Changeset 7d1dd2b in mainline

Timestamp:

2018-01-16T13:36:30Z (7 years ago)

Author:

Ondřej Hlavatý <aearsis@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

47e9494

Parents:

c952abc4

git-author:

Ondřej Hlavatý <aearsis@…> (2018-01-16 13:36:28)

git-committer:

Ondřej Hlavatý <aearsis@…> (2018-01-16 13:36:30)

Message:

usbhub: port simply cannot inform HC when finalizing

There are three options regarding port finalization with device
connected and enabled:

1) Wait until HC disposes the device. Sorry, no, IPC deadlock, because

if the device is a hub, it will need to use the same connection that
is finalizing the port.

2) Create a fibril to announce this to HC. Yeah, no more deadlock, but

race condition. Host controller will want to clean up after the hub,
and will remove devices connected to it as soon as the unbinding
finishes.

3) If he is doing so… lets leave it up to him? That makes HC spit

a warning, but it's the only correct option then.

File:

• uspace/drv/bus/usb/usbhub/port.c (modified) (1 diff)

uspace/drv/bus/usb/usbhub/port.c

@@ -153 +153 @@
 {
         assert(port);
+
         fibril_mutex_lock(&port->guard);
-        port_make_disabled(port);
+        switch (port->state) {
+        case PORT_ENABLED:
+                /*
+                 * We shall inform the HC that the device is gone.
+                 * However, we can't wait for it, because if the device is hub,
+                 * it would have to use the same IPC handling fibril as we do.
+                 * But we cannot even defer it to another fibril, because then
+                 * the HC would assume our driver didn't cleanup properly, and
+                 * will remove those devices by himself.
+                 *
+                 * So the solutions seems to behave like a bad driver and leave
+                 * the work for HC.
+                 */
+                port_change_state(port, PORT_DISABLED);
+                break;
+
+        case PORT_CONNECTED:
+        case PORT_IN_RESET:
+                port_change_state(port, PORT_ERROR);
+                /* fallthrough */
+        case PORT_ERROR:
+                port_wait_state(port, PORT_DISABLED);
+                /* fallthrough */
+        case PORT_DISABLED:
+                break;
+        }
         port_log(debug, port, "Finalized.");
         fibril_mutex_unlock(&port->guard);