[PATCH v2] vhost: fix build

[PATCH v2] vhost: fix build

[Min Zhou]

On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
compile DPDK, gcc shows a following warning which will cause
build to fail when build is run with -werror:

In function 'mbuf_to_desc',
    inlined from 'vhost_enqueue_async_packed' at ../lib/vhost/virtio_net.c:1826:6,
    inlined from 'virtio_dev_rx_async_packed' at ../lib/vhost/virtio_net.c:1840:6,
    inlined from 'virtio_dev_rx_async_submit_packed.constprop' at ../lib/vhost/virtio_net.c:1900:7:
../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may be used uninitialized [-Werror=maybe-uninitialized]
 1161 |         buf_len = buf_vec[vec_idx].buf_len;
      |                   ~~~~~~~~~~~~~~~~^~~~~~~~
../lib/vhost/virtio_net.c: In function 'virtio_dev_rx_async_submit_packed.constprop':
../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
 1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
      |                           ^~~~~~~
cc1: all warnings being treated as errors

Actually, there are eight places to see the same codes in the file
lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
initialized by sub-function calls under various conditions.

Although It's hard to understand why gcc just emits warning at one
of the eight places, adding validity checks for array length is
reasonable and can also fix the warning.

Signed-off-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Min Zhou <zhoumin@loongson.cn>
---
 lib/vhost/virtio_net.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index 35fa4670fd..99233f1759 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -1153,7 +1153,7 @@ mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
 	struct vhost_async *async = vq->async;
 
-	if (unlikely(m == NULL))
+	if (unlikely(m == NULL || nr_vec == 0))
 		return -1;
 
 	buf_addr = buf_vec[vec_idx].buf_addr;
@@ -2673,6 +2673,9 @@ desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	struct vhost_async *async = vq->async;
 	struct async_inflight_info *pkts_info;
 
+	if (unlikely(nr_vec == 0))
+		return -1;
+
 	buf_addr = buf_vec[vec_idx].buf_addr;
 	buf_iova = buf_vec[vec_idx].buf_iova;
 	buf_len = buf_vec[vec_idx].buf_len;
-- 
2.31.1

Re: [PATCH v2] vhost: fix build

[zhoumin]

Sincerely ping.


On 2022年08月29日 16:29, Min Zhou wrote:
> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
> compile DPDK, gcc shows a following warning which will cause
> build to fail when build is run with -werror:
>
> In function 'mbuf_to_desc',
>      inlined from 'vhost_enqueue_async_packed' at ../lib/vhost/virtio_net.c:1826:6,
>      inlined from 'virtio_dev_rx_async_packed' at ../lib/vhost/virtio_net.c:1840:6,
>      inlined from 'virtio_dev_rx_async_submit_packed.constprop' at ../lib/vhost/virtio_net.c:1900:7:
> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may be used uninitialized [-Werror=maybe-uninitialized]
>   1161 |         buf_len = buf_vec[vec_idx].buf_len;
>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~
> ../lib/vhost/virtio_net.c: In function 'virtio_dev_rx_async_submit_packed.constprop':
> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>   1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>        |                           ^~~~~~~
> cc1: all warnings being treated as errors
>
> Actually, there are eight places to see the same codes in the file
> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
> initialized by sub-function calls under various conditions.
>
> Although It's hard to understand why gcc just emits warning at one
> of the eight places, adding validity checks for array length is
> reasonable and can also fix the warning.
>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
> ---
>   lib/vhost/virtio_net.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index 35fa4670fd..99233f1759 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -1153,7 +1153,7 @@ mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   	struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
>   	struct vhost_async *async = vq->async;
>   
> -	if (unlikely(m == NULL))
> +	if (unlikely(m == NULL || nr_vec == 0))
>   		return -1;
>   
>   	buf_addr = buf_vec[vec_idx].buf_addr;
> @@ -2673,6 +2673,9 @@ desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   	struct vhost_async *async = vq->async;
>   	struct async_inflight_info *pkts_info;
>   
> +	if (unlikely(nr_vec == 0))
> +		return -1;
> +
>   	buf_addr = buf_vec[vec_idx].buf_addr;
>   	buf_iova = buf_vec[vec_idx].buf_iova;
>   	buf_len = buf_vec[vec_idx].buf_len;

--
Thanks,
Min Zhou

Re: [PATCH v2] vhost: fix build

[zhoumin]

Kindly ping.

