linux-kernel - Re: [PATCH 1/2] eni_vdpa: Fix an error handling path in 'eni_vdpa_probe()'

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Message-ID: <20211125020139-mutt-send-email-mst@kernel.org>
Date:   Thu, 25 Nov 2021 02:02:50 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Jason Wang <jasowang@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        kernel-janitors@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        Wu Zongyong <wuzongyong@...ux.alibaba.com>
Subject: Re: [PATCH 1/2] eni_vdpa: Fix an error handling path in
 'eni_vdpa_probe()'

On Thu, Nov 25, 2021 at 07:34:02AM +0100, Christophe JAILLET wrote:
> Le 25/11/2021 à 00:58, Michael S. Tsirkin a écrit :
> > On Tue, Nov 09, 2021 at 10:21:44PM +0100, Christophe JAILLET wrote:
> > > Le 09/11/2021 à 03:54, Jason Wang a écrit :
> > > > On Tue, Nov 9, 2021 at 3:32 AM Christophe JAILLET
> > > > <christophe.jaillet@...adoo.fr> wrote:
> > > > > 
> > > > > Le 08/11/2021 à 06:55, Jason Wang a écrit :
> > > > > > On Mon, Nov 8, 2021 at 12:15 AM Christophe JAILLET
> > > > > > <christophe.jaillet@...adoo.fr> wrote:
> > > > > > > 
> > > > > > > In the error handling path, a successful 'vp_legacy_probe()' should be
> > > > > > > balanced by a corresponding 'vp_legacy_remove()' call, as already done in
> > > > > > > the remove function.
> > > > > > > 
> > > > > > > Add the missing call and update gotos accordingly.
> > > > > > > 
> > > > > > > Fixes: e85087beedca ("eni_vdpa: add vDPA driver for Alibaba ENI")
> > > > > > > Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> > > > > > > ---
> > > > > > >     drivers/vdpa/alibaba/eni_vdpa.c | 6 ++++--
> > > > > > >     1 file changed, 4 insertions(+), 2 deletions(-)
> > > > > > > 
> > > > > > > diff --git a/drivers/vdpa/alibaba/eni_vdpa.c b/drivers/vdpa/alibaba/eni_vdpa.c
> > > > > > > index 3f788794571a..12b3db6b4517 100644
> > > > > > > --- a/drivers/vdpa/alibaba/eni_vdpa.c
> > > > > > > +++ b/drivers/vdpa/alibaba/eni_vdpa.c
> > > > > > > @@ -501,7 +501,7 @@ static int eni_vdpa_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > > > > > >            if (!eni_vdpa->vring) {
> > > > > > >                    ret = -ENOMEM;
> > > > > > >                    ENI_ERR(pdev, "failed to allocate virtqueues\n");
> > > > > > > -               goto err;
> > > > > > > +               goto err_remove_vp_legacy;
> > > > > > >            }
> > > > > > > 
> > > > > > >            for (i = 0; i < eni_vdpa->queues; i++) {
> > > > > > > @@ -513,11 +513,13 @@ static int eni_vdpa_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > > > > > >            ret = vdpa_register_device(&eni_vdpa->vdpa, eni_vdpa->queues);
> > > > > > >            if (ret) {
> > > > > > >                    ENI_ERR(pdev, "failed to register to vdpa bus\n");
> > > > > > > -               goto err;
> > > > > > > +               goto err_remove_vp_legacy;
> > > > > > >            }
> > > > > > > 
> > > > > > >            return 0;
> > > > > > > 
> > > > > > > +err_remove_vp_legacy:
> > > > > > > +       vp_legacy_remove(&eni_vdpa->ldev);
> > > > > > 
> > > > > > Won't vp_legacy_remove() be triggered by the put_devic() below?
> > > > > 
> > > > > Hi, I'm sorry but i don't see how.
> > > > > 
> > > > > My understanding is that:
> > > > >      - on "put_device(&eni_vdpa->vdpa.dev);", the corresponding release
> > > > > function will be called.
> > > > > 
> > > > >      - This release function is the one recorded in the
> > > > > '__vdpa_alloc_device()' function.
> > > > > 
> > > > >      - So it should be 'vdpa_release_dev()'.
> > > > > 
> > > > >      - This function, AFAIU, has no knowledge of 'vp_legacy_remove()' or
> > > > > anything that could call it.
> > > > > 
> > > > > 
> > > > > Unless I misread something or miss something obvious, I don't see how
> > > > > 'vp_legacy_remove() would be called.
> > > > > 
> > > > > 
> > > > > Could you elaborate?
> > > > 
> > > > I think the device should release the driver (see
> > > > device_release_driver()) during during its deleting.
> > > 
> > > Hi, I still don't follow the logic and I don't understand how
> > > 'vp_legacy_remove()' will finely be called, but it is not that important.
> > > 
> > > If it's fine for you, it's fine for me :)
> > > 
> > > CJ
> > 
> > So pls post just patch 2?
> 
> Patch 2/2 should apply cleanly with or without patch 1/2.
> Do I really need to send a v2 just for dropping the first patch? :/
> 
> CJ

It is preferable, yes. A patch in isolation is not the same as a patch
in the series.

> > 
> > > > 
> > > > Thanks
> > > > 
> > > > > 
> > > > > CJ
> > > > > 
> > > > > > 
> > > > > > Thanks
> > > > > > 
> > > > > > >     err:
> > > > > > >            put_device(&eni_vdpa->vdpa.dev);
> > > > > > >            return ret;
> > > > > > > --
> > > > > > > 2.30.2
> > > > > > > 
> > > > > > 
> > > > > > 
> > > > > 
> > > > 
> > > > _______________________________________________
> > > > Virtualization mailing list
> > > > Virtualization@...ts.linux-foundation.org
> > > > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
> > > > 
> > 
> > 

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