Re: [dpdk-dev] [PATCH v4 0/9] Improve cast alignment for strict aligned machines

[Olivier MATZ <olivier.matz@6wind.com>]

Hi Cyril,

On 06/22/2015 08:34 PM, Cyril Chemparathy wrote:
> This series contains a few improvements that allow the DPDK code base
> to build properly on machines that enforce strict pointer cast
> alignment constraints.
>
> When dealing with packet data which could be arbitrarily aligned, we
> get the compiler to do the right thing by (a) making sure that header
> types are packed, and (b) introducing and using
> unaligned_uint(16|32|64)_t types when upcasting from byte pointers.
>
> In a few other instances, we know apriori that the pointer cast cannot
> possibly break alignment.  This applies to the changes in mempool,
> hash, mbuf, and the ethdev stats code.  Here, we simply silence the
> compiler by casting through (void *) using the RTE_PTR_(ADD|SUB)
> macros.
>
> Finally, we introduce a new rte_pktmbuf_mtod_offset() helper to return
> a type casted pointer to an offset within the packet data.  This
> replaces the following commonly used pattern:
> 	(struct foo *)(rte_pktmbuf_mtod(m, char *) + offset)
> with:
> 	rte_pktmbuf_mtod_offset(m, struct foo *, offset)
>
> To ensure consistency, the above transform was applied throughout the
> code base using the coccinelle semantic patching tool.

Series
Acked-by: Olivier Matz <olivier.matz@6wind.com>



>
> Changes in this series:
>    v2: Fixes based on Olivier's comments.
>    v3: Extends unaligned fixes to new code introduced on master.
>    v4: Fixes based on Thomas' comments.
>        Extends unaligned fixes to new code introduced on master.
>
> Cyril Chemparathy (9):
>    mempool: silence -Wcast-align on pointer arithmetic
>    mbuf: silence -Wcast-align on pointer arithmetic
>    ethdev: silence -Wcast-align on pointer arithmetic
>    hash: silence -Wcast-align on pointer arithmetic
>    eal: add and use unaligned integer types
>    app/test-pmd: pack simple_gre_hdr
>    librte_mbuf: Add rte_pktmbuf_mtod_offset()
>    librte_mbuf: Add transform for rte_pktmbuf_mtod_offset()
>    librte_mbuf: Apply mtod-offset.cocci transform
>
>   app/test-pmd/csumonly.c                    |  2 +-
>   app/test-pmd/flowgen.c                     |  4 +-
>   app/test-pmd/icmpecho.c                    |  2 +-
>   app/test-pmd/ieee1588fwd.c                 |  4 +-
>   app/test-pmd/rxonly.c                      | 21 +++++----
>   app/test-pmd/txonly.c                      |  6 +--
>   app/test/packet_burst_generator.c          |  9 ++--
>   app/test/test_hash_functions.c             |  2 +-
>   app/test/test_mbuf.c                       | 16 +++----
>   config/common_bsdapp                       |  5 ++
>   config/common_linuxapp                     |  5 ++
>   drivers/net/bonding/rte_eth_bond_pmd.c     | 12 +++--
>   drivers/net/mlx4/mlx4.c                    |  9 ++--
>   examples/dpdk_qat/crypto.c                 |  8 ++--
>   examples/dpdk_qat/main.c                   |  5 +-
>   examples/l3fwd-acl/main.c                  | 20 ++++----
>   examples/l3fwd-power/main.c                |  8 ++--
>   examples/l3fwd-vf/main.c                   |  4 +-
>   examples/l3fwd/main.c                      | 71 ++++++++++++----------------
>   examples/load_balancer/runtime.c           |  4 +-
>   examples/vhost_xen/main.c                  |  4 +-
>   lib/librte_eal/common/include/rte_common.h | 10 ++++
>   lib/librte_ether/rte_ethdev.c              | 24 +++++-----
>   lib/librte_ether/rte_ether.h               |  2 +-
>   lib/librte_hash/rte_hash.c                 | 10 ++--
>   lib/librte_ip_frag/rte_ipv4_reassembly.c   |  7 ++-
>   lib/librte_ip_frag/rte_ipv6_reassembly.c   |  5 +-
>   lib/librte_mbuf/rte_mbuf.h                 | 32 +++++++++----
>   lib/librte_mempool/rte_mempool.c           |  2 +-
>   lib/librte_mempool/rte_mempool.h           |  6 +--
>   lib/librte_port/rte_port_ras.c             |  6 +--
>   lib/librte_vhost/vhost_rxtx.c              |  6 +--
>   scripts/cocci.sh                           | 64 +++++++++++++++++++++++++
>   scripts/cocci/mtod-offset.cocci            | 76 ++++++++++++++++++++++++++++++
>   34 files changed, 319 insertions(+), 152 deletions(-)
>   create mode 100755 scripts/cocci.sh
>   create mode 100644 scripts/cocci/mtod-offset.cocci
>