usb-host: limit open retries

Limit the number of times qemu tries to open host devices to three.
Reset error counter when the device goes away, after un-plugging and
re-plugging the device qemu will try again three times.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/usb-linux.c b/usb-linux.c
index 344af22..36d25d7 100644 (file)
--- a/usb-linux.c
+++ b/usb-linux.c
@@ -132,6 +132,7 @@ typedef struct USBHostDevice {
     int addr;
     char port[MAX_PORTLEN];
     struct USBAutoFilter match;
+    int seen, errcount;
 
     QTAILQ_ENTRY(USBHostDevice) next;
 } USBHostDevice;
@@ -1769,6 +1770,10 @@ static int usb_host_auto_scan(void *opaque, int bus_num, int addr, char *port,
             continue;
         }
         /* We got a match */
+        s->seen++;
+        if (s->errcount >= 3) {
+            return 0;
+        }
 
         /* Already attached ? */
         if (s->fd != -1) {
@@ -1776,7 +1781,9 @@ static int usb_host_auto_scan(void *opaque, int bus_num, int addr, char *port,
         }
         DPRINTF("husb: auto open: bus_num %d addr %d\n", bus_num, addr);
 
-        usb_host_open(s, bus_num, addr, port, product_name, speed);
+        if (usb_host_open(s, bus_num, addr, port, product_name, speed) < 0) {
+            s->errcount++;
+        }
         break;
     }
 
@@ -1794,6 +1801,10 @@ static void usb_host_auto_check(void *unused)
         if (s->fd == -1) {
             unconnected++;
         }
+        if (s->seen == 0) {
+            s->errcount = 0;
+        }
+        s->seen = 0;
     }
 
     if (unconnected == 0) {