Re: [Qemu-devel] [PATCH v2] net: netmap: use nm_open() to open netmap ports

[Jason Wang]

On 01/26/2016 02:24 AM, Vincenzo Maffione wrote:
> This patch simplifies the netmap backend code by means of the nm_open()
> helper function provided by netmap_user.h, which hides the details of
> open(), iotcl() and mmap() carried out on the netmap device.
>
> Moreover, the semantic of nm_open() makes it possible to open special
> netmap ports (e.g. pipes, monitors) and use special modes (e.g. host rings
> only, single queue mode, exclusive access).
>
> Signed-off-by: Vincenzo Maffione <address@hidden>

Applied to -net.

Thanks

> ---
>  net/netmap.c | 97 
> ++++++++++++++++++++----------------------------------------
>  1 file changed, 32 insertions(+), 65 deletions(-)
>
> diff --git a/net/netmap.c b/net/netmap.c
> index 5558368..27295ab 100644
> --- a/net/netmap.c
> +++ b/net/netmap.c
> @@ -39,21 +39,12 @@
>  #include "qemu/error-report.h"
>  #include "qemu/iov.h"
>  
> -/* Private netmap device info. */
> -typedef struct NetmapPriv {
> -    int                 fd;
> -    size_t              memsize;
> -    void                *mem;
> -    struct netmap_if    *nifp;
> -    struct netmap_ring  *rx;
> -    struct netmap_ring  *tx;
> -    char                fdname[PATH_MAX];        /* Normally "/dev/netmap". 
> */
> -    char                ifname[IFNAMSIZ];
> -} NetmapPriv;
> -
>  typedef struct NetmapState {
>      NetClientState      nc;
> -    NetmapPriv          me;
> +    struct nm_desc      *nmd;
> +    char                ifname[IFNAMSIZ];
> +    struct netmap_ring  *tx;
> +    struct netmap_ring  *rx;
>      bool                read_poll;
>      bool                write_poll;
>      struct iovec        iov[IOV_MAX];
> @@ -90,44 +81,23 @@ pkt_copy(const void *_src, void *_dst, int l)
>   * Open a netmap device. We assume there is only one queue
>   * (which is the case for the VALE bridge).
>   */
> -static void netmap_open(NetmapPriv *me, Error **errp)
> +static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
> +                                   Error **errp)
>  {
> -    int fd;
> -    int err;
> -    size_t l;
> +    struct nm_desc *nmd;
>      struct nmreq req;
>  
> -    me->fd = fd = open(me->fdname, O_RDWR);
> -    if (fd < 0) {
> -        error_setg_file_open(errp, errno, me->fdname);
> -        return;
> -    }
>      memset(&req, 0, sizeof(req));
> -    pstrcpy(req.nr_name, sizeof(req.nr_name), me->ifname);
> -    req.nr_ringid = NETMAP_NO_TX_POLL;
> -    req.nr_version = NETMAP_API;
> -    err = ioctl(fd, NIOCREGIF, &req);
> -    if (err) {
> -        error_setg_errno(errp, errno, "Unable to register %s", me->ifname);
> -        goto error;
> -    }
> -    l = me->memsize = req.nr_memsize;
>  
> -    me->mem = mmap(0, l, PROT_WRITE | PROT_READ, MAP_SHARED, fd, 0);
> -    if (me->mem == MAP_FAILED) {
> -        error_setg_errno(errp, errno, "Unable to mmap netmap shared memory");
> -        me->mem = NULL;
> -        goto error;
> +    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
> +                  NULL);
> +    if (nmd == NULL) {
> +        error_setg_errno(errp, errno, "Failed to nm_open() %s",
> +                         nm_opts->ifname);
> +        return NULL;
>      }
>  
> -    me->nifp = NETMAP_IF(me->mem, req.nr_offset);
> -    me->tx = NETMAP_TXRING(me->nifp, 0);
> -    me->rx = NETMAP_RXRING(me->nifp, 0);
> -
> -    return;
> -
> -error:
> -    close(me->fd);
> +    return nmd;
>  }
>  
>  static void netmap_send(void *opaque);
> @@ -136,7 +106,7 @@ static void netmap_writable(void *opaque);
>  /* Set the event-loop handlers for the netmap backend. */
>  static void netmap_update_fd_handler(NetmapState *s)
>  {
> -    qemu_set_fd_handler(s->me.fd,
> +    qemu_set_fd_handler(s->nmd->fd,
>                          s->read_poll ? netmap_send : NULL,
>                          s->write_poll ? netmap_writable : NULL,
>                          s);
> @@ -188,7 +158,7 @@ static ssize_t netmap_receive(NetClientState *nc,
>        const uint8_t *buf, size_t size)
>  {
>      NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