Any feedback is appreciated.


On 2022年08月29日 16:29, Min Zhou wrote:
> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
> compile DPDK, gcc shows a following warning which will cause
> build to fail when build is run with -werror:
>
> In function 'mbuf_to_desc',
>      inlined from 'vhost_enqueue_async_packed' at ../lib/vhost/virtio_net.c:1826:6,
>      inlined from 'virtio_dev_rx_async_packed' at ../lib/vhost/virtio_net.c:1840:6,
>      inlined from 'virtio_dev_rx_async_submit_packed.constprop' at ../lib/vhost/virtio_net.c:1900:7:
> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may be used uninitialized [-Werror=maybe-uninitialized]
>   1161 |         buf_len = buf_vec[vec_idx].buf_len;
>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~
> ../lib/vhost/virtio_net.c: In function 'virtio_dev_rx_async_submit_packed.constprop':
> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>   1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>        |                           ^~~~~~~
> cc1: all warnings being treated as errors
>
> Actually, there are eight places to see the same codes in the file
> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
> initialized by sub-function calls under various conditions.
>
> Although It's hard to understand why gcc just emits warning at one
> of the eight places, adding validity checks for array length is
> reasonable and can also fix the warning.
>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
> ---
>   lib/vhost/virtio_net.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index 35fa4670fd..99233f1759 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -1153,7 +1153,7 @@ mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   	struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
>   	struct vhost_async *async = vq->async;
>   
> -	if (unlikely(m == NULL))
> +	if (unlikely(m == NULL || nr_vec == 0))
>   		return -1;
>   
>   	buf_addr = buf_vec[vec_idx].buf_addr;
> @@ -2673,6 +2673,9 @@ desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
>   	struct vhost_async *async = vq->async;
>   	struct async_inflight_info *pkts_info;
>   
> +	if (unlikely(nr_vec == 0))
> +		return -1;
> +
>   	buf_addr = buf_vec[vec_idx].buf_addr;
>   	buf_iova = buf_vec[vec_idx].buf_iova;
>   	buf_len = buf_vec[vec_idx].buf_len;

RE: [PATCH v2] vhost: fix build

[Xia, Chenbo]

Hi Min,

> -----Original Message-----
> From: Min Zhou <zhoumin@loongson.cn>
> Sent: Monday, August 29, 2022 4:29 PM
> To: david.marchand@redhat.com; maxime.coquelin@redhat.com; Xia, Chenbo
> <chenbo.xia@intel.com>; zhoumin@loongson.cn
> Cc: dev@dpdk.org; maobibo@loongson.cn
> Subject: [PATCH v2] vhost: fix build
> 
> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
> compile DPDK, gcc shows a following warning which will cause
> build to fail when build is run with -werror:
> 
> In function 'mbuf_to_desc',
>     inlined from 'vhost_enqueue_async_packed'
> at ../lib/vhost/virtio_net.c:1826:6,
>     inlined from 'virtio_dev_rx_async_packed'
> at ../lib/vhost/virtio_net.c:1840:6,
>     inlined from 'virtio_dev_rx_async_submit_packed.constprop'
> at ../lib/vhost/virtio_net.c:1900:7:
> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may be used
> uninitialized [-Werror=maybe-uninitialized]
>  1161 |         buf_len = buf_vec[vec_idx].buf_len;
>       |                   ~~~~~~~~~~~~~~~~^~~~~~~~
> ../lib/vhost/virtio_net.c: In function
> 'virtio_dev_rx_async_submit_packed.constprop':
> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>  1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>       |                           ^~~~~~~
> cc1: all warnings being treated as errors
> 
> Actually, there are eight places to see the same codes in the file
> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
> initialized by sub-function calls under various conditions.
> 
> Although It's hard to understand why gcc just emits warning at one
> of the eight places, adding validity checks for array length is
> reasonable and can also fix the warning.
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
> ---
>  lib/vhost/virtio_net.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Just want you to know that your patch is still pending because by accident
your fix is almost the same as a previous patch that fixes a real issue but
that patch is still in progress:

