From: Igor Ryzhov <iryzhov@nfware.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>
Cc: dev@dpdk.org, David Marchand <david.marchand@6wind.com>,
"Liu, Yuanhan" <yuanhan.liu@intel.com>
Subject: Re: [dpdk-dev] rte_eth_dev_attach returns 0, although device is not attached
Date: Thu, 4 Aug 2016 17:54:09 +0300 [thread overview]
Message-ID: <9C1AE4BF-9530-4596-BCF6-09E9AF7E55F3@nfware.com> (raw)
In-Reply-To: <57A34175.1040204@intel.com>
> 4 авг. 2016 г., в 16:21, Ferruh Yigit <ferruh.yigit@intel.com> написал(а):
>
> On 8/4/2016 12:51 PM, Igor Ryzhov wrote:
>> Hello Ferruh,
>>
>>> 4 авг. 2016 г., в 14:33, Ferruh Yigit <ferruh.yigit@intel.com> написал(а):
>>>
>>> Hi Igor,
>>>
>>> On 8/3/2016 5:58 PM, Igor Ryzhov wrote:
>>>> Hello.
>>>>
>>>> Function rte_eth_dev_attach can return false positive result.
>>>> It happens because rte_eal_pci_probe_one returns zero if no driver is found for the device:
>>>> ret = pci_probe_all_drivers(dev);
>>>> if (ret < 0)
>>>> goto err_return;
>>>> return 0;
>>>> (pci_probe_all_drivers returns 1 in that case)
>>>>
>>>> For example, it can be easily reproduced by trying to attach virtio device, managed by kernel driver.
>>>
>>> You are right, and I did able to reproduce this issue with virtio as you
>>> suggest.
>>>
>>> But I wonder why rte_eth_dev_get_port_by_addr() is not catching this.
>>> Perhaps a dev->attached check needs to be added into this function.
>
> With a second check, rte_eth_dev_get_port_by_addr() catches it if the
> driver is missing.
>
> But for virtio case, problem is not missing driver.
> Problem is eth_virtio_dev_init() is returning a positive value on fail.
>
> Call stack is:
> rte_eal_pci_probe_one
> pci_probe_all_drivers
> rte_eal_pci_probe_one_driver
> rte_eth_dev_init
> eth_virtio_dev_init
>
> So rte_eal_pci_probe_one_driver() also returns positive value, as no
> driver found, and rte_eth_dev_get_port_by_addr() returns a valid
> port_id, since rte_eth_dev_init() allocated an eth_dev.
>
> Briefly, this can be fixed in virtio pmd, instead of eal pci.
>
>>>
>>>>
>>>> I think it should be:
>>>> ret = pci_probe_all_drivers(dev);
>>>> if (ret)
>>>> goto err_return;
>>>> return 0;
>>>
>>> Your proposal looks good to me. Will you send a patch?
>>
>
> Original code silently ignores the if driver is missing for that dev,
> although it is still questionable, I think we can keep this as it is.
>
>> Patch sent.
>
> Sorry for this, but can you please test with following modification in
> virtio:
> index 07d6449..c74eeee 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -1156,7 +1156,7 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
> if (pci_dev) {
> ret = vtpci_init(pci_dev, hw, &dev_flags);
> if (ret)
> - return ret;
> + return -1;
> }
>
> /* Reset the device although not necessary at startup */
I think it's not a good change, because it will break the idea of this patch - http://dpdk.org/browse/dpdk/commit/?id=ac5e1d83 <http://dpdk.org/browse/dpdk/commit/?id=ac5e1d83>
Also, with your patch the application will not start, because rte_eal_pci_probe will fail:
if (ret < 0)
rte_exit(EXIT_FAILURE, "Requested device " PCI_PRI_FMT
" cannot be used\n", dev->addr.domain, dev->addr.bus,
dev->addr.devid, dev->addr.function);
And now I think that maybe we should change the way rte_eal_pci_probe works.
I think we shouldn't stop the application if just one of PCI devices is not probed successfully.
>
>
>>
>>>
>>>> Best regards,
>>>> Igor
next prev parent reply other threads:[~2016-08-04 14:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-03 16:58 Igor Ryzhov
2016-08-04 11:33 ` Ferruh Yigit
2016-08-04 11:51 ` Igor Ryzhov
2016-08-04 13:21 ` Ferruh Yigit
2016-08-04 14:54 ` Igor Ryzhov [this message]
2016-08-04 15:47 ` Ferruh Yigit
2016-08-05 12:29 ` Bruce Richardson
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