Re: [dpdk-dev] [PATCH 1/3] ring: fix build for gcc O1 optimization

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> 
> Can be reproduced with "make EXTRA_CFLAGS='-O1'" command using
> gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2)
> 
> Two build errors:
> 1)
> In file included from .../build/include/rte_ring_elem.h:1093,
>                  from .../lib/librte_rcu/rte_rcu_qsbr.c:21:
> ../lib/librte_rcu/rte_rcu_qsbr.c: In function ‘rte_rcu_qsbr_dq_reclaim’:
> .../build/include/rte_ring_peek.h:282:22:
>     error: ‘avail’ may be used uninitialized in this function
>            [-Werror=maybe-uninitialized]
>   282 |   *available = avail - n;
>       |                ~~~~~~^~~
> ./build/include/rte_ring_peek.h:259:11: note: ‘avail’ was declared here
>   259 |  uint32_t avail, head, next;
>       |           ^~~~~
> 
> 2)
> In file included from .../build/include/rte_ring_elem.h:1093,
>                  from .../build/include/rte_ring.h:405,
>                  from .../app/test/test_ring_stress.h:13,
>                  from .../app/test/test_ring_stress_impl.h:5,
>                  from .../app/test/test_ring_peek_stress.c:5:
> .../app/test/test_ring_peek_stress.c: In function ‘_st_ring_enqueue_bulk’:
> .../build/include/rte_ring_peek.h:80:22:
>     error: ‘free’ may be used uninitialized in this function
>            [-Werror=maybe-uninitialized]
>    80 |   *free_space = free - n;
>       |                 ~~~~~^~~
> .../build/include/rte_ring_peek.h:60:11: note: ‘free’ was declared here
>    60 |  uint32_t free, head, next;
>       |           ^~~~
> 
> The cases shouldn't be hit, and it looks like there is already logic
> error if it has been hit, but assigning 'avail' & 'free' to '0' to fix
> the build error.
> 
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> ---
>  lib/librte_ring/rte_ring_peek.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/lib/librte_ring/rte_ring_peek.h b/lib/librte_ring/rte_ring_peek.h
> index d5e6ea1cf3..45f707dc7e 100644
> --- a/lib/librte_ring/rte_ring_peek.h
> +++ b/lib/librte_ring/rte_ring_peek.h
> @@ -74,6 +74,7 @@ __rte_ring_do_enqueue_start(struct rte_ring *r, uint32_t n,
>  		/* unsupported mode, shouldn't be here */
>  		RTE_ASSERT(0);
>  		n = 0;
> +		free = 0;
>  	}
> 
>  	if (free_space != NULL)
> @@ -273,6 +274,7 @@ __rte_ring_do_dequeue_start(struct rte_ring *r, void *obj_table,
>  		/* unsupported mode, shouldn't be here */
>  		RTE_ASSERT(0);
>  		n = 0;
> +		avail = 0;
>  	}
> 
>  	if (n != 0)
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.25.4