linux-kernel - Re: [PATCH 15/29] selftests/mm: uffd_open

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Date:   Fri, 7 Apr 2023 14:11:37 +0300
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nadav Amit <nadav.amit@...il.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Leonardo Bras Soares Passos <lsoaresp@...hat.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>
Subject: Re: [PATCH 15/29] selftests/mm: uffd_open_{dev|sys}()

On Thu, Mar 30, 2023 at 12:07:49PM -0400, Peter Xu wrote:
> Provide two helpers to open an uffd handle.  Drop the error checks around
> SKIPs because it's inside an errexit() anyway, which IMHO doesn't really
> help much if the test will not continue.
> 
> Signed-off-by: Peter Xu <peterx@...hat.com>

Reviewed-by: Mike Rapoport (IBM) <rppt@...nel.org>

> ---
>  tools/testing/selftests/mm/uffd-common.c | 28 +++++-------------------
>  tools/testing/selftests/mm/vm_util.c     | 24 ++++++++++++++++++++
>  2 files changed, 29 insertions(+), 23 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c
> index 17f2bb82c3db..3a9b5c1aca9d 100644
> --- a/tools/testing/selftests/mm/uffd-common.c
> +++ b/tools/testing/selftests/mm/uffd-common.c
> @@ -192,34 +192,16 @@ void uffd_stats_report(struct uffd_stats *stats, int n_cpus)
>  	printf("\n");
>  }
> 
> -static int __userfaultfd_open_dev(void)
> -{
> -	int fd, _uffd;
> -
> -	fd = open("/dev/userfaultfd", O_RDWR | O_CLOEXEC);
> -	if (fd < 0)
> -		errexit(KSFT_SKIP, "opening /dev/userfaultfd failed");
> -
> -	_uffd = ioctl(fd, USERFAULTFD_IOC_NEW, UFFD_FLAGS);
> -	if (_uffd < 0)
> -		errexit(errno == ENOTTY ? KSFT_SKIP : 1,
> -			"creating userfaultfd failed");
> -	close(fd);
> -	return _uffd;
> -}
> -
>  void userfaultfd_open(uint64_t *features)
>  {
>  	struct uffdio_api uffdio_api;
> 
>  	if (test_dev_userfaultfd)
> -		uffd = __userfaultfd_open_dev();
> -	else {
> -		uffd = syscall(__NR_userfaultfd, UFFD_FLAGS);
> -		if (uffd < 0)
> -			errexit(errno == ENOSYS ? KSFT_SKIP : 1,
> -				"creating userfaultfd failed");
> -	}
> +		uffd = uffd_open_dev(UFFD_FLAGS);
> +	else
> +		uffd = uffd_open_sys(UFFD_FLAGS);
> +	if (uffd < 0)
> +		err("uffd open failed (dev=%d)", test_dev_userfaultfd);
>  	uffd_flags = fcntl(uffd, F_GETFD, NULL);
> 
>  	uffdio_api.api = UFFD_API;
> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> index 10e76400ed70..7c2bf88d6393 100644
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -3,6 +3,8 @@
>  #include <fcntl.h>
>  #include <sys/ioctl.h>
>  #include <linux/userfaultfd.h>
> +#include <sys/syscall.h>
> +#include <unistd.h>
>  #include "../kselftest.h"
>  #include "vm_util.h"
> 
> @@ -230,3 +232,25 @@ int uffd_unregister(int uffd, void *addr, uint64_t len)
> 
>  	return ret;
>  }
> +
> +int uffd_open_dev(unsigned int flags)
> +{
> +	int fd, uffd;
> +
> +	fd = open("/dev/userfaultfd", O_RDWR | O_CLOEXEC);
> +	if (fd < 0)
> +		return fd;
> +	uffd = ioctl(fd, USERFAULTFD_IOC_NEW, flags);
> +	close(fd);
> +
> +	return uffd;
> +}
> +
> +int uffd_open_sys(unsigned int flags)
> +{
> +#ifdef __NR_userfaultfd
> +	return syscall(__NR_userfaultfd, flags);
> +#else
> +	return -1;
> +#endif
> +}
> -- 
> 2.39.1
> 

-- 
Sincerely yours,
Mike.