netdev - Re: [PATCH net v3] driver: veth: Fix one possbile memleak when fail to register

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Date:   Wed, 3 May 2017 00:59:19 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     Gao Feng <gfree.wind@....163.com>
Cc:     davem <davem@...emloft.net>, jarod@...hat.com,
        Stephen Hemminger <stephen@...workplumber.org>,
        dsa@...ulusnetworks.com, network dev <netdev@...r.kernel.org>
Subject: Re: [PATCH net v3] driver: veth: Fix one possbile memleak when fail
 to register_netdevice

On Tue, May 2, 2017 at 7:03 PM, Gao Feng <gfree.wind@....163.com> wrote:
>> From: Xin Long [mailto:lucien.xin@...il.com]
>> Sent: Tuesday, May 2, 2017 3:56 PM
>> On Sat, Apr 29, 2017 at 11:51 AM,  <gfree.wind@...mail.com> wrote:
>> > From: Gao Feng <gfree.wind@...mail.com>
> [...]
>> > -static void veth_dev_free(struct net_device *dev)
>> > +static void veth_destructor_free(struct net_device *dev)
>> >  {
>> >         free_percpu(dev->vstats);
>> > +}
>> not sure why you needed to add this function.
>> to use free_percpu() directly may be clearer.
>
> Because both of ndo_uninit and destructor need to perform same free statements.
> It is good at maintain the codes with the common function.
>>
>> > +
>> > +static void veth_dev_uninit(struct net_device *dev) {
>> call free_percpu() here, no need to check dev->reg_state.
>> free_percpu will just return if dev->vstats is NULL.
>
> It would break the original design if don't check the reg_state.
> The original logic is that free the resources in the destructor, not in ndo_init.
I got what you're doing now, can you pls try to fix this with:

--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -219,10 +219,9 @@ static int veth_dev_init(struct net_device *dev)
        return 0;
 }

-static void veth_dev_free(struct net_device *dev)
+static void veth_dev_uninit(struct net_device *dev)
 {
        free_percpu(dev->vstats);
-       free_netdev(dev);
 }

 #ifdef CONFIG_NET_POLL_CONTROLLER
@@ -279,6 +278,7 @@ static void veth_set_rx_headroom(struct net_device
*dev, int new_hr)

 static const struct net_device_ops veth_netdev_ops = {
        .ndo_init            = veth_dev_init,
+       .ndo_uninit          = veth_dev_uninit,
        .ndo_open            = veth_open,
        .ndo_stop            = veth_close,
        .ndo_start_xmit      = veth_xmit,
@@ -317,7 +317,7 @@ static void veth_setup(struct net_device *dev)
                               NETIF_F_HW_VLAN_STAG_TX |
                               NETIF_F_HW_VLAN_CTAG_RX |
                               NETIF_F_HW_VLAN_STAG_RX);
-       dev->destructor = veth_dev_free;
+       dev->destructor = free_netdev;
        dev->max_mtu = ETH_MAX_MTU;

        dev->hw_features = VETH_FEATURES;


just as what other virtual nic drivers do (vxlan, geneve, macsec, bridge ....)

>
> BTW, because I send multiple patches too fast today, the email server blocks my account.
> So I have to reply you with a different email account. Sorry.
>
> Best Regards
> Feng
>
>>
> [...]
>
>