcom.com>,
        Nelson Escobar <neescoba@...co.com>,
        Parvi Kaustubhi <pkaustub@...co.com>,
        Potnuri Bharat Teja <bharat@...lsio.com>,
        Selvin Xavier <selvin.xavier@...adcom.com>,
        Shiraz Saleem <shiraz.saleem@...el.com>,
        Somnath Kotur <somnath.kotur@...adcom.com>,
        Sriharsha Basavapatna <sriharsha.basavapatna@...adcom.com>,
        VMware PV-Drivers <pv-drivers@...are.com>,
        Weihang Li <liweihang@...wei.com>,
        "Wei Hu(Xavier)" <huwei87@...ilicon.com>,
        Yishai Hadas <yishaih@...dia.com>,
        Yuval Shaia <yuval.shaia@...cle.com>,
        Zhu Yanjun <yanjunz@...dia.com>
Subject: Re: [PATCH rdma-next v2 0/9] Restore failure of destroy commands

On Wed, Sep 09, 2020 at 03:06:07PM -0300, Jason Gunthorpe wrote:
> On Mon, Sep 07, 2020 at 03:09:12PM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@...dia.com>
> >
> > Changelog:
> > v2:
> >  * Rebased on top of the 524d8ffd07f0
> >  * Removed "udata" check in destroy flows
> >  * Changed ib_free_cq to return early
> >  * Used Jason's suggestion to implement "RDMA/mlx5: Issue FW command to destroy
> >    SRQ on reentry" patch.
> > v1
> >  * Changed returned value in efa_destroy_ah() from EINVAL to EOPNOTSUPP
> >  * https://lore.kernel.org/lkml/20200830084010.102381-1-leon@kernel.org
> > v0:
> >  * https://lore.kernel.org/lkml/20200824103247.1088464-1-leon@kernel.org
> >
> > Hi,
> >
> > This series restores the ability to fail on destroy commands, due to the
> > fact that mlx5_ib DEVX implementation interleaved ib_core objects
> > with FW objects without sharing reference counters.
> >
> > In retrospect, every part of the mlx5_ib flow is correct.
> >
> > It started from IBTA which was written by HW engineers with HW in mind and
> > they allowed to fail in destruction. FW implemented it with symmetrical
> > interface like any other command and propagated error back to the kernel,
> > which forwarded it to the libibverbs and kernel ULPs.
> >
> > Libibverbs was designed with IBTA spec in hand putting destroy errors in
> > stone. Up till mlx5_ib DEVX, it worked well, because the IB verbs objects
> > are counted by the kernel and ib_core ensures that FW destroy will success
> > by managing various reference counters on such objects.
> >
> > The extension of the mlx5 driver changed this flow when allowed DEVX objects
> > that are not managed by ib_core to be interleaved with the ones under ib_core
> > responsibility.
> >
> > The drivers that want to implement DEVX flows must ensure that FW/HW
> > destroys are performed as early as possible before any other internal
> > cleanup. After HW destroys, drivers are not allowed to fail.
> >
> > This series includes two patches (WQ and "potential race") that will
> > require extra work in mlx5_ib, they both theoretical. WQ is not in use
> > in DEVX, but is needed to make interface symmetrical to other objects.
> > "Potential race" is in ULP flow that ensures that SRQ is destroyed in
> > proper order.
> >
> > Thanks
> >
> > Leon Romanovsky (9):
> >   RDMA: Restore ability to fail on PD deallocate
> >   RDMA: Restore ability to fail on AH destroy
> >   RDMA/mlx5: Issue FW command to destroy SRQ on reentry
> >   RDMA: Restore ability to fail on SRQ destroy
> >   RDMA/core: Delete function indirection for alloc/free kernel CQ
> >   RDMA: Allow fail of destroy CQ
> >   RDMA: Change XRCD destroy return value
> >   RDMA: Restore ability to return error for destroy WQ
> >   RDMA: Make counters destroy symmetrical
>
> Thanks, applied to for-next with the changes I noted:

Thanks for taking care. LGTM.