diff options
author | Du Xing <duxing2007@gmail.com> | 2013-03-20 12:47:46 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-25 20:32:20 (GMT) |
commit | c79041a44045a40329d9ada3f8679c4b30c5b76b (patch) | |
tree | ade4c7d97b3569aa04ec5f48eaa4a22a99583291 /drivers/usb | |
parent | 3edce1cf813aa6a087df7730cec0e67d57288300 (diff) | |
download | linux-c79041a44045a40329d9ada3f8679c4b30c5b76b.tar.xz |
USB: usb-skeleton.c: fix blocked forever in skel_read
In skel_read,the reader blocked in wait_for_completion before submit
bulk in urb.
Using processed_urb is for retaining the completion in the case that
previous interruptible wait in skel_read was interrupted and complete
before next skel_read. Replacing completion with waitqueue can avoid
working around the counting nature of completions
and fix the bug.
Signed-off-by: Du Xing duxing2007@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r-- | drivers/usb/usb-skeleton.c | 32 |
1 files changed, 8 insertions, 24 deletions
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index ce310170..7ed3b03 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -61,11 +61,10 @@ struct usb_skel { __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ int errors; /* the last request tanked */ bool ongoing_read; /* a read is going on */ - bool processed_urb; /* indicates we haven't processed the urb */ spinlock_t err_lock; /* lock for errors */ struct kref kref; struct mutex io_mutex; /* synchronize I/O with disconnect */ - struct completion bulk_in_completion; /* to wait for an ongoing read */ + wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */ }; #define to_skel_dev(d) container_of(d, struct usb_skel, kref) @@ -185,7 +184,7 @@ static void skel_read_bulk_callback(struct urb *urb) dev->ongoing_read = 0; spin_unlock(&dev->err_lock); - complete(&dev->bulk_in_completion); + wake_up_interruptible(&dev->bulk_in_wait); } static int skel_do_read_io(struct usb_skel *dev, size_t count) @@ -206,13 +205,16 @@ static int skel_do_read_io(struct usb_skel *dev, size_t count) dev->ongoing_read = 1; spin_unlock_irq(&dev->err_lock); + /* submit bulk in urb, which means no data to deliver */ + dev->bulk_in_filled = 0; + dev->bulk_in_copied = 0; + /* do it */ rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL); if (rv < 0) { dev_err(&dev->interface->dev, "%s - failed submitting read urb, error %d\n", __func__, rv); - dev->bulk_in_filled = 0; rv = (rv == -ENOMEM) ? rv : -EIO; spin_lock_irq(&dev->err_lock); dev->ongoing_read = 0; @@ -261,25 +263,9 @@ retry: * IO may take forever * hence wait in an interruptible state */ - rv = wait_for_completion_interruptible(&dev->bulk_in_completion); + rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read)); if (rv < 0) goto exit; - /* - * by waiting we also semiprocessed the urb - * we must finish now - */ - dev->bulk_in_copied = 0; - dev->processed_urb = 1; - } - - if (!dev->processed_urb) { - /* - * the URB hasn't been processed - * do it now - */ - wait_for_completion(&dev->bulk_in_completion); - dev->bulk_in_copied = 0; - dev->processed_urb = 1; } /* errors must be reported */ @@ -289,8 +275,6 @@ retry: dev->errors = 0; /* to preserve notifications about reset */ rv = (rv == -EPIPE) ? rv : -EIO; - /* no data to deliver */ - dev->bulk_in_filled = 0; /* report it */ goto exit; } @@ -526,7 +510,7 @@ static int skel_probe(struct usb_interface *interface, mutex_init(&dev->io_mutex); spin_lock_init(&dev->err_lock); init_usb_anchor(&dev->submitted); - init_completion(&dev->bulk_in_completion); + init_waitqueue_head(&dev->bulk_in_wait); dev->udev = usb_get_dev(interface_to_usbdev(interface)); dev->interface = interface; |