From: Lennert Buytenhek <[EMAIL PROTECTED]> Date: Mon, 11 Jul 2005 11:31:45 +0200
> Interesting material. What happens if there is an skb with paged > data (say, a page cache page) on the sk_write_queue, and it ends up > having to be retransmitted -- is it possible that the retransmit is > sent with different data if the page is modified in the meanwhile? Yep. We grab references to the pages, but we do not lock the _contents_. This was a deliberate design decision. This is why we only support scatter-gather (and thus paged SKB transmission by a device) when checksum offloading is being done. This is why, for example, SAMBA will only use sendfile() when the SMB client has an oplock held on the file (and thus the file contents are guarenteed to not change). It turns out that Microsoft's Windows client SMB grabs the oplocks when you open a file by default, so this is rarely a performance problem. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
