Re: [Xen-devel] [PATCH v2 5/9] xen/9pfs: connect to the frontend

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 14 Mar 2017, Juergen Gross wrote:
> On 14/03/17 00:55, Stefano Stabellini wrote:
> > Write the limits of the backend to xenstore. Connect to the frontend.
> > Upon connection, allocate the rings according to the protocol
> > specification.
> > 
> > Initialize a QEMUBH to schedule work upon receiving an event channel
> > notification from the frontend.
> > 
> > Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
> > CC: anthony.perard@xxxxxxxxxx
> > CC: jgross@xxxxxxxx
> > CC: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> > CC: Greg Kurz <groug@xxxxxxxx>
> > ---
> >  hw/9pfs/xen-9p-backend.c | 159 
> > ++++++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 158 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/9pfs/xen-9p-backend.c b/hw/9pfs/xen-9p-backend.c
> > index 35032d3..0e4a133 100644
> > --- a/hw/9pfs/xen-9p-backend.c
> > +++ b/hw/9pfs/xen-9p-backend.c
> > @@ -17,8 +17,35 @@
> >  #include "qemu/config-file.h"
> >  #include "fsdev/qemu-fsdev.h"
> >  
> > +#define VERSIONS "1"
> > +#define MAX_RINGS 8
> > +#define MAX_RING_ORDER 8
> > +
> > +struct Xen9pfsRing {
> > +    struct Xen9pfsDev *priv;
> > +
> > +    int ref;
> > +    xenevtchn_handle   *evtchndev;
> > +    int evtchn;
> > +    int local_port;
> > +    struct xen_9pfs_data_intf *intf;
> > +    unsigned char *data;
> > +    struct xen_9pfs_data ring;
> > +
> > +    QEMUBH *bh;
> > +
> > +    /* local copies, so that we can read/write PDU data directly from
> > +     * the ring */
> > +    RING_IDX out_cons, out_size, in_cons;
> > +    bool inprogress;
> > +};
> > +
> >  typedef struct Xen9pfsDev {
> >      struct XenDevice xendev;  /* must be first */
> > +    V9fsState state;
> > +
> > +    int num_rings;
> > +    struct Xen9pfsRing *rings;
> >  } Xen9pfsDev;
> >  
> >  static ssize_t xen_9pfs_pdu_vmarshal(V9fsPDU *pdu,
> > @@ -67,22 +94,152 @@ static int xen_9pfs_init(struct XenDevice *xendev)
> >      return 0;
> >  }
> >  
> > +static void xen_9pfs_bh(void *opaque)
> > +{
> > +}
> > +
> > +static void xen_9pfs_evtchn_event(void *opaque)
> > +{
> > +}
> > +
> >  static int xen_9pfs_free(struct XenDevice *xendev)
> >  {
> > -    return -1;
> > +    int i;
> > +    struct Xen9pfsDev *xen_9pdev = container_of(xendev, struct Xen9pfsDev, 
> > xendev);
> > +
> > +    for (i = 0; i < xen_9pdev->num_rings; i++) {
> > +        if (xen_9pdev->rings[i].data != NULL) {
> > +            xengnttab_unmap(xen_9pdev->xendev.gnttabdev,
> > +                    xen_9pdev->rings[i].data,
> > +                    (1 << XEN_9PFS_RING_ORDER));
> > +        }
> > +        if (xen_9pdev->rings[i].intf != NULL) {
> > +            xengnttab_unmap(xen_9pdev->xendev.gnttabdev,
> > +                    xen_9pdev->rings[i].intf,
> > +                    1);
> > +        }
> > +        if (xen_9pdev->rings[i].evtchndev > 0) {
> > +            
> > qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
> > +                    NULL, NULL, NULL);
> > +            xenevtchn_unbind(xen_9pdev->rings[i].evtchndev, 
> > xen_9pdev->rings[i].local_port);
> > +        }
> > +        if (xen_9pdev->rings[i].bh != NULL) {
> > +            qemu_bh_delete(xen_9pdev->rings[i].bh);
> > +        }
> > +    }
> > +    g_free(xen_9pdev->rings);
> > +    return 0;
> >  }
> >  
> >  static int xen_9pfs_connect(struct XenDevice *xendev)
> >  {
> > +    int i;
> > +    struct Xen9pfsDev *xen_9pdev = container_of(xendev, struct Xen9pfsDev, 
> > xendev);
> > +    V9fsState *s = &xen_9pdev->state;
> > +    QemuOpts *fsdev;
> > +    char *security_model, *path;
> > +
> > +    if (xenstore_read_fe_int(&xen_9pdev->xendev, "num-rings",
> > +                             &xen_9pdev->num_rings) == -1 ||
> > +        xen_9pdev->num_rings > MAX_RINGS) {
> 
> What if num_rings is < 1?

Good point, I'll add a check for that


> > +        return -1;
> > +    }
> > +
> > +    xen_9pdev->rings = g_malloc0(xen_9pdev->num_rings * sizeof(struct 
> > Xen9pfsRing));
> > +    for (i = 0; i < xen_9pdev->num_rings; i++) {
> > +        char str[16];
> > +
> > +        xen_9pdev->rings[i].priv = xen_9pdev;
> > +        xen_9pdev->rings[i].evtchn = -1;
> > +        xen_9pdev->rings[i].local_port = -1;
> > +
> > +        sprintf(str, "ring-ref%u", i);
> 
> use g_strdup_printf()?

OK


> > +        if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
> > +                                 &xen_9pdev->rings[i].ref) == -1) {
> > +            goto out;
> > +        }
> > +        sprintf(str, "event-channel-%u", i);
> 
> use g_strdup_printf()?

Sure

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