Re: [Qemu-devel] [PATCH] net: Add persistent flag to -net tap option

[Eric Blake]

On 12/21/2014 12:48 AM, Roy Vardi wrote:
> From: Roy Vardi <address@hidden>
> 
>     Add 'persistent' boolean flag to -net tap option.
>     When set to off - tap interface will be released on shutdown
>     When set to on\not specified - tap interface will remain
> 
>     Running with -net tap,persistent=off will force the tap interface
>     down when qemu goes down, thus ensuring that there're no zombie tap

s/there're/there are/

>     interfaces left
> 
>     This is achieved using another ioctl
> 
>     Note: This commit includes the above support only for linux systems
> 
> Signed-off-by: Roy Vardi <address@hidden>
> ---
>  #define PATH_NET_TUN "/dev/net/tun"
>  
>  int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
> -             int vnet_hdr_required, int mq_required)
> +             int vnet_hdr_required, int mq_required, int persistent_required)

Used as a boolean, so s/int/bool/

>  {
>      struct ifreq ifr;
>      int fd, ret;
> @@ -109,6 +110,17 @@ int tap_open(char *ifname, int ifname_size, int 
> *vnet_hdr,
>          close(fd);
>          return -1;
>      }
> +
> +    if (!persistent_required) {
> +        ret = ioctl(fd, TUNSETPERSIST, 0);
> +        if (ret != 0) {
> +            error_report("could not configure non-persistent %s (%s): %m",

%m is not portable to non-glibc (then again, this file is Linux-only).


> +++ b/net/tap.c
> @@ -556,7 +556,8 @@ int net_init_bridge(const NetClientOptions *opts, const 
> char *name,
>  
>  static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
>                          const char *setup_script, char *ifname,
> -                        size_t ifname_sz, int mq_required)
> +                        size_t ifname_sz, int mq_required,
> +                        int persistent_required)

Again, prefer bool.


> @@ -688,7 +689,7 @@ int net_init_tap(const NetClientOptions *opts, const char 
> *name,
>                   NetClientState *peer)
>  {
>      const NetdevTapOptions *tap;
> -    int fd, vnet_hdr = 0, i = 0, queues;
> +    int fd, vnet_hdr = 0, i = 0, queues, persistent;

Use bool.

>      /* for the no-fd, no-helper case */
>      const char *script = NULL; /* suppress wrong "uninit'd use" gcc warning 
> */
>      const char *downscript = NULL;
> @@ -699,6 +700,7 @@ int net_init_tap(const NetClientOptions *opts, const char 
> *name,
>      tap = opts->tap;
>      queues = tap->has_queues ? tap->queues : 1;
>      vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
> +    persistent = tap->has_persistent ? tap->persistent : 1;

s/1/true/


> +++ b/qapi-schema.json
> @@ -2007,6 +2007,8 @@
>  #
>  # @queues: #optional number of queues to be created for multiqueue capable 
> tap
>  #
> +# @persistent: #optional for opening tap in persistent mode (default: on) 
> (Since: 2.3)

Long line; please wrap at 80 columns.  In QMP, the default is 'true',
not 'on' (the command line parser maps multiple strings including 'on'
into the single QMP bool type).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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