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

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Date:   Mon, 8 Nov 2021 20:32:14 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Jason Wang <jasowang@...hat.com>
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()'

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?

CJ

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