0df7cd3c13
This is preparation patch for MSG_ZEROCOPY support. It adds handling of non-linear skbs by replacing direct calls of 'memcpy_to_msg()' with 'skb_copy_datagram_iter()'. Main advantage of the second one is that it can handle paged part of the skb by using 'kmap()' on each page, but if there are no pages in the skb, it behaves like simple copying to iov iterator. This patch also adds new field to the control block of skb - this value shows current offset in the skb to read next portion of data (it doesn't matter linear it or not). Idea behind this field is that 'skb_copy_datagram_iter()' handles both types of skb internally - it just needs an offset from which to copy data from the given skb. This offset is incremented on each read from skb. This approach allows to simplify handling of both linear and non-linear skbs, because for linear skb we need to call 'skb_pull()' after reading data from it, while in non-linear case we need to update 'data_len'. Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.