Re: [PATCH] softmmu/device_tree: Silence compiler warning with --enable-sanitizers

[Andrew Jones]

On Fri, Jan 07, 2022 at 02:38:44PM +0100, Thomas Huth wrote:
> If I configure my build with --enable-sanitizers, my GCC (v8.5.0)
> complains:
> 
> .../softmmu/device_tree.c: In function ‘qemu_fdt_add_path’:
> .../softmmu/device_tree.c:560:18: error: ‘retval’ may be used uninitialized
>  in this function [-Werror=maybe-uninitialized]
>      int namelen, retval;
>                   ^~~~~~
> 
> It's a false warning since the while loop is always executed at least
> once (p has to be non-NULL, otherwise the derefence in the if-statement
> earlier will crash). Thus let's switch to a do-while loop here instead
> to make the compiler happy in all cases.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  softmmu/device_tree.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
> index 3965c834ca..9e96f5ecd5 100644
> --- a/softmmu/device_tree.c
> +++ b/softmmu/device_tree.c
> @@ -564,7 +564,7 @@ int qemu_fdt_add_path(void *fdt, const char *path)
>          return -1;
>      }
>  
> -    while (p) {
> +    do {
>          name = p + 1;
>          p = strchr(name, '/');
>          namelen = p != NULL ? p - name : strlen(name);
> @@ -584,7 +584,7 @@ int qemu_fdt_add_path(void *fdt, const char *path)
>          }
>  
>          parent = retval;
> -    }
> +    } while (p);
>  
>      return retval;
>  }
> -- 
> 2.27.0
>

 
Reviewed-by: Andrew Jones <drjones@redhat.com>