http://patchwork.dpdk.org/project/dpdk/patch/20220802004938.23670-2-cfontana@suse.de/

Thanks,
Chenbo

> 
> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index 35fa4670fd..99233f1759 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -1153,7 +1153,7 @@ mbuf_to_desc(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
>  	struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
>  	struct vhost_async *async = vq->async;
> 
> -	if (unlikely(m == NULL))
> +	if (unlikely(m == NULL || nr_vec == 0))
>  		return -1;
> 
>  	buf_addr = buf_vec[vec_idx].buf_addr;
> @@ -2673,6 +2673,9 @@ desc_to_mbuf(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
>  	struct vhost_async *async = vq->async;
>  	struct async_inflight_info *pkts_info;
> 
> +	if (unlikely(nr_vec == 0))
> +		return -1;
> +
>  	buf_addr = buf_vec[vec_idx].buf_addr;
>  	buf_iova = buf_vec[vec_idx].buf_iova;
>  	buf_len = buf_vec[vec_idx].buf_len;
> --
> 2.31.1

Re: [PATCH v2] vhost: fix build

[zhoumin]

Hi Chenbo,


On Mon, 26 Sep 2022, 10:57, Xia, Chenbo wrote:
> Hi Min,
>
>> -----Original Message-----
>> From: Min Zhou <zhoumin@loongson.cn>
>> Sent: Monday, August 29, 2022 4:29 PM
>> To: david.marchand@redhat.com; maxime.coquelin@redhat.com; Xia, Chenbo
>> <chenbo.xia@intel.com>; zhoumin@loongson.cn
>> Cc: dev@dpdk.org; maobibo@loongson.cn
>> Subject: [PATCH v2] vhost: fix build
>>
>> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
>> compile DPDK, gcc shows a following warning which will cause
>> build to fail when build is run with -werror:
>>
>> In function 'mbuf_to_desc',
>>      inlined from 'vhost_enqueue_async_packed'
>> at ../lib/vhost/virtio_net.c:1826:6,
>>      inlined from 'virtio_dev_rx_async_packed'
>> at ../lib/vhost/virtio_net.c:1840:6,
>>      inlined from 'virtio_dev_rx_async_submit_packed.constprop'
>> at ../lib/vhost/virtio_net.c:1900:7:
>> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may be used
>> uninitialized [-Werror=maybe-uninitialized]
>>   1161 |         buf_len = buf_vec[vec_idx].buf_len;
>>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~
>> ../lib/vhost/virtio_net.c: In function
>> 'virtio_dev_rx_async_submit_packed.constprop':
>> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>>   1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>>        |                           ^~~~~~~
>> cc1: all warnings being treated as errors
>>
>> Actually, there are eight places to see the same codes in the file
>> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
>> initialized by sub-function calls under various conditions.
>>
>> Although It's hard to understand why gcc just emits warning at one
>> of the eight places, adding validity checks for array length is
>> reasonable and can also fix the warning.
>>
>> Signed-off-by: David Marchand <david.marchand@redhat.com>
>> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
>> ---
>>   lib/vhost/virtio_net.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
> Just want you to know that your patch is still pending because by accident
> your fix is almost the same as a previous patch that fixes a real issue but
> that patch is still in progress:
>
> http://patchwork.dpdk.org/project/dpdk/patch/20220802004938.23670-2-cfontana@suse.de/
>
> Thanks,
> Chenbo

Thanks for your helpful reply.
I think I can drop this patch if the patch you mentioned above could be 
accepted.

