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>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index cf1c5fb918dc..940b17af162c 100644
--- 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