[v5] net/virtio: fix wrong variable assignment in helper macro
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Message ID 20200918095505.1619-1-vipul.ashri@oracle.com
State Accepted
Delegated to: Maxime Coquelin
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Series
  • [v5] net/virtio: fix wrong variable assignment in helper macro
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ci/Intel-compilation success Compilation OK
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Commit Message

Vipul Ashri Sept. 18, 2020, 9:55 a.m. UTC
Inside Macro ASSIGN_UNLESS_EQUAL(var, val), assignment to var is always
failing as assignment done using var_ having local scope only.
This leads to TX packets not going out and found broken due to cleanup
malfunctioning. This patch fixes the wrong variable assignment.

Fixes: 57f90f894588 ("net/virtio: reuse packed ring functions")
Cc: stable@dpdk.org

Signed-off-by: Vipul Ashri <vipul.ashri@oracle.com>
---
 drivers/net/virtio/virtqueue.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Maxime Coquelin Sept. 18, 2020, 12:22 p.m. UTC | #1
On 9/18/20 11:55 AM, Vipul Ashri wrote:
> Inside Macro ASSIGN_UNLESS_EQUAL(var, val), assignment to var is always
> failing as assignment done using var_ having local scope only.
> This leads to TX packets not going out and found broken due to cleanup
> malfunctioning. This patch fixes the wrong variable assignment.
> 
> Fixes: 57f90f894588 ("net/virtio: reuse packed ring functions")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Vipul Ashri <vipul.ashri@oracle.com>
> ---
>  drivers/net/virtio/virtqueue.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
> index 105a9c00c..6ed50648c 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -607,10 +607,10 @@ virtqueue_notify(struct virtqueue *vq)
>  
>  /* avoid write operation when necessary, to lessen cache issues */
>  #define ASSIGN_UNLESS_EQUAL(var, val) do {	\
> -	typeof(var) var_ = (var);		\
> -	typeof(val) val_ = (val);		\
> -	if ((var_) != (val_))			\
> -		(var_) = (val_);		\
> +	typeof(var) *const var_ = &(var);	\
> +	typeof(val)  const val_ = (val);	\
> +	if (*var_ != val_)			\
> +		*var_ = val_;			\
>  } while (0)
>  
>  #define virtqueue_clear_net_hdr(hdr) do {		\
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime
Maxime Coquelin Sept. 18, 2020, 12:30 p.m. UTC | #2
On 9/18/20 11:55 AM, Vipul Ashri wrote:
> Inside Macro ASSIGN_UNLESS_EQUAL(var, val), assignment to var is always
> failing as assignment done using var_ having local scope only.
> This leads to TX packets not going out and found broken due to cleanup
> malfunctioning. This patch fixes the wrong variable assignment.
> 
> Fixes: 57f90f894588 ("net/virtio: reuse packed ring functions")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Vipul Ashri <vipul.ashri@oracle.com>
> ---
>  drivers/net/virtio/virtqueue.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Applied to dpdk-next-virtio/master.

Thanks,
Maxime

Patch
diff mbox series

diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 105a9c00c..6ed50648c 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -607,10 +607,10 @@  virtqueue_notify(struct virtqueue *vq)
 
 /* avoid write operation when necessary, to lessen cache issues */
 #define ASSIGN_UNLESS_EQUAL(var, val) do {	\
-	typeof(var) var_ = (var);		\
-	typeof(val) val_ = (val);		\
-	if ((var_) != (val_))			\
-		(var_) = (val_);		\
+	typeof(var) *const var_ = &(var);	\
+	typeof(val)  const val_ = (val);	\
+	if (*var_ != val_)			\
+		*var_ = val_;			\
 } while (0)
 
 #define virtqueue_clear_net_hdr(hdr) do {		\