[dpdk-dev] [PATCH 00/10] Improve cast alignment for strict aligned machines

Cyril Chemparathy cchemparathy at ezchip.com
Wed Apr 29 18:15:24 CEST 2015


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.

Cyril Chemparathy (10):
  eal: add and use unaligned integer types
  mempool: silence -Wcast-align on pointer arithmetic
  hash: silence -Wcast-align on pointer arithmetic
  mbuf: silence -Wcast-align on pointer arithmetic
  ethdev: silence -Wcast-align on pointer arithmetic
  app/test-pmd: pack simple_gre_hdr
  app/test: use struct ether_addr instead of a byte array cast
  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/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_mbuf.c                       | 16 +++----
 app/test/test_pmd_perf.c                   | 10 ++--
 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                 | 28 +++++++----
 lib/librte_mempool/rte_mempool.h           |  4 +-
 lib/librte_pmd_mlx4/mlx4.c                 |  9 ++--
 lib/librte_port/rte_port_ras.c             |  3 +-
 lib/librte_vhost/vhost_rxtx.c              |  4 +-
 scripts/cocci.sh                           | 64 +++++++++++++++++++++++++
 scripts/cocci/mtod-offset.cocci            | 76 ++++++++++++++++++++++++++++++
 29 files changed, 298 insertions(+), 144 deletions(-)
 create mode 100755 scripts/cocci.sh
 create mode 100644 scripts/cocci/mtod-offset.cocci

-- 
2.1.2



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