RE: [PATCH v5 6/6] ring: use inline instead of always inline in soring

[Konstantin Ananyev <konstantin.ananyev@huawei.com>]

> 
> When LTO is enabled, GCC inlines through the entire soring call chain
> from test code into the ring element copy functions. With always_inline,
> the compiler is forced to inline __rte_ring_dequeue_elems_128() which
> copies 32 bytes per element. GCC's static analysis then warns about
> potential buffer overflow because it cannot prove the 128-bit element
> path is unreachable when the ring is configured for 4-byte elements:
> 
>   warning: writing 32 bytes into a region of size 0 [-Wstringop-overflow=]
> 
> By using plain inline instead of always_inline on the soring enqueue
> and dequeue functions, the compiler regains discretion over inlining
> decisions. This introduces an analysis boundary that prevents GCC from
> connecting the test's buffer sizes to the unreachable 128-bit code path,
> eliminating the false positive warning.
> 
> Performance impact is expected to be negligible. At -O2/-O3, the
> compiler will still inline these small, hot functions based on its
> own heuristics. The difference only matters in debug builds or with
> -Os, where slightly less aggressive inlining is acceptable.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/ring/soring.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/ring/soring.c b/lib/ring/soring.c
> index 797484d6bf..3b90521bdb 100644
> --- a/lib/ring/soring.c
> +++ b/lib/ring/soring.c
> @@ -249,7 +249,7 @@ __rte_soring_stage_move_head(struct
> soring_stage_headtail *d,
>  	return n;
>  }
> 
> -static __rte_always_inline uint32_t
> +static inline uint32_t
>  soring_enqueue(struct rte_soring *r, const void *objs,
>  	const void *meta, uint32_t n, enum rte_ring_queue_behavior behavior,
>  	uint32_t *free_space)
> @@ -278,7 +278,7 @@ soring_enqueue(struct rte_soring *r, const void *objs,
>  	return n;
>  }
> 
> -static __rte_always_inline uint32_t
> +static inline uint32_t
>  soring_dequeue(struct rte_soring *r, void *objs, void *meta,
>  	uint32_t num, enum rte_ring_queue_behavior behavior,
>  	uint32_t *available)
> --

Run quick test, no perf degradation noticed.
Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
Tested-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
 
> 2.51.0