[v6,18/39] reorder: use C11 alignas

Message ID 1708971946-18231-19-git-send-email-roretzla@linux.microsoft.com (mailing list archive)
State Superseded, archived
Delegated to: Thomas Monjalon
Series use C11 alignas |


Context Check Description
ci/checkpatch success coding style OK

Commit Message

Tyler Retzlaff Feb. 26, 2024, 6:25 p.m. UTC
  The current location used for __rte_aligned(a) for alignment of types
and variables is not compatible with MSVC. There is only a single
location accepted by both toolchains.

For variables standard C11 offers alignas(a) supported by conformant
compilers i.e. both MSVC and GCC.

For types the standard offers no alignment facility that compatibly
interoperates with C and C++ but may be achieved by relocating the
placement of __rte_aligned(a) to the aforementioned location accepted
by all currently supported toolchains.

To allow alignment for both compilers do the following:

* Move __rte_aligned from the end of {struct,union} definitions to
  be between {struct,union} and tag.

  The placement between {struct,union} and the tag allows the desired
  alignment to be imparted on the type regardless of the toolchain being
  used for all of GCC, LLVM, MSVC compilers building both C and C++.

* Replace use of __rte_aligned(a) on variables/fields with alignas(a).

Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
 lib/reorder/rte_reorder.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)


diff --git a/lib/reorder/rte_reorder.c b/lib/reorder/rte_reorder.c
index c080b2c..ae97e1a 100644
--- a/lib/reorder/rte_reorder.c
+++ b/lib/reorder/rte_reorder.c
@@ -37,16 +37,16 @@ 
 int rte_reorder_seqn_dynfield_offset = -1;
 /* A generic circular buffer */
-struct cir_buffer {
+struct __rte_cache_aligned cir_buffer {
 	unsigned int size;   /**< Number of entries that can be stored */
 	unsigned int mask;   /**< [buffer_size - 1]: used for wrap-around */
 	unsigned int head;   /**< insertion point in buffer */
 	unsigned int tail;   /**< extraction point in buffer */
 	struct rte_mbuf **entries;
-} __rte_cache_aligned;
 /* The reorder buffer data structure itself */
-struct rte_reorder_buffer {
+struct __rte_cache_aligned rte_reorder_buffer {
 	uint32_t min_seqn;  /**< Lowest seq. number that can be in the buffer */
 	unsigned int memsize; /**< memory area size of reorder buffer */
@@ -54,7 +54,7 @@  struct rte_reorder_buffer {
 	struct cir_buffer ready_buf; /**< temp buffer for dequeued entries */
 	struct cir_buffer order_buf; /**< buffer used to reorder entries */
-} __rte_cache_aligned;
 static void
 rte_reorder_free_mbufs(struct rte_reorder_buffer *b);