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SubjectRe: Linux Kernel -Doubt on sk_buff!
From
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jalaja@teil.soft.net (G Jalaja Devi) writes:

> 1. When an IP packet is received from IP, do we get a chain of data ( as in
> ifnet ) or is it a continuous buffer.

It is a continuous buffer. I find it curious that you use ifnet as a synonym
for BSD.

>
> 2. What is the use of the following fields in the sk_buff structure
> 1. data_skb pointer.
> 2. count.
> 3. users.

data_skb points to the original skb for cloned skbs.
count it is the reference count of the data portion
users is how many users the skbuff header has.

[BTW in 2.2 data_skb is gone and a reference count is kept at the end of
the data]

>
> 3. If we have to send a particular IP packet ( which is in sk_buff format )
> to two diffrent destinations, do we have to duplicate the sk_buff.
> Doesn't this reduce the performance.
> Is there any other way to handle this case.

skb_clone(). It only duplicates the skbuff header, but not the packet data.


http://www.uk.linux.org/Documents/buffers.html may be helpful for more
information.

-Andi

--
This is like TV. I don't like TV.

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