Messages in this thread | | | Date | Fri, 21 Nov 2014 19:39:11 +0000 | From | Al Viro <> | Subject | Re: [RFC] situation with csum_and_copy_... API |
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On Fri, Nov 21, 2014 at 05:42:55PM +0000, David Laight wrote:
> Callers of kernel_send/recvmsg() could easily be using a wrapper > function that creates the 'msghdr'. > When the want to send the remaining part of a buffer the old iterator > will no longer be available - just the original iov and the required offset.
Er... So why not copy a struct iov_iter to/from msg->msg_iter, then? It's not as it had been particulary large - 5 words isn't much...
I'm not at all sure that _anything_ has valid reasons for draining iovecs. Maintaining a struct iov_iter and modifying it is easy and actually faster...
Right now the main examples outside of net/* are due to unfortunate limitations of ->sendmsg() - until now it had no way to be told that desired data starts at offset. With ->msg_iter it obviously becomes possible...
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