Re: [PATCHv5 bluetooth-next 0/3] 6lowpan: introduce nhc framework

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Hi Alex,

On pe, 2015-01-09 at 16:42 +0100, Alexander Aring wrote:
> This patch series introduce the next header compression framework. Currently
> we support udp compression/uncompression only. This framework allow to add new
> next header compression formats easily.
> 
> If somebody wants to add a new header compression format and some information
> are missing while calling compression and uncompression callbacks. Please
> feel free to make framework changes according these callbacks.
> 
> changes since v2:
>  - make udp nhc as module as suggested by Marcel Holtmann
>  - fix comment header in nhc_udp.c
> 
> I didn't make the lowpan_nhc declaration "const" because this will occur
> issues with rb_node, id and idmask array. Which will manipulated during
> runtime.
> 
> changes since v3:
>  - add patch 3/3 for other known rfc6282 ipv6 extension headers compression
>    formats
>  - add request_modules for loading nhc default compression format modules.
>    Which was suggested by Jukka Rissanen. Thanks, this is really working.
>  - Add rtnl_lock for lowpan_nhc_add and del since we have no synced
>    request_modules call this could make trouble.
>  - Move some handling out of nhc_do_compression and uncompression function.
>    The complete handling is now inside of iphc.c and nhc_do_compression and
>    uncompression functions is only a wrapper call for the callback.
>  - rework some menuentries for Kconfig and compression format, they are
>    grouped by rfc now.
>  - move some generic handling like "skb_pull(skb, nhc->nexthdrlen);" into
>    iphc.c. It would be great if we have something also for uncompression
>    for the skb_cow. But this isn't possible right now.
>  - change warning if nhc was not found to "was not found" instead isn't
>    implemented. It isn't implemented if callbacks are NULL now.
>  - small cleanups.
> 
> changes since v4:
>  - add spinlock for to prevent nhc from deletion while using. This can occur
>    if nhc module is unloading while compression/uncompression.
>  - move nhc handling for nhc compression/uncompression completely into
>    nhc_do_compression/nhc_do_uncompression.
> 
> Note about locking:
> 
> We have now a spinlock nhc_lowpan_lock which prevents manipulating the nhc
> datastructures while using it. On receiving side it's easy to handle, at the
> end we check if 6lowpan nh compressed flag is set and run uncompression.
> On the other hand the transmit side is complicated, we check if next_hdr field
> is registrated and run some other compression routines, at least we do the
> finally nhc compression which depends on the first check if next_hdr was
> registrated. The kernel will crash if we remove the using module between
> "next_hdr check" and "do nhc compression", the lock will prevent that now.
> 
> Now in the transmit path exist a little window to remove a lowpan_nhc while
> compression. This is exactly the part between "check if we support" and
> "doing compression". This is a very unlikely case, if this occurs we drop
> the packet while compression. Don't know how to better deal with that right
> now. I will try to search a better solution later.
> 
> changes since v5:
>  - s/rfc6282// on filenames and kconfig entries, suggested by Marcel Holtmann
>    and Stefan Schmidt
>  - s/FRAG/FRAGMENT/ - suggested by Stefan Schmidt
>  - s/MOBIL/MOBILITY/ - suggested by Stefan Schmidt
>  - s/ROUTE/ROUTING/ - suggested by Stefan Schmidt
>  - replace "depends on 6LOWPAN_NHC" with a global "if 6LOWPAN_NHC
>    $LOT_OF_ENTRIES endif" inside net/6lowpan/Kconfig
>  - fix small typo "nhc" -> "nhcs" in net/6lowpan/Makefile
>  - add MODULE_DESCRIPTION to each NHC module
> 
> Cc: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx>
> Cc: Martin Townsend <mtownsend1973@xxxxxxxxx>
> Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> Cc: Stefan Schmidt <s.schmidt@xxxxxxxxxxx>
> 
> Alexander Aring (3):
>   6lowpan: add generic nhc layer interface
>   6lowpan: add udp compression via nhc layer
>   6lowpan: nhc: add other known rfc6282 compressions
> 
>  net/6lowpan/Kconfig        |  57 ++++++++++-
>  net/6lowpan/Makefile       |  13 ++-
>  net/6lowpan/iphc.c         | 200 ++++++-------------------------------
>  net/6lowpan/nhc.c          | 241 +++++++++++++++++++++++++++++++++++++++++++++
>  net/6lowpan/nhc.h          | 146 +++++++++++++++++++++++++++
>  net/6lowpan/nhc_dest.c     |  28 ++++++
>  net/6lowpan/nhc_fragment.c |  27 +++++
>  net/6lowpan/nhc_hop.c      |  27 +++++
>  net/6lowpan/nhc_ipv6.c     |  27 +++++
>  net/6lowpan/nhc_mobility.c |  27 +++++
>  net/6lowpan/nhc_routing.c  |  27 +++++
>  net/6lowpan/nhc_udp.c      | 157 +++++++++++++++++++++++++++++
>  12 files changed, 806 insertions(+), 171 deletions(-)
>  create mode 100644 net/6lowpan/nhc.c
>  create mode 100644 net/6lowpan/nhc.h
>  create mode 100644 net/6lowpan/nhc_dest.c
>  create mode 100644 net/6lowpan/nhc_fragment.c
>  create mode 100644 net/6lowpan/nhc_hop.c
>  create mode 100644 net/6lowpan/nhc_ipv6.c
>  create mode 100644 net/6lowpan/nhc_mobility.c
>  create mode 100644 net/6lowpan/nhc_routing.c
>  create mode 100644 net/6lowpan/nhc_udp.c
> 


Acked-by: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx>


Cheers,
Jukka



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