Thanks,
Min Zhou
>> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
>> index 35fa4670fd..99233f1759 100644
>> --- a/lib/vhost/virtio_net.c
>> +++ b/lib/vhost/virtio_net.c
>> @@ -1153,7 +1153,7 @@ mbuf_to_desc(struct virtio_net *dev, struct
>> vhost_virtqueue *vq,
>>   	struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
>>   	struct vhost_async *async = vq->async;
>>
>> -	if (unlikely(m == NULL))
>> +	if (unlikely(m == NULL || nr_vec == 0))
>>   		return -1;
>>
>>   	buf_addr = buf_vec[vec_idx].buf_addr;
>> @@ -2673,6 +2673,9 @@ desc_to_mbuf(struct virtio_net *dev, struct
>> vhost_virtqueue *vq,
>>   	struct vhost_async *async = vq->async;
>>   	struct async_inflight_info *pkts_info;
>>
>> +	if (unlikely(nr_vec == 0))
>> +		return -1;
>> +
>>   	buf_addr = buf_vec[vec_idx].buf_addr;
>>   	buf_iova = buf_vec[vec_idx].buf_iova;
>>   	buf_len = buf_vec[vec_idx].buf_len;
>> --
>> 2.31.1

Re: [PATCH v2] vhost: fix build

[Maxime Coquelin]

Hi Min,

On 9/26/22 05:25, zhoumin wrote:
> Hi Chenbo,
> 
> 
> On Mon, 26 Sep 2022, 10:57, Xia, Chenbo wrote:
>> Hi Min,
>>
>>> -----Original Message-----
>>> From: Min Zhou <zhoumin@loongson.cn>
>>> Sent: Monday, August 29, 2022 4:29 PM
>>> To: david.marchand@redhat.com; maxime.coquelin@redhat.com; Xia, Chenbo
>>> <chenbo.xia@intel.com>; zhoumin@loongson.cn
>>> Cc: dev@dpdk.org; maobibo@loongson.cn
>>> Subject: [PATCH v2] vhost: fix build
>>>
>>> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
>>> compile DPDK, gcc shows a following warning which will cause
>>> build to fail when build is run with -werror:
>>>
>>> In function 'mbuf_to_desc',
>>>      inlined from 'vhost_enqueue_async_packed'
>>> at ../lib/vhost/virtio_net.c:1826:6,
>>>      inlined from 'virtio_dev_rx_async_packed'
>>> at ../lib/vhost/virtio_net.c:1840:6,
>>>      inlined from 'virtio_dev_rx_async_submit_packed.constprop'
>>> at ../lib/vhost/virtio_net.c:1900:7:
>>> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may be 
>>> used
>>> uninitialized [-Werror=maybe-uninitialized]
>>>   1161 |         buf_len = buf_vec[vec_idx].buf_len;
>>>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~
>>> ../lib/vhost/virtio_net.c: In function
>>> 'virtio_dev_rx_async_submit_packed.constprop':
>>> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>>>   1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>>>        |                           ^~~~~~~
>>> cc1: all warnings being treated as errors
>>>
>>> Actually, there are eight places to see the same codes in the file
>>> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
>>> initialized by sub-function calls under various conditions.
>>>
>>> Although It's hard to understand why gcc just emits warning at one
>>> of the eight places, adding validity checks for array length is
>>> reasonable and can also fix the warning.
>>>
>>> Signed-off-by: David Marchand <david.marchand@redhat.com>
>>> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
>>> ---
>>>   lib/vhost/virtio_net.c | 5 ++++-
>>>   1 file changed, 4 insertions(+), 1 deletion(-)
>> Just want you to know that your patch is still pending because by 
>> accident
>> your fix is almost the same as a previous patch that fixes a real 
>> issue but
>> that patch is still in progress:
>>
>> http://patchwork.dpdk.org/project/dpdk/patch/20220802004938.23670-2-cfontana@suse.de/
>>
>> Thanks,
>> Chenbo
> 
> Thanks for your helpful reply.
> I think I can drop this patch if the patch you mentioned above could be 
> accepted.

