HID: remove setup mutex, fix possible deadlock
Jiri Slaby [Sun, 23 Nov 2008 11:03:20 +0000 (12:03 +0100)]
It causes recursive locking warning and is unneeded after
introduction of STARTED flag.

* Resume vs. stop is effectively solved by DISCONNECT flag.
* No problem in suspend vs. start -- urb is submitted even after open
  which is possible after connect which is called after start.
* Resume vs. start solved by STARTED flag.
* Suspend vs. stop -- no problem in killing urb and timer twice.

Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/usbhid/hid-core.c
drivers/hid/usbhid/usbhid.h

index d746bf8..606369e 100644 (file)
@@ -796,7 +796,6 @@ static int usbhid_start(struct hid_device *hid)
        if (insize > HID_MAX_BUFFER_SIZE)
                insize = HID_MAX_BUFFER_SIZE;
 
-       mutex_lock(&usbhid->setup);
        if (hid_alloc_buffers(dev, hid)) {
                ret = -ENOMEM;
                goto fail;
@@ -876,7 +875,6 @@ static int usbhid_start(struct hid_device *hid)
        hid_dump_device(hid);
 
        set_bit(HID_STARTED, &usbhid->iofl);
-       mutex_unlock(&usbhid->setup);
 
        return 0;
 
@@ -888,7 +886,6 @@ fail:
        usbhid->urbout = NULL;
        usbhid->urbctrl = NULL;
        hid_free_buffers(dev, hid);
-       mutex_unlock(&usbhid->setup);
        return ret;
 }
 
@@ -899,7 +896,6 @@ static void usbhid_stop(struct hid_device *hid)
        if (WARN_ON(!usbhid))
                return;
 
-       mutex_lock(&usbhid->setup);
        clear_bit(HID_STARTED, &usbhid->iofl);
        spin_lock_irq(&usbhid->inlock); /* Sync with error handler */
        set_bit(HID_DISCONNECTED, &usbhid->iofl);
@@ -928,7 +924,6 @@ static void usbhid_stop(struct hid_device *hid)
        usbhid->urbout = NULL;
 
        hid_free_buffers(hid_to_usb_dev(hid), hid);
-       mutex_unlock(&usbhid->setup);
 }
 
 static struct hid_ll_driver usb_hid_driver = {
@@ -1016,7 +1011,6 @@ static int hid_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
        hid->driver_data = usbhid;
        usbhid->hid = hid;
-       mutex_init(&usbhid->setup); /* needed on suspend/resume */
 
        ret = hid_add_device(hid);
        if (ret) {
@@ -1051,18 +1045,14 @@ static int hid_suspend(struct usb_interface *intf, pm_message_t message)
        struct hid_device *hid = usb_get_intfdata (intf);
        struct usbhid_device *usbhid = hid->driver_data;
 
-       mutex_lock(&usbhid->setup);
-       if (!test_bit(HID_STARTED, &usbhid->iofl)) {
-               mutex_unlock(&usbhid->setup);
+       if (!test_bit(HID_STARTED, &usbhid->iofl))
                return 0;
-       }
 
        spin_lock_irq(&usbhid->inlock); /* Sync with error handler */
        set_bit(HID_SUSPENDED, &usbhid->iofl);
        spin_unlock_irq(&usbhid->inlock);
        del_timer_sync(&usbhid->io_retry);
        usb_kill_urb(usbhid->urbin);
-       mutex_unlock(&usbhid->setup);
        dev_dbg(&intf->dev, "suspend\n");
        return 0;
 }
@@ -1073,16 +1063,12 @@ static int hid_resume(struct usb_interface *intf)
        struct usbhid_device *usbhid = hid->driver_data;
        int status;
 
-       mutex_lock(&usbhid->setup);
-       if (!test_bit(HID_STARTED, &usbhid->iofl)) {
-               mutex_unlock(&usbhid->setup);
+       if (!test_bit(HID_STARTED, &usbhid->iofl))
                return 0;
-       }
 
        clear_bit(HID_SUSPENDED, &usbhid->iofl);
        usbhid->retry_delay = 0;
        status = hid_start_in(hid);
-       mutex_unlock(&usbhid->setup);
        dev_dbg(&intf->dev, "resume status %d\n", status);
        return status;
 }
index 55973ff..332abcd 100644 (file)
@@ -74,7 +74,6 @@ struct usbhid_device {
        dma_addr_t outbuf_dma;                                          /* Output buffer dma */
        spinlock_t outlock;                                             /* Output fifo spinlock */
 
-       struct mutex setup;
        unsigned long iofl;                                             /* I/O flags (CTRL_RUNNING, OUT_RUNNING) */
        struct timer_list io_retry;                                     /* Retry timer */
        unsigned long stop_retry;                                       /* Time to give up, in jiffies */