Hi,

 

http://lists.openfabrics.org/pipermail/general/2008-July/052458.html

 

This might help you.

 

 

 

 

 

From: kernelnewbies-bounces@kernelnewbies.org
[mailto:kernelnewbies-bounces at kernelnewbies.org] On Behalf Of rohan puri
Sent: 28 November 2011 12:36
To: Vimal; kernelnewbies
Subject: Re: What is RTNL lock?

 

 

On Mon, Nov 28, 2011 at 12:19 PM, Vimal [off-list ref] wrote:

Hi Rohan

Yes, I understood this part, but I am wondering what is the purpose of
this lock.   I am guessing it's to protect all network related
operations from critical events, for e.g.: protecting a packet
transmit during device removal, protecting routing table entry during
route lookup, etc., but I can't find its precise documentation
anywhere.   Thanks,


On 27 November 2011 22:44, rohan puri [off-list ref] wrote:

On Sun, Nov 27, 2011 at 10:37 PM, Vimal [off-list ref] wrote:

quoted

Hi all,

In the Linux networking code, I see a lot of comments that say "Must
be called with RTNL lock."

What is this lock?  I tried searching for it but couldn't find any
explanation on what it is...

Thanks
--
Vimal

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Hello Vimal,
This is a mutex named rtnl_mutex. Refer file net/core/rtnetlink.c
static DEFINE_MUTEX(rtnl_mutex);

void rtnl_lock(void)
{
        mutex_lock(&rtnl_mutex);
}
EXPORT_SYMBOL(rtnl_lock);
Where ever you see those comments indicate that this mutex is to be held
before execution of that code path.
Regards,
Rohan

--
Vimal

This lock is used to serialize changes to net_device instances from runtime
events, conf changes

 

Refer book understanding Linux network internals for more details.

 

Regards,

Rohan Puri

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