[PATCH 7/7] libvhost-user: Switch to unsigned int for inuse field in struct VuVirtq

[PATCH 7/7] libvhost-user: Switch to unsigned int for inuse field in struct VuVirtq

[Marcel Holtmann]

It seems there is no need to keep the inuse field signed and end up with
compiler warnings for sign-compare.

  CC       libvhost-user.o
libvhost-user.c: In function ‘vu_queue_pop’:
libvhost-user.c:2763:19: error: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
 2763 |     if (vq->inuse >= vq->vring.num) {
      |                   ^~
libvhost-user.c: In function ‘vu_queue_rewind’:
libvhost-user.c:2808:13: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘int’ [-Werror=sign-compare]
 2808 |     if (num > vq->inuse) {
      |             ^

Instead of casting the comparision to unsigned int, just make the inuse
field unsigned int in the fist place.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
---
 subprojects/libvhost-user/libvhost-user.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
index aea7ec5061d5..8cda9b8f577a 100644
--- a/subprojects/libvhost-user/libvhost-user.h
+++ b/subprojects/libvhost-user/libvhost-user.h
@@ -343,7 +343,7 @@ typedef struct VuVirtq {
     /* Notification enabled? */
     bool notification;
 
-    int inuse;
+    unsigned int inuse;
 
     vu_queue_handler_cb handler;
 
-- 
2.38.1

Re: [PATCH 7/7] libvhost-user: Switch to unsigned int for inuse field in struct VuVirtq

[Philippe Mathieu-Daudé]

On 19/12/22 18:53, Marcel Holtmann wrote:
> It seems there is no need to keep the inuse field signed and end up with
> compiler warnings for sign-compare.
> 
>    CC       libvhost-user.o
> libvhost-user.c: In function ‘vu_queue_pop’:
> libvhost-user.c:2763:19: error: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
>   2763 |     if (vq->inuse >= vq->vring.num) {
>        |                   ^~
> libvhost-user.c: In function ‘vu_queue_rewind’:
> libvhost-user.c:2808:13: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘int’ [-Werror=sign-compare]
>   2808 |     if (num > vq->inuse) {
>        |             ^
> 
> Instead of casting the comparision to unsigned int, just make the inuse
> field unsigned int in the fist place.
> 
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
> ---
>   subprojects/libvhost-user/libvhost-user.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
> index aea7ec5061d5..8cda9b8f577a 100644
> --- a/subprojects/libvhost-user/libvhost-user.h
> +++ b/subprojects/libvhost-user/libvhost-user.h
> @@ -343,7 +343,7 @@ typedef struct VuVirtq {
>       /* Notification enabled? */
>       bool notification;
>   
> -    int inuse;
> +    unsigned int inuse;

Another use in subprojects/libvduse/libvduse.c.

Possibly both could be renamed refcount which is more meaningful.

Anyhow,
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH 7/7] libvhost-user: Switch to unsigned int for inuse field in struct VuVirtq

[Marcel Holtmann]

Hi Philippe,

>> It seems there is no need to keep the inuse field signed and end up with
>> compiler warnings for sign-compare.
>>   CC       libvhost-user.o
>> libvhost-user.c: In function ‘vu_queue_pop’:
>> libvhost-user.c:2763:19: error: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
>>  2763 |     if (vq->inuse >= vq->vring.num) {
>>       |                   ^~
>> libvhost-user.c: In function ‘vu_queue_rewind’:
>> libvhost-user.c:2808:13: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘int’ [-Werror=sign-compare]
>>  2808 |     if (num > vq->inuse) {
>>       |             ^
>> Instead of casting the comparision to unsigned int, just make the inuse
>> field unsigned int in the fist place.
>> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
>> ---
>>  subprojects/libvhost-user/libvhost-user.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
>> index aea7ec5061d5..8cda9b8f577a 100644
>> --- a/subprojects/libvhost-user/libvhost-user.h
>> +++ b/subprojects/libvhost-user/libvhost-user.h
>> @@ -343,7 +343,7 @@ typedef struct VuVirtq {
>>      /* Notification enabled? */
>>      bool notification;
>>  -    int inuse;
>> +    unsigned int inuse;
> 
> Another use in subprojects/libvduse/libvduse.c.
> 
> Possibly both could be renamed refcount which is more meaningful.

I quickly tried libvduse.[ch] and it has clearly less warnings than
libvhost-user, but some things could be applied there as well.

I looks like only the _GNU_SOURCE and the unsigned int inuse are
applicable, but there is a strict-aliasing issue that I first have
to fully understand.

If patches are acceptable, I send them as well for libvduse.

Regards

Marcel

Re: [PATCH 7/7] libvhost-user: Switch to unsigned int for inuse field in struct VuVirtq

[Michael S. Tsirkin]

On Mon, Dec 19, 2022 at 06:53:37PM +0100, Marcel Holtmann wrote:
> It seems there is no need to keep the inuse field signed and end up with
> compiler warnings for sign-compare.
> 
>   CC       libvhost-user.o
> libvhost-user.c: In function ‘vu_queue_pop’:
> libvhost-user.c:2763:19: error: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
>  2763 |     if (vq->inuse >= vq->vring.num) {
>       |                   ^~
> libvhost-user.c: In function ‘vu_queue_rewind’:
> libvhost-user.c:2808:13: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘int’ [-Werror=sign-compare]
>  2808 |     if (num > vq->inuse) {
>       |             ^
> 
> Instead of casting the comparision to unsigned int, just make the inuse
> field unsigned int in the fist place.
> 
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>


Is this a part of a patchset? No threading visible and I'd rather not
guess.

> ---
>  subprojects/libvhost-user/libvhost-user.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
> index aea7ec5061d5..8cda9b8f577a 100644
> --- a/subprojects/libvhost-user/libvhost-user.h
> +++ b/subprojects/libvhost-user/libvhost-user.h
> @@ -343,7 +343,7 @@ typedef struct VuVirtq {
>      /* Notification enabled? */
>      bool notification;
>  
> -    int inuse;
> +    unsigned int inuse;
>  
>      vu_queue_handler_cb handler;
>  
> -- 
> 2.38.1
> 
> 
> 

Re: [PATCH 7/7] libvhost-user: Switch to unsigned int for inuse field in struct VuVirtq

[Marcel Holtmann]

Hi Michael,

>> It seems there is no need to keep the inuse field signed and end up with
>> compiler warnings for sign-compare.
>> 
>>  CC       libvhost-user.o
>> libvhost-user.c: In function ‘vu_queue_pop’:
>> libvhost-user.c:2763:19: error: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
>> 2763 |     if (vq->inuse >= vq->vring.num) {
>>      |                   ^~
>> libvhost-user.c: In function ‘vu_queue_rewind’:
>> libvhost-user.c:2808:13: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘int’ [-Werror=sign-compare]
>> 2808 |     if (num > vq->inuse) {
>>      |             ^
>> 
>> Instead of casting the comparision to unsigned int, just make the inuse
>> field unsigned int in the fist place.
>> 
>> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
> 
> 
> Is this a part of a patchset? No threading visible and I'd rather not
> guess.

I am going to re-send both series as v2.

Regards

Marcel