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
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -52,6 +52,7 @@
#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 @@
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 @@
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 @@
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 @@
}
spin_unlock(&desc->iuspin);
if (rv < 0) {
+ clear_bit(WDM_RESPONDING, &desc->flags);
if (rv == -EPERM)
return;
if (rv == -ENOMEM) {
@@ -795,7 +800,8 @@
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