From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Ferruh Yigit <ferruh.yigit@intel.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 20:50:26 +0100 [thread overview]
Message-ID: <8f2a2b11-27f0-0602-c9b0-f40c2d6384c7@redhat.com> (raw)
In-Reply-To: <590b480d-e2db-b299-82da-bc96a556a5e9@intel.com>
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.
>
>>
>> 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 19:50 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 [this message]
2018-11-22 22:04 ` Ferruh Yigit
2018-11-22 22:14 ` Ferruh Yigit
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