core: stop probing known-unusable ports early

Some ports we know we shouldn't use when we get certain responses
from them.  Reading from these ports triggers kernel bugs (at least
on 2.6.31 and 2.6.32) relating to flow control in some drivers
(*cough* hso *cough*), so lets try not to aggravate the kernel too
much.  This happens on Icera-based Option devices like the GI0322
(AT&T Quicksilver) for example.

(note: AFAICT this doesn't have any relation to the recent XON/XOFF
patch, since I get this problem without the XON/XOFF patch on both
2.6.31 and 2.6.32 as well)

---

BUG: sleeping function called from invalid context at kernel/mutex.c:94
in_atomic(): 1, irqs_disabled(): 1, pid: 9295, name: modem-manager
Pid: 9295, comm: modem-manager Not tainted 2.6.32.9-67.fc12.x86_64 #1
Call Trace:
 <IRQ>  [<ffffffff81045d41>] __might_sleep+0xed/0xef
 [<ffffffff81454dd0>] mutex_lock+0x24/0x50
 [<ffffffff8104811e>] ? enqueue_task_fair+0x2a/0x6d
 [<ffffffff812af79f>] tty_throttle+0x1b/0x49
 [<ffffffff812af0d9>] n_tty_receive_buf+0xdbb/0xe12
 [<ffffffff810459fd>] ? task_rq_unlock+0x11/0x13
 [<ffffffff81050c5c>] ? try_to_wake_up+0x2f3/0x305
 [<ffffffff8110de0c>] ? __kmalloc+0x37/0x15e
 [<ffffffff8110de42>] ? __kmalloc+0x6d/0x15e
 [<ffffffff812b12c9>] flush_to_ldisc+0xf8/0x18d
 [<ffffffff812b13ae>] tty_flip_buffer_push+0x50/0x61
 [<ffffffffa040ccd5>] put_rxbuf_data+0xea/0x124 [hso]
 [<ffffffffa040cd97>] put_rxbuf_data_and_resubmit_bulk_urb+0x21/0x6b [hso]
 [<ffffffffa040d0b1>] hso_std_serial_read_bulk_callback+0x14d/0x15f [hso]
 [<ffffffff8132edf7>] ? dma_unmap_single_attrs.clone.0+0x38/0x3a
 [<ffffffff8132ef74>] usb_hcd_giveback_urb+0x91/0xc5
 [<ffffffff813417c8>] ehci_urb_done+0x7b/0x90
 [<ffffffff81050c5c>] ? try_to_wake_up+0x2f3/0x305
 [<ffffffff81341b45>] qh_completions+0x368/0x4b9
 [<ffffffff8103e7a0>] ? __wake_up_common+0x4e/0x84
 [<ffffffff81343f70>] ehci_work+0x95/0x732
 [<ffffffff81045b53>] ? __wake_up+0x44/0x4d
 [<ffffffff81070490>] ? insert_work+0x8e/0x9b
 [<ffffffff81345f01>] ehci_irq+0x2be/0x420
 [<ffffffff8107071a>] ? __queue_work+0x3a/0x41
 [<ffffffff81049e43>] ? resched_cpu+0x6e/0x77
 [<ffffffff8107075d>] ? delayed_work_timer_fn+0x3c/0x3e
 [<ffffffff810b0e44>] ? __rcu_process_callbacks+0x7d/0x28a
 [<ffffffff8132e846>] usb_hcd_irq+0x3f/0x7b
 [<ffffffff810acd61>] handle_IRQ_event+0x60/0x121
 [<ffffffff810aeb8e>] handle_fasteoi_irq+0x8b/0xc7
 [<ffffffff81014625>] handle_irq+0x8b/0x96
 [<ffffffff81459c14>] do_IRQ+0x5c/0xbc
 [<ffffffff81012693>] ret_from_intr+0x0/0x11

1 files changed, 22 insertions, 7 deletions

diff --git a/src/mm-serial-port.c b/src/mm-serial-port.c
index 1d98a537..2134751f 100644
--- a/src/mm-serial-port.c
+++ b/src/mm-serial-port.c
@@ -730,9 +730,13 @@ data_available (GIOChannel *source,
 
         status = g_io_channel_read_chars (source, buf, SERIAL_BUF_SIZE, &bytes_read, &err);
         if (status == G_IO_STATUS_ERROR) {
-            g_warning ("%s", err->message);
-            g_error_free (err);
-            err = NULL;
+            if (err && err->message)
+                g_warning ("%s", err->message);
+            g_clear_error (&err);
+
+            /* Serial port is closed; we're done */
+            if (priv->watch_id == 0)
+                break;
         }
 
         /* If no bytes read, just let g_io_channel wait for more data */
@@ -745,10 +749,10 @@ data_available (GIOChannel *source,
         }
 
         /* Make sure the string doesn't grow too long */
-		if (priv->response->len > SERIAL_BUF_SIZE) {
-			g_warning ("%s (%s): response buffer filled before repsonse received",
-			           G_STRFUNC, mm_port_get_device (MM_PORT (self)));
-			g_string_erase (priv->response, 0, (SERIAL_BUF_SIZE / 2));
+        if (priv->response->len > SERIAL_BUF_SIZE) {
+            /* Notify listeners and then trim the buffer */
+            g_signal_emit_by_name (self, "buffer-full", priv->response);
+            g_string_erase (priv->response, 0, (SERIAL_BUF_SIZE / 2));
         }
 
         if (parse_response (self, priv->response, &err))
@@ -888,6 +892,7 @@ mm_serial_port_close (MMSerialPort *self)
 
         if (priv->channel) {
             g_source_remove (priv->watch_id);
+            priv->watch_id = 0;
             g_io_channel_shutdown (priv->channel, TRUE, NULL);
             g_io_channel_unref (priv->channel);
             priv->channel = NULL;
@@ -1293,4 +1298,14 @@ mm_serial_port_class_init (MMSerialPortClass *klass)
                               "Send delay",
                               0, G_MAXUINT64, 0,
                               G_PARAM_READWRITE));
+
+    /* Signals */
+    g_signal_new ("buffer-full",
+                  G_OBJECT_CLASS_TYPE (object_class),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (MMSerialPortClass, buffer_full),
+                  NULL, NULL,
+                  g_cclosure_marshal_VOID__POINTER,
+                  G_TYPE_NONE, 1, G_TYPE_POINTER);
 }
+