USB: ldusb bugfix

This patch fixes a problem reported with consecutive reads in the ldusb
driver.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/misc/ldusb.c b/drivers/usb/misc/ldusb.c
index 11555bde655bf16c6fc2b049aea6910b1a808fba..7bad494047621a38f61bd8cf90057f2d40870ea7 100644 (file)
--- a/drivers/usb/misc/ldusb.c
+++ b/drivers/usb/misc/ldusb.c
@@ -165,6 +165,8 @@ struct ld_usb {
        size_t                  interrupt_in_endpoint_size;
        int                     interrupt_in_running;
        int                     interrupt_in_done;
+       int                     buffer_overflow;
+       spinlock_t              rbsl;
 
        char*                   interrupt_out_buffer;
        struct usb_endpoint_descriptor* interrupt_out_endpoint;
@@ -230,10 +232,12 @@ static void ld_usb_interrupt_in_callback(struct urb *urb)
                } else {
                        dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
                                 __FUNCTION__, urb->status);
+                       spin_lock(&dev->rbsl);
                        goto resubmit; /* maybe we can recover */
                }
        }
 
+       spin_lock(&dev->rbsl);
        if (urb->actual_length > 0) {
                next_ring_head = (dev->ring_head+1) % ring_buffer_size;
                if (next_ring_head != dev->ring_tail) {
@@ -244,21 +248,25 @@ static void ld_usb_interrupt_in_callback(struct urb *urb)
                        dev->ring_head = next_ring_head;
                        dbg_info(&dev->intf->dev, "%s: received %d bytes\n",
                                 __FUNCTION__, urb->actual_length);
-               } else
+               } else {
                        dev_warn(&dev->intf->dev,
                                 "Ring buffer overflow, %d bytes dropped\n",
                                 urb->actual_length);
+                       dev->buffer_overflow = 1;
+               }
        }
 
 resubmit:
        /* resubmit if we're still running */
-       if (dev->interrupt_in_running && dev->intf) {
+       if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) {
                retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
-               if (retval)
+               if (retval) {
                        dev_err(&dev->intf->dev,
                                "usb_submit_urb failed (%d)\n", retval);
+                       dev->buffer_overflow = 1;
+               }
        }
-
+       spin_unlock(&dev->rbsl);
 exit:
        dev->interrupt_in_done = 1;
        wake_up_interruptible(&dev->read_wait);
@@ -330,6 +338,7 @@ static int ld_usb_open(struct inode *inode, struct file *file)
        /* initialize in direction */
        dev->ring_head = 0;
        dev->ring_tail = 0;
+       dev->buffer_overflow = 0;
        usb_fill_int_urb(dev->interrupt_in_urb,
                         interface_to_usbdev(interface),
                         usb_rcvintpipe(interface_to_usbdev(interface),
@@ -439,6 +448,7 @@ static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
        size_t *actual_buffer;
        size_t bytes_to_read;
        int retval = 0;
+       int rv;
 
        dev = file->private_data;
 
@@ -460,7 +470,10 @@ static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
        }
 
        /* wait for data */
+       spin_lock_irq(&dev->rbsl);
        if (dev->ring_head == dev->ring_tail) {
+               dev->interrupt_in_done = 0;
+               spin_unlock_irq(&dev->rbsl);
                if (file->f_flags & O_NONBLOCK) {
                        retval = -EAGAIN;
                        goto unlock_exit;
@@ -468,6 +481,8 @@ static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
                retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
                if (retval < 0)
                        goto unlock_exit;
+       } else {
+               spin_unlock_irq(&dev->rbsl);
        }
 
        /* actual_buffer contains actual_length + interrupt_in_buffer */
@@ -486,6 +501,17 @@ static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
 
        retval = bytes_to_read;
 
+       spin_lock_irq(&dev->rbsl);
+       if (dev->buffer_overflow) {
+               dev->buffer_overflow = 0;
+               spin_unlock_irq(&dev->rbsl);
+               rv = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+               if (rv < 0)
+                       dev->buffer_overflow = 1;
+       } else {
+               spin_unlock_irq(&dev->rbsl);
+       }
+
 unlock_exit:
        /* unlock the device */
        up(&dev->sem);
@@ -635,6 +661,7 @@ static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *
                goto exit;
        }
        init_MUTEX(&dev->sem);
+       spin_lock_init(&dev->rbsl);
        dev->intf = intf;
        init_waitqueue_head(&dev->read_wait);
        init_waitqueue_head(&dev->write_wait);