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

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Date:   Tue, 9 Nov 2021 10:54:56 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     mst <mst@...hat.com>, Wu Zongyong <wuzongyong@...ux.alibaba.com>,
        Arnd Bergmann <arnd@...db.de>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 1/2] eni_vdpa: Fix an error handling path in 'eni_vdpa_probe()'

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.

Thanks

>
> CJ
>
> >
> > Thanks
> >
> >>   err:
> >>          put_device(&eni_vdpa->vdpa.dev);
> >>          return ret;
> >> --
> >> 2.30.2
> >>
> >
> >
>