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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-dev] [PATCH] vhost: fix packed ring defines declaration
Date: Thu, 22 Nov 2018 19:51:08 +0100	[thread overview]
Message-ID: <5437708e-d8cf-fe17-6fd6-fad67b3a0eb7@redhat.com> (raw)
In-Reply-To: <be131e16-1fe8-a02b-8299-76f3a17a07d1@intel.com>



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.

>> -
>> -#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).

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
>>    */
>>
> 

  reply	other threads:[~2018-11-22 18:51 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-22 17:09 Maxime Coquelin
2018-11-22 18:23 ` Ferruh Yigit
2018-11-22 18:51   ` Maxime Coquelin [this message]
2018-11-22 19:20     ` Ferruh Yigit
2018-11-22 19:50       ` Maxime Coquelin
2018-11-22 22:04         ` Ferruh Yigit
2018-11-22 22:14 ` Ferruh Yigit

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