I just sent another patch that fixes your build issue without having to
add runtime checks:

http://patches.dpdk.org/project/dpdk/patch/20221005144859.70717-1-maxime.coquelin@redhat.com/

Thanks,
Maxime

Re: [PATCH v2] vhost: fix build

[zhoumin]

Hi, Maxime,

Thanks a lot for your kind reply.

This patch is very useful and relieves the concerns in my heart.


On Wed, Oct 5, 2022 at 22:51, Maxime Coquelin wrote:

> Hi Min,
>
> On 9/26/22 05:25, zhoumin wrote:
>> Hi Chenbo,
>>
>>
>> On Mon, 26 Sep 2022, 10:57, Xia, Chenbo wrote:
>>> Hi Min,
>>>
>>>> -----Original Message-----
>>>> From: Min Zhou <zhoumin@loongson.cn>
>>>> Sent: Monday, August 29, 2022 4:29 PM
>>>> To: david.marchand@redhat.com; maxime.coquelin@redhat.com; Xia, Chenbo
>>>> <chenbo.xia@intel.com>; zhoumin@loongson.cn
>>>> Cc: dev@dpdk.org; maobibo@loongson.cn
>>>> Subject: [PATCH v2] vhost: fix build
>>>>
>>>> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
>>>> compile DPDK, gcc shows a following warning which will cause
>>>> build to fail when build is run with -werror:
>>>>
>>>> In function 'mbuf_to_desc',
>>>>      inlined from 'vhost_enqueue_async_packed'
>>>> at ../lib/vhost/virtio_net.c:1826:6,
>>>>      inlined from 'virtio_dev_rx_async_packed'
>>>> at ../lib/vhost/virtio_net.c:1840:6,
>>>>      inlined from 'virtio_dev_rx_async_submit_packed.constprop'
>>>> at ../lib/vhost/virtio_net.c:1900:7:
>>>> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may 
>>>> be used
>>>> uninitialized [-Werror=maybe-uninitialized]
>>>>   1161 |         buf_len = buf_vec[vec_idx].buf_len;
>>>>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~
>>>> ../lib/vhost/virtio_net.c: In function
>>>> 'virtio_dev_rx_async_submit_packed.constprop':
>>>> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>>>>   1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>>>>        |                           ^~~~~~~
>>>> cc1: all warnings being treated as errors
>>>>
>>>> Actually, there are eight places to see the same codes in the file
>>>> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
>>>> initialized by sub-function calls under various conditions.
>>>>
>>>> Although It's hard to understand why gcc just emits warning at one
>>>> of the eight places, adding validity checks for array length is
>>>> reasonable and can also fix the warning.
>>>>
>>>> Signed-off-by: David Marchand <david.marchand@redhat.com>
>>>> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
>>>> ---
>>>>   lib/vhost/virtio_net.c | 5 ++++-
>>>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>> Just want you to know that your patch is still pending because by 
>>> accident
>>> your fix is almost the same as a previous patch that fixes a real 
>>> issue but
>>> that patch is still in progress:
>>>
>>> http://patchwork.dpdk.org/project/dpdk/patch/20220802004938.23670-2-cfontana@suse.de/ 
>>>
>>>
>>> Thanks,
>>> Chenbo
>>
>> Thanks for your helpful reply.
>> I think I can drop this patch if the patch you mentioned above could 
>> be accepted.
>
> I just sent another patch that fixes your build issue without having to
> add runtime checks:
>
> http://patches.dpdk.org/project/dpdk/patch/20221005144859.70717-1-maxime.coquelin@redhat.com/ 
>
>

OK, thanks. I have read the whole thread, which is a good job. I'd like 
thank you all for your hard work.


