netdev - Re: [PATCH net] dsa: fix promiscuity leak on slave dev open error

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Message-ID: <CAOtvUMd0iFYDhFQT6CFvYvvTjGCNYRX2i2vqJaXf3m=+2z=_jw@mail.gmail.com>
Date:	Sun, 28 Jun 2015 16:19:28 +0300
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Andrew Lunn <andrew@...n.ch>
Cc:	Gilad Ben-Yossef <giladb@...hip.com>,
	David Miller <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Scott Feldman <sfeldma@...il.com>
Subject: Re: [PATCH net] dsa: fix promiscuity leak on slave dev open error

On Fri, Jun 26, 2015 at 6:04 PM, Andrew Lunn <andrew@...n.ch> wrote:
> On Thu, Jun 25, 2015 at 04:50:13PM +0300, giladb@...hip.com wrote:
>> From: Gilad Ben-Yossef <gilad@...yossef.com>
>>
>> DSA master netdev promiscuity counter was not being properly
>> decremented on slave device open error path.
>>
...

> Acked-by: Andrew Lunn <andrew@...n.ch>

Thank you Andrew.
>
> FYI: I grep'ed the whole kernel. This seems to be the only place 0 is
> passed to dev_set_promiscuity(), i.e. the same bug is not present
> anywhere else.
>


It has occurred to me that dev_set_promiscuity() and its brethren
dev_set_allmulti() may not be the best of interfaces:

- On cursory inspection of code using these function their name
implies the value of the relevant counter is set to the value passed
as parameter, not incremented by it.
- No caller I've managed to spot passes anything but -1 or 1

It seems an interface of

int dev_set_promiscuity(struct net_device *dev, bool on);

int dev_set_allmulti(struct net_device *dev, bool on);

would be as functional (for current users), more readable and less
error prone but I am not sure such a tiny problem (if you can call
this a problem) is worth the churn...


Gilad






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Gilad Ben-Yossef
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