patches for DPDK stable branches
 help / color / mirror / Atom feed
From: Vipul Ashri <vipul.ashri@oracle.com>
To: Andrew Rybchenko <arybchenko@solarflare.com>, dev@dpdk.org
Cc: chenbo.xia@intel.com, zhihong.wang@intel.com,
	maxime.coquelin@redhat.com,  stable@dpdk.org
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net/virtio: fix wrong variable assignment in helper macro
Date: Fri, 18 Sep 2020 10:41:04 +0000 (UTC)	[thread overview]
Message-ID: <4293b160-6fa0-4413-b674-dd245a3d18c8@default> (raw)
In-Reply-To: <7a2d66d6-3961-5251-36d2-c702fe80379f@solarflare.com>

Hi Andrew

I like your suggestion and applied with [v5] net/virtio: fix wrong variable assignment in helper macro
V4 had a extra line typos., V5 is tested compiled and pushed carefully
Thanks!

Regards
Vipul


-----Original Message-----
From: Andrew Rybchenko [mailto:arybchenko@solarflare.com] 
Sent: Saturday, 29 August, 2020 16:53
To: Vipul Ashri <vipul.ashri@oracle.com>; dev@dpdk.org
Cc: chenbo.xia@intel.com; zhihong.wang@intel.com; maxime.coquelin@redhat.com; stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] net/virtio: fix wrong variable assignment in helper macro

On 8/14/20 12:21 PM, 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 | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/virtio/virtqueue.h 
> b/drivers/net/virtio/virtqueue.h index 105a9c00c..20c95471e 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -607,10 +607,8 @@ 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_);		\
> +	if ((var) != (val))			\
> +		(var) = (val);			\

Good catch. As I understand the old code tries to avoid processing of var and val expressions twice. It looks it could be kept for val at least. Just keep if condition as in old code and fix the last line above:
    (var) = val_;
Since var_ and val_are local variables there is no necessity to enclose it in parenthesis (but does not harm if done).
var_ may be really removed since since resulting code will use it only once.


      parent reply	other threads:[~2020-09-18 10:43 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200814092138.1692-1-vipul.ashri@oracle.com>
2020-08-29 11:22 ` Andrew Rybchenko
2020-08-29 22:17   ` Edward Makarov
2020-09-18 10:46     ` Vipul Ashri
2020-09-18 10:53       ` Maxime Coquelin
2020-09-18 10:41   ` Vipul Ashri [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4293b160-6fa0-4413-b674-dd245a3d18c8@default \
    --to=vipul.ashri@oracle.com \
    --cc=arybchenko@solarflare.com \
    --cc=chenbo.xia@intel.com \
    --cc=dev@dpdk.org \
    --cc=maxime.coquelin@redhat.com \
    --cc=stable@dpdk.org \
    --cc=zhihong.wang@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).