Re: [PATCH] selftests/powerpc: use MAP_FAILED instead of (void *)-1 in tm-signal-context-force-tm

[Amit Machhiwal <amachhiw@linux.ibm.com>]

On 2026/07/22 10:34 AM, longlong yan wrote:
> mmap() is documented to return MAP_FAILED on error, but
> tm-signal-context-force-tm.c compares the return value against
> (void *)-1. Replace these with the standard MAP_FAILED macro for
> better readability and type safety.

The mmap man page does confirm:

  RETURN VALUE
         On success, mmap() returns a pointer to the mapped area.  On
         error, the value MAP_FAILED (that is, (void *) -1) is returned,
         and errno is set to indicate the error.

So, the MAP_FAILED substitution looks correct. Please feel free to add:

Reviewed-by: Amit Machhiwal <amachhiw@linux.ibm.com>

Thanks,
Amit

> 
> Signed-off-by: longlong yan <yanlonglong@kylinos.cn>
> ---
>  .../testing/selftests/powerpc/tm/tm-signal-context-force-tm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c b/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c
> index 0a4bc479ae39..5dc0f12f467d 100644
> --- a/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c
> +++ b/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c
> @@ -60,7 +60,7 @@ void usr_signal_handler(int signo, siginfo_t *si, void *uc)
>  	ucp->uc_link = mmap(NULL, sizeof(ucontext_t),
>  			    PROT_READ | PROT_WRITE,
>  			    MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
> -	if (ucp->uc_link == (void *)-1) {
> +	if (ucp->uc_link == MAP_FAILED) {
>  		perror("Mmap failed");
>  		exit(-1);
>  	}
> @@ -129,7 +129,7 @@ void tm_trap_test(void)
>  		ss.ss_size = SIGSTKSZ;
>  		ss.ss_flags = 0;
>  
> -		if (ss.ss_sp == (void *)-1) {
> +		if (ss.ss_sp == MAP_FAILED) {
>  			perror("mmap error\n");
>  			exit(-1);
>  		}
> -- 
> 2.43.0
>