> Thanks,
> Maxime
>

Re: [PATCH v2] vhost: fix build

[zhoumin]

Hi, Maxime,

Thanks a lot for your kind reply.

This patch is very useful and relieves the concerns in my heart.


On Wed, Oct 5, 2022 at 22:51, Maxime Coquelin wrote:

> Hi Min,
>
> On 9/26/22 05:25, zhoumin wrote:
>> Hi Chenbo,
>>
>>
>> On Mon, 26 Sep 2022, 10:57, Xia, Chenbo wrote:
>>> Hi Min,
>>>
>>>> -----Original Message-----
>>>> From: Min Zhou <zhoumin@loongson.cn>
>>>> Sent: Monday, August 29, 2022 4:29 PM
>>>> To: david.marchand@redhat.com; maxime.coquelin@redhat.com; Xia, Chenbo
>>>> <chenbo.xia@intel.com>; zhoumin@loongson.cn
>>>> Cc: dev@dpdk.org; maobibo@loongson.cn
>>>> Subject: [PATCH v2] vhost: fix build
>>>>
>>>> On CentOS 8 or Debian 10.4 systems using gcc 12.1 to cross
>>>> compile DPDK, gcc shows a following warning which will cause
>>>> build to fail when build is run with -werror:
>>>>
>>>> In function 'mbuf_to_desc',
>>>>      inlined from 'vhost_enqueue_async_packed'
>>>> at ../lib/vhost/virtio_net.c:1826:6,
>>>>      inlined from 'virtio_dev_rx_async_packed'
>>>> at ../lib/vhost/virtio_net.c:1840:6,
>>>>      inlined from 'virtio_dev_rx_async_submit_packed.constprop'
>>>> at ../lib/vhost/virtio_net.c:1900:7:
>>>> ../lib/vhost/virtio_net.c:1161:35: error: 'buf_vec[0].buf_len' may 
>>>> be used
>>>> uninitialized [-Werror=maybe-uninitialized]
>>>>   1161 |         buf_len = buf_vec[vec_idx].buf_len;
>>>>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~
>>>> ../lib/vhost/virtio_net.c: In function
>>>> 'virtio_dev_rx_async_submit_packed.constprop':
>>>> ../lib/vhost/virtio_net.c:1838:27: note: 'buf_vec' declared here
>>>>   1838 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
>>>>        |                           ^~~~~~~
>>>> cc1: all warnings being treated as errors
>>>>
>>>> Actually, there are eight places to see the same codes in the file
>>>> lib/vhost/virtio_net.c, and all these `buf_vec` arraies are
>>>> initialized by sub-function calls under various conditions.
>>>>
>>>> Although It's hard to understand why gcc just emits warning at one
>>>> of the eight places, adding validity checks for array length is
>>>> reasonable and can also fix the warning.
>>>>
>>>> Signed-off-by: David Marchand <david.marchand@redhat.com>
>>>> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
>>>> ---
>>>>   lib/vhost/virtio_net.c | 5 ++++-
>>>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>> Just want you to know that your patch is still pending because by 
>>> accident
>>> your fix is almost the same as a previous patch that fixes a real 
>>> issue but
>>> that patch is still in progress:
>>>
>>> http://patchwork.dpdk.org/project/dpdk/patch/20220802004938.23670-2-cfontana@suse.de/ 
>>>
>>>
>>> Thanks,
>>> Chenbo
>>
>> Thanks for your helpful reply.
>> I think I can drop this patch if the patch you mentioned above could 
>> be accepted.
>
> I just sent another patch that fixes your build issue without having to
> add runtime checks:
>
> http://patches.dpdk.org/project/dpdk/patch/20221005144859.70717-1-maxime.coquelin@redhat.com/ 
>
>

OK, thanks. I have read the whole thread, which is a good job. I'd like 
thank you all for your hard work.


> Thanks,
> Maxime
>
Thanks,

Min Zhou