Re: [Qemu-devel] [PATCH v2 3/3] xen: call qemu_set_cloexec instead of fcntl

[Greg Kurz <groug@kaod.org>]

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On Tue,  9 May 2017 12:04:53 -0700
Stefano Stabellini <sstabellini@kernel.org> wrote:

> Use the common utility function, which contains checks on return values,

... and first calls F_GETFD as recommended by POSIX.1-2001.

http://pubs.opengroup.org/onlinepubs/009695399/functions/fcntl.html

"The arg values to F_GETFD, F_SETFD, F_GETFL, and F_SETFL all represent
flag values to allow for future growth. Applications using these functions
should do a read-modify-write operation on them, rather than assuming that
only the values defined by this volume of IEEE Std 1003.1-2001 are valid.
It is a common error to forget this, particularly in the case of F_SETFD."

> instead of manually calling fcntl.
> 
> CID: 1374831
> 
> Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
> CC: anthony.perard@citrix.com
> CC: groug@kaod.org
> CC: aneesh.kumar@linux.vnet.ibm.com
> CC: Eric Blake <eblake@redhat.com>
> ---
>  hw/9pfs/xen-9p-backend.c | 2 +-
>  hw/xen/xen_backend.c     | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 

Anyway,

Reviewed-by: Greg Kurz <groug@kaod.org>

> diff --git a/hw/9pfs/xen-9p-backend.c b/hw/9pfs/xen-9p-backend.c
> index a1fdede..5df97c9 100644
> --- a/hw/9pfs/xen-9p-backend.c
> +++ b/hw/9pfs/xen-9p-backend.c
> @@ -380,7 +380,7 @@ static int xen_9pfs_connect(struct XenDevice *xendev)
>          if (xen_9pdev->rings[i].evtchndev == NULL) {
>              goto out;
>          }
> -        fcntl(xenevtchn_fd(xen_9pdev->rings[i].evtchndev), F_SETFD,
> FD_CLOEXEC);
> +        qemu_set_cloexec(xenevtchn_fd(xen_9pdev->rings[i].evtchndev));
>          xen_9pdev->rings[i].local_port = xenevtchn_bind_interdomain
>                                              (xen_9pdev->rings[i].evtchndev,
>                                               xendev->dom,
> diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
> index c85f163..2cac47d 100644
> --- a/hw/xen/xen_backend.c
> +++ b/hw/xen/xen_backend.c
> @@ -147,7 +147,7 @@ static struct XenDevice *xen_be_get_xendev(const char
> *type, int dom, int dev, qdev_unplug(DEVICE(xendev), NULL);
>          return NULL;
>      }
> -    fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> +    qemu_set_cloexec(xenevtchn_fd(xendev->evtchndev));
>  
>      if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
>          xendev->gnttabdev = xengnttab_open(NULL, 0);


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