On Wed, Nov 1, 2023 at 5:34 AM Juergen Gross <jgr...@suse.com> wrote:
>
> Add the code for connecting to frontends to xenlogd.
>
> Signed-off-by: Juergen Gross <jgr...@suse.com>
> diff --git a/tools/xenlogd/xenlogd.c b/tools/xenlogd/xenlogd.c
> index 792d1026a3..da0a09a122 100644
> --- a/tools/xenlogd/xenlogd.c
> +++ b/tools/xenlogd/xenlogd.c
> +static void connect_device(device *device)
> +{
> + unsigned int val;
> + xenevtchn_port_or_error_t evtchn;
1.> +
> + val = read_frontend_node_uint(device, "version", 0);
> + if ( val != 1 )
> + return connect_err(device, "frontend specifies illegal version");
> + val = read_frontend_node_uint(device, "num-rings", 0);
> + if ( val != 1 )
> + return connect_err(device, "frontend specifies illegal ring number");
Linux uses 2 rings (XEN_9PFS_NUM_RINGS), and it doesn't connect when
max-rings is less than that.
max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
if (max_rings < XEN_9PFS_NUM_RINGS)
return -EINVAL;
new_device() writes max-rings as 1. So this works for mini-os, but
not Linux. I'm not requesting you to change it - just noting it.
> +
> + val = read_frontend_node_uint(device, "event-channel-0", 0);
> + if ( val == 0 )
> + return connect_err(device, "frontend specifies illegal evtchn");
> + evtchn = xenevtchn_bind_interdomain(xe, device->domid, val);
> + if ( evtchn < 0 )
> + return connect_err(device, "could not bind to event channel");
> + device->evtchn = evtchn;
> +
> + val = read_frontend_node_uint(device, "ring-ref0", 0);
> + if ( val == 0 )
> + return connect_err(device, "frontend specifies illegal grant for
> ring");
> + device->intf = xengnttab_map_grant_ref(xg, device->domid, val,
> + PROT_READ | PROT_WRITE);
> + if ( !device->intf )
> + return connect_err(device, "could not map interface page");
> + device->ring_order = device->intf->ring_order;
> + if ( device->ring_order > 9 || device->ring_order < 1 )
> + return connect_err(device, "frontend specifies illegal ring order");
> + device->ring_size = XEN_FLEX_RING_SIZE(device->ring_order);
> + device->data.in = xengnttab_map_domain_grant_refs(xg,
> + 1 <<
> device->ring_order,
> + device->domid,
> + device->intf->ref,
> + PROT_READ |
> PROT_WRITE);
> + if ( !device->data.in )
> + return connect_err(device, "could not map ring pages");
> + device->data.out = device->data.in + device->ring_size;
> +
> + if ( pthread_create(&device->thread, NULL, io_thread, device) )
> + return connect_err(device, "could not start I/O thread");
> + device->thread_active = true;
> +
> + write_backend_state(device, XenbusStateConnected);
> +}
> +
> @@ -122,6 +669,11 @@ int main(int argc, char *argv[])
> int syslog_mask = LOG_MASK(LOG_WARNING) | LOG_MASK(LOG_ERR) |
> LOG_MASK(LOG_CRIT) | LOG_MASK(LOG_ALERT) |
> LOG_MASK(LOG_EMERG);
> + char **watch;
> + struct pollfd p[2] = {
> + { .events = POLLIN, .revents = POLLIN },
Are you intentionally setting revents to enter the loop initially?
Shouldn't the watch registration trigger it to fire anyway?
> + { .events = POLLIN }
> + };
>
> umask(027);
> if ( getenv("XENLOGD_VERBOSE") )
> @@ -134,9 +686,26 @@ int main(int argc, char *argv[])
>
> xen_connect();
>
> + if ( !xs_watch(xs, "backend/xen_9pfs", "main") )
> + do_err("xs_watch() in main thread failed");
> + p[0].fd = xs_fileno(xs);
> + p[1].fd = xenevtchn_fd(xe);
> +
> + scan_backend();
> +
> while ( !stop_me )
> {
> - sleep(60);
> + while ( (p[0].revents & POLLIN) &&
> + (watch = xs_check_watch(xs)) != NULL )
> + {
> + handle_watch(watch[XS_WATCH_PATH], watch[XS_WATCH_TOKEN]);
> + free(watch);
> + }
> +
> + if ( p[1].revents & POLLIN )
> + handle_event();
> +
> + poll(p, 2, 10000);
Can you just use an infinite timeout and rely on the signal
interrupting the system call?
Regards,
Jason
