From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
dev@dpdk.org, thomas@monjalon.net, tiwei.bie@intel.com,
zhihong.wang@intel.com, jfreiman@redhat.com
Cc: stable@dpdk.org
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] vhost: fix packed ring defines declaration
Date: Thu, 22 Nov 2018 22:04:51 +0000 [thread overview]
Message-ID: <8b74daec-a36f-9757-f218-91a5b6e1e553@intel.com> (raw)
In-Reply-To: <8f2a2b11-27f0-0602-c9b0-f40c2d6384c7@redhat.com>
On 11/22/2018 7:50 PM, Maxime Coquelin wrote:
>
>
> On 11/22/18 8:20 PM, Ferruh Yigit wrote:
>> On 11/22/2018 6:51 PM, Maxime Coquelin wrote:
>>>
>>>
>>> On 11/22/18 7:23 PM, Ferruh Yigit wrote:
>>>> On 11/22/2018 5:09 PM, Maxime Coquelin wrote:
>>>>> The packed ring defines were declared only if kernel
>>>>> header does not declare them.
>>>>> The problem is that they are not applied in upstream kernel,
>>>>> and some changes in the names have been required.
>>>>>
>>>>> This patch declares the defines unconditionally, which
>>>>> fixes potential build issues.
>>>>
>>>> +1 to address possible build issues.
>>>>
>>>>>
>>>>> Fixes: 297b1e7350f6 ("vhost: add virtio packed virtqueue defines")
>>>>> Cc: stable@dpdk.org
>>>>>
>>>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>>>> ---
>>>>> lib/librte_vhost/vhost.h | 22 +++++++++++-----------
>>>>> 1 file changed, 11 insertions(+), 11 deletions(-)
>>>>>
>>>>> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
>>>>> index 760f42192..5218f1b12 100644
>>>>> --- a/lib/librte_vhost/vhost.h
>>>>> +++ b/lib/librte_vhost/vhost.h
>>>>> @@ -219,13 +219,6 @@ struct vhost_msg {
>>>>>
>>>>> #define VIRTIO_F_RING_PACKED 34
>>>>>
>>>>> -#define VRING_DESC_F_NEXT 1
>>>>> -#define VRING_DESC_F_WRITE 2
>>>>> -#define VRING_DESC_F_INDIRECT 4
>>>>
>>>> Why these are not re-defined below? Not used?
>>>
>>> These defines are in kernel headers since the beginning of virtio
>>> support, so there are no reasons to keep them (and they aren't packed-
>>> ring specific).
>>>
>>> I can let them if you prefer, it does not hurt but shouldn't be here.
>>
>> Not required, I just want to confirm nothing missed.
>>
>>>
>>>>> -
>>>>> -#define VRING_DESC_F_AVAIL (1ULL << 7)
>>>>> -#define VRING_DESC_F_USED (1ULL << 15)
>>>>> -
>>>>> struct vring_packed_desc {
>>>>> uint64_t addr;
>>>>> uint32_t len;
>>>>> @@ -233,16 +226,23 @@ struct vring_packed_desc {
>>>>> uint16_t flags;
>>>>> };
>>>>>
>>>>> -#define VRING_EVENT_F_ENABLE 0x0
>>>>> -#define VRING_EVENT_F_DISABLE 0x1
>>>>> -#define VRING_EVENT_F_DESC 0x2
>>>>> -
>>>>> struct vring_packed_desc_event {
>>>>> uint16_t off_wrap;
>>>>> uint16_t flags;
>>>>> };
>>>>> #endif
>>>>>
>>>>> +/*
>>>>> + * Declare below packed ring defines unconditionally
>>>>> + * as Kernel header might use different names.
>>>>> + */
>>>>> +#define VRING_DESC_F_AVAIL (1ULL << 7)
>>>>> +#define VRING_DESC_F_USED (1ULL << 15)
>>>>> +
>>>>> +#define VRING_EVENT_F_ENABLE 0x0
>>>>> +#define VRING_EVENT_F_DISABLE 0x1
>>>>> +#define VRING_EVENT_F_DESC 0x2
>>>>
>>>> What if Linux changes mind and uses old names again, build will fail again. If
>>>> related part in Linux is not released yet, what do you think being on safe side
>>>> and adding these defines with "#ifndef" wrap?
>>>
>>> There are the "old" ones.
>>> In any case it will work (I tested it).
>>
>> I see they are the old ones but is there any chance that kernel uses them again
>> (for some odd reason) ? Which can break the build. Should we add a protection?
>
> Yes, there is a chance, but that would not break build, it will just
> override it.
It will give redefined warning if values are different but right, won't cause
any issue with same number.
>
>>
>>>
>>> In a future release, I plan to get rid of this dependency with Kernel
>>> which only causes problems.
>>>
>>> There was a benefit at the beginning when all needed declarations where
>>> in the Kernel headers. But now, every time we add a new virtio feature,
>>> we have to check kernel supports it and if not define it.
>>>
>>> Thanks,
>>> Maxime
>>>>> +
>>>>> /*
>>>>> * Available and used descs are in same order
>>>>> */
>>>>>
>>>>
>>
next prev parent reply other threads:[~2018-11-22 22:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 17:09 [dpdk-stable] " Maxime Coquelin
2018-11-22 18:23 ` [dpdk-stable] [dpdk-dev] " Ferruh Yigit
2018-11-22 18:51 ` Maxime Coquelin
2018-11-22 19:20 ` Ferruh Yigit
2018-11-22 19:50 ` Maxime Coquelin
2018-11-22 22:04 ` Ferruh Yigit [this message]
2018-11-22 22:14 ` Ferruh Yigit
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