usb: cdc-wdm: Fix race between autosuspend and reading from the device

While an available response is read the device must not
be autosuspended. This requires a flag dedicated to that
purpose.

Signed-off-by: Oliver Neukum <neukum@b1-systems.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index cf1c5fb..940b17a 100644 (file)
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -52,6 +52,7 @@ MODULE_DEVICE_TABLE (usb, wdm_ids);
 #define WDM_READ               4
 #define WDM_INT_STALL          5
 #define WDM_POLL_RUNNING       6
+#define WDM_RESPONDING         7
 
 
 #define WDM_MAX                        16
@@ -115,21 +116,22 @@ static void wdm_in_callback(struct urb *urb)
        int status = urb->status;
 
        spin_lock(&desc->iuspin);
+       clear_bit(WDM_RESPONDING, &desc->flags);
 
        if (status) {
                switch (status) {
                case -ENOENT:
                        dev_dbg(&desc->intf->dev,
                                "nonzero urb status received: -ENOENT");
-                       break;
+                       goto skip_error;
                case -ECONNRESET:
                        dev_dbg(&desc->intf->dev,
                                "nonzero urb status received: -ECONNRESET");
-                       break;
+                       goto skip_error;
                case -ESHUTDOWN:
                        dev_dbg(&desc->intf->dev,
                                "nonzero urb status received: -ESHUTDOWN");
-                       break;
+                       goto skip_error;
                case -EPIPE:
                        dev_err(&desc->intf->dev,
                                "nonzero urb status received: -EPIPE\n");
@@ -145,6 +147,7 @@ static void wdm_in_callback(struct urb *urb)
        desc->reslength = urb->actual_length;
        memmove(desc->ubuf + desc->length, desc->inbuf, desc->reslength);
        desc->length += desc->reslength;
+skip_error:
        wake_up(&desc->wait);
 
        set_bit(WDM_READ, &desc->flags);
@@ -227,6 +230,7 @@ static void wdm_int_callback(struct urb *urb)
        desc->response->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
        spin_lock(&desc->iuspin);
        clear_bit(WDM_READ, &desc->flags);
+       set_bit(WDM_RESPONDING, &desc->flags);
        if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
                rv = usb_submit_urb(desc->response, GFP_ATOMIC);
                dev_dbg(&desc->intf->dev, "%s: usb_submit_urb %d",
@@ -234,6 +238,7 @@ static void wdm_int_callback(struct urb *urb)
        }
        spin_unlock(&desc->iuspin);
        if (rv < 0) {
+               clear_bit(WDM_RESPONDING, &desc->flags);
                if (rv == -EPERM)
                        return;
                if (rv == -ENOMEM) {
@@ -795,7 +800,8 @@ static int wdm_suspend(struct usb_interface *intf, pm_message_t message)
        mutex_lock(&desc->lock);
 #ifdef CONFIG_PM
        if ((message.event & PM_EVENT_AUTO) &&
-                       test_bit(WDM_IN_USE, &desc->flags)) {
+                       (test_bit(WDM_IN_USE, &desc->flags)
+                       || test_bit(WDM_RESPONDING, &desc->flags))) {
                rv = -EBUSY;
        } else {
 #endif