cdc-wdm: Don't clear WDM_READ unless entire read buffer is emptied

[pandora-kernel.git] / drivers / usb / class / cdc-wdm.c

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index d2cda26..9eb71d8 100644 (file)
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -57,6 +57,8 @@ MODULE_DEVICE_TABLE (usb, wdm_ids);
 
 #define WDM_MAX                        16
 
+/* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */
+#define WDM_DEFAULT_BUFSIZE    256
 
 static DEFINE_MUTEX(wdm_mutex);
 
@@ -395,7 +397,7 @@ outnl:
 static ssize_t wdm_read
 (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 {
-       int rv, cntr = 0;
+       int rv, cntr;
        int i = 0;
        struct wdm_device *desc = file->private_data;
 
@@ -404,7 +406,8 @@ static ssize_t wdm_read
        if (rv < 0)
                return -ERESTARTSYS;
 
-       if (desc->length == 0) {
+       cntr = ACCESS_ONCE(desc->length);
+       if (cntr == 0) {
                desc->read = 0;
 retry:
                if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
@@ -454,26 +457,30 @@ retry:
                        spin_unlock_irq(&desc->iuspin);
                        goto retry;
                }
-               clear_bit(WDM_READ, &desc->flags);
+               cntr = desc->length;
                spin_unlock_irq(&desc->iuspin);
        }
 
-       cntr = count > desc->length ? desc->length : count;
+       if (cntr > count)
+               cntr = count;
        rv = copy_to_user(buffer, desc->ubuf, cntr);
        if (rv > 0) {
                rv = -EFAULT;
                goto err;
        }
 
+       spin_lock_irq(&desc->iuspin);
+
        for (i = 0; i < desc->length - cntr; i++)
                desc->ubuf[i] = desc->ubuf[i + cntr];
 
-       spin_lock_irq(&desc->iuspin);
        desc->length -= cntr;
-       spin_unlock_irq(&desc->iuspin);
        /* in case we had outstanding data */
        if (!desc->length)
                clear_bit(WDM_READ, &desc->flags);
+
+       spin_unlock_irq(&desc->iuspin);
+
        rv = cntr;
 
 err:
@@ -636,7 +643,7 @@ static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
        struct usb_cdc_dmm_desc *dmhd;
        u8 *buffer = intf->altsetting->extra;
        int buflen = intf->altsetting->extralen;
-       u16 maxcom = 0;
+       u16 maxcom = WDM_DEFAULT_BUFSIZE;
 
        if (!buffer)
                goto out;
@@ -723,7 +730,7 @@ next_desc:
                goto err;
 
        desc->inbuf = usb_alloc_coherent(interface_to_usbdev(intf),
-                                        desc->bMaxPacketSize0,
+                                        desc->wMaxCommand,
                                         GFP_KERNEL,
                                         &desc->response->transfer_dma);
        if (!desc->inbuf)