[CRIU] [PATCH] lazy-pages: consolidate error handling for uffdio_copy and uffdio_zeropage

[Andrei Vagin]

On Fri, Sep 22, 2017 at 06:25:43PM +0300, Mike Rapoport wrote:
> The errors set by both uffdio_copy and uffdio_zeropage are the same and
> require the same handling. Let's use a helper function to handle the errors
> returned by uffdio_copy and uffdio_zero.
> 
> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
> ---
> 
> The patch is agaist criu-dev but should apply to master just the same
> 
>  criu/uffd.c | 40 +++++++++++++++++++++++-----------------
>  1 file changed, 23 insertions(+), 17 deletions(-)
> 
> diff --git a/criu/uffd.c b/criu/uffd.c
> index 43dc0ce..22b65ce 100644
> --- a/criu/uffd.c
> +++ b/criu/uffd.c
> @@ -705,6 +705,27 @@ static int handle_exit(struct lazy_pages_info *lpi)
>  	return 0;
>  }
>  
> +static int uffd_check_op_error(struct lazy_pages_info *lpi, const char *op,
> +			       unsigned long len, unsigned long rc_len, int rc)
> +{
> +	if (rc) {
> +		if (errno == ENOSPC || errno == ESRCH) {
> +			handle_exit(lpi);
> +			return 0;
> +		}
> +		if (rc_len != -EEXIST) {
> +			lp_debug(lpi, "%s: rc:%d copy:%ld, errno:%d\n",
> +				 op, rc, rc_len, errno);

Why do we use lp_debug instead of lp_perror?


> +			return -1;
> +		}
> +	} else if (rc_len != len) {
> +		lp_err(lpi, "%s unexpected size %ld\n", op, rc_len);
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
>  static int uffd_copy(struct lazy_pages_info *lpi, __u64 address, int nr_pages)
>  {
>  	struct uffdio_copy uffdio_copy;
> @@ -719,20 +740,8 @@ static int uffd_copy(struct lazy_pages_info *lpi, __u64 address, int nr_pages)
>  
>  	lp_debug(lpi, "uffd_copy: 0x%llx/%ld\n", uffdio_copy.dst, len);
>  	rc = ioctl(lpi->lpfd.fd, UFFDIO_COPY, &uffdio_copy);
> -	if (rc) {
> -		if (errno == ENOSPC || errno == ESRCH) {
> -			handle_exit(lpi);
> -			return 0;
> -		}
> -		if (uffdio_copy.copy != -EEXIST) {
> -			lp_debug(lpi, "uffd_copy: rc:%d copy:%Ld, errno:%d\n",
> -				 rc, uffdio_copy.copy, errno);
> -			return -1;
> -		}
> -	} else if (uffdio_copy.copy != len) {
> -		lp_err(lpi, "UFFDIO_COPY unexpected size %Ld\n", uffdio_copy.copy);
> +	if (uffd_check_op_error(lpi, "copy", len, uffdio_copy.copy, rc))
>  		return -1;
> -	}
>  
>  	lpi->copied_pages += nr_pages;
>  
> @@ -784,11 +793,8 @@ static int uffd_zero(struct lazy_pages_info *lpi, __u64 address, int nr_pages)
>  
>  	lp_debug(lpi, "zero page at 0x%llx\n", address);
>  	rc = ioctl(lpi->lpfd.fd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
> -	if (rc) {
> -		lp_perror(lpi, "zero page failed: %Ld",
> -			  uffdio_zeropage.zeropage);
> +	if (uffd_check_op_error(lpi, "zero", len, uffdio_zeropage.zeropage, rc))
>  		return -1;
> -	}
>  
>  	return 0;
>  }
> -- 
> 2.7.4
>