This patch adds the necessary handling for the physical device driver to
use multiple pages to hold data in the SKBs. Essentially, the following
changes are implemented:
- rmnet_frag_descriptor struct now hold a list of frags, instead of a
single one. Pushing, pulling, and trimming APIs are updated to use
this new format.
- QMAP deaggregation now loops over each element in skb_shinfo->frags
looking for data. Packets are allowed to be split across mutliple
pages. All pages containing data for a particular packet will be added
to the frag_descriptor struct representing it.
- a new API, rmnet_frag_header_ptr() has been added for safely accessing
packet headers. This API, modeled after skb_header_pointer(), handles
the fact that headers could potentially be split across 2 pages. A
pointer to the location of the header is returned in the usual case
where the header is physically contiguous. If not, the header is
linearized into the user-provided buffer to allow normal header struct
read access.
- this new header access API is used in all places on the DL path when
headers are needed, including QMAP command processing, QMAPv1
handling, QMAPv5 checksum offload, and QMAPv5 coalescing.
- RSB/RSC segmentation handling is updated to add all necessary pages
containing packet data to the newly created descriptor. Additionally,
the pages containing L3 and L4 headers are added as well, as this
allows easier downstream processing, and guarantees that the header
data will not be freed until all packets that need them have been
converted into SKBs.
- as all frag_descriptors are now guaranteed to contain the L3 and L4
header data (and because they are no longer guaranteed to be on the
same page), the hdr_ptr member has been removed as it no longer serves
a purpose.
Change-Id: Iebb677a6ae7e442fa55e0d131af59cde1b5ce18a
Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
06bf42ec24