netdev - Re: [net-next 1/1] tipc: eliminate buffer cloning in function tipc_msg

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Date:   Sat, 30 Jun 2018 20:48:41 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     jon.maloy@...csson.com
Cc:     netdev@...r.kernel.org,
        mohan.krishna.ghanta.krishnamurthy@...csson.com,
        tung.q.nguyen@...tech.com.au, hoang.h.le@...tech.com.au,
        canh.d.luu@...tech.com.au, ying.xue@...driver.com,
        tipc-discussion@...ts.sourceforge.net
Subject: Re: [net-next 1/1] tipc: eliminate buffer cloning in function
 tipc_msg_extract()

From: Jon Maloy <jon.maloy@...csson.com>
Date: Thu, 28 Jun 2018 22:25:04 +0200

> From: Tung Nguyen <tung.q.nguyen@...tech.com.au>
> 
> The function tipc_msg_extract() is using skb_clone() to clone inner
> messages from a message bundle buffer. Although this method is safe,
> it has an undesired effect that each buffer clone inherits the
> true-size of the bundling buffer. As a result, the buffer clone
> almost always ends up with being copied anyway by the message
> validation function. This makes the cloning into a sub-optimization.
> 
> In this commit we take the consequence of this realization, and copy
> each inner message to a separately allocated buffer up front in the
> extraction function.
> 
> As a bonus we can now eliminate the two cases where we had to copy
> re-routed packets that may potentially go out on the wire again.
> 
> Signed-off-by: Tung Nguyen <tung.q.nguyen@...tech.com.au>
> Signed-off-by: Jon Maloy <jon.maloy@...csson.com>

Applied, thanks for following up on this issue.