linux-kernel - RE: [PATCH] function mana_hwc_create

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Date:   Thu, 10 Jun 2021 20:03:23 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     Dhiraj Shah <find.dhiraj@...il.com>
CC:     KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Shachar Raindel <shacharr@...rosoft.com>,
        Colin Ian King <colin.king@...onical.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] function mana_hwc_create_wq leaks memory

> From: Dhiraj Shah <find.dhiraj@...il.com>
> Sent: Thursday, June 10, 2021 12:53 PM
>  ...
> Hi Dexuan,
> 
> Thanks for the feedback.
> 
> You are right saying ‘mana_hwc_destroy_wq' free’s up the queue.
> 
> However for example if  function 'mana_hwc_alloc_dma_buf' fails it will goto
> ‘out' and call ‘mana_hwc_destroy_wq', the value 'hwc_wq->gdma_wq' is
> still not assigned at this point. In the  ‘mana_hwc_destroy_wq' function i see

At this point, hwc_wq->gdma_wq stays with its default value NULL.

> it checks for 'hwc_wq->gdma_wq' before calling, ‘mana_gd_destroy_queue',
> which makes me think queue is still not freed.

IMO the current code is not buggy, though I admit it's not very readable. :-)

If you're interested, you're welcome to help make it more readable. I'll also
try to make some time on this.

Thanks,
Dexuan