Re: [PATCH] virtio-net: fix the kzalloc/kfree mismatch problem

在 2021/6/2 下午1:50, Leon Romanovsky 写道:

On Mon, May 24, 2021 at 10:37:14AM +0800, Jason Wang wrote:

quoted

在 2021/5/24 上午10:06, Xuan Zhuo 写道:

quoted

On Mon, 24 May 2021 01:48:53 +0000, Guodeqing (A) [off-list ref] wrote:

quoted

quoted

-----Original Message-----
From: Max Gurtovoy [mailto:mgurtovoy@nvidia.com]
Sent: Sunday, May 23, 2021 15:25
To: Guodeqing (A) <redacted>; mst@redhat.com
Cc: jasowang@redhat.com; davem@davemloft.net; kuba@kernel.org;
virtualization@lists.linux-foundation.org; netdev@vger.kernel.org
Subject: Re: [PATCH] virtio-net: fix the kzalloc/kfree mismatch problem


On 5/22/2021 11:02 AM, guodeqing wrote:

quoted

If the virtio_net device does not suppurt the ctrl queue feature, the
vi->ctrl was not allocated, so there is no need to free it.

you don't need this check.

from kfree doc:

"If @objp is NULL, no operation is performed."

This is not a bug. I've set vi->ctrl to be NULL in case !vi->has_cvq.

    yes,  this is not a bug, the patch is just a optimization, because the vi->ctrl maybe
    be freed which  was not allocated, this may give people a misunderstanding.
    Thanks.

I think it may be enough to add a comment, and the code does not need to be
modified.

Thanks.

Or even just leave the current code as is. A lot of kernel codes was wrote
under the assumption that kfree() should deal with NULL.

It is not assumption but standard practice that can be seen as side
effect of "7) Centralized exiting of functions" section of coding-style.rst.

Thanks

I don't see the connection to the centralized exiting.

Something like:

if (foo)
     kfree(foo);

won't break the centralization.

Thanks