> -    struct netmap_ring *ring = s->me.tx;
> +    struct netmap_ring *ring = s->tx;
>      uint32_t i;
>      uint32_t idx;
>      uint8_t *dst;
> @@ -218,7 +188,7 @@ static ssize_t netmap_receive(NetClientState *nc,
>      ring->slot[i].flags = 0;
>      pkt_copy(buf, dst, size);
>      ring->cur = ring->head = nm_ring_next(ring, i);
> -    ioctl(s->me.fd, NIOCTXSYNC, NULL);
> +    ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
>  
>      return size;
>  }
> @@ -227,7 +197,7 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
>                      const struct iovec *iov, int iovcnt)
>  {
>      NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
> -    struct netmap_ring *ring = s->me.tx;
> +    struct netmap_ring *ring = s->tx;
>      uint32_t last;
>      uint32_t idx;
>      uint8_t *dst;
> @@ -284,7 +254,7 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
>      /* Now update ring->cur and ring->head. */
>      ring->cur = ring->head = i;
>  
> -    ioctl(s->me.fd, NIOCTXSYNC, NULL);
> +    ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
>  
>      return iov_size(iov, iovcnt);
>  }
> @@ -301,7 +271,7 @@ static void netmap_send_completed(NetClientState *nc, 
> ssize_t len)
>  static void netmap_send(void *opaque)
>  {
>      NetmapState *s = opaque;
> -    struct netmap_ring *ring = s->me.rx;
> +    struct netmap_ring *ring = s->rx;
>  
>      /* Keep sending while there are available packets into the netmap
>         RX ring and the forwarding path towards the peer is open. */
> @@ -349,10 +319,8 @@ static void netmap_cleanup(NetClientState *nc)
>      qemu_purge_queued_packets(nc);
>  
>      netmap_poll(nc, false);
> -    munmap(s->me.mem, s->me.memsize);
> -    close(s->me.fd);
> -
> -    s->me.fd = -1;
> +    nm_close(s->nmd);
> +    s->nmd = NULL;
>  }
>  
>  /* Offloading manipulation support callbacks. */
> @@ -383,17 +351,17 @@ static void netmap_set_vnet_hdr_len(NetClientState *nc, 
> int len)
>      struct nmreq req;
>  
>      /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header
> -     * length for the netmap adapter associated to 'me->ifname'.
> +     * length for the netmap adapter associated to 's->ifname'.
>       */
>      memset(&req, 0, sizeof(req));
> -    pstrcpy(req.nr_name, sizeof(req.nr_name), s->me.ifname);
> +    pstrcpy(req.nr_name, sizeof(req.nr_name), s->ifname);
>      req.nr_version = NETMAP_API;
>      req.nr_cmd = NETMAP_BDG_VNET_HDR;
>      req.nr_arg1 = len;
> -    err = ioctl(s->me.fd, NIOCREGIF, &req);
> +    err = ioctl(s->nmd->fd, NIOCREGIF, &req);
>      if (err) {
>          error_report("Unable to execute NETMAP_BDG_VNET_HDR on %s: %s",
> -                     s->me.ifname, strerror(errno));
> +                     s->ifname, strerror(errno));
>      } else {
>          /* Keep track of the current length. */
>          s->vnet_hdr_len = len;
> @@ -437,16 +405,12 @@ int net_init_netmap(const NetClientOptions *opts,
>                      const char *name, NetClientState *peer, Error **errp)
>  {
>      const NetdevNetmapOptions *netmap_opts = opts->u.netmap;
> +    struct nm_desc *nmd;
>      NetClientState *nc;
>      Error *err = NULL;
> -    NetmapPriv me;
>      NetmapState *s;
>  
> -    pstrcpy(me.fdname, sizeof(me.fdname),
> -        netmap_opts->has_devname ? netmap_opts->devname : "/dev/netmap");
> -    /* Set default name for the port if not supplied. */
> -    pstrcpy(me.ifname, sizeof(me.ifname), netmap_opts->ifname);
> -    netmap_open(&me, &err);
> +    nmd = netmap_open(netmap_opts, &err);
>      if (err) {
>          error_propagate(errp, err);
>          return -1;
> @@ -454,8 +418,11 @@ int net_init_netmap(const NetClientOptions *opts,
>      /* Create the object. */
>      nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
>      s = DO_UPCAST(NetmapState, nc, nc);
> -    s->me = me;
> +    s->nmd = nmd;
> +    s->tx = NETMAP_TXRING(nmd->nifp, 0);
> +    s->rx = NETMAP_RXRING(nmd->nifp, 0);
>      s->vnet_hdr_len = 0;
> +    pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
>      netmap_read_poll(s, true); /* Initially only poll for reads. */
>  
>      return 0;