In a multithreaded scenario a flush() and a write() may be waiting for the same
IO to complete. Hence completion of output must use wake_up_all(),
even in error handling, while a flush may be waiting for an intended but
not started Io.
Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
---
drivers/usb/class/cdc-wdm.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index e3db6fbeadef..adb3fc307083 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -151,7 +151,7 @@ static void wdm_out_callback(struct urb *urb)
kfree(desc->outbuf);
desc->outbuf = NULL;
clear_bit(WDM_IN_USE, &desc->flags);
- wake_up(&desc->wait);
+ wake_up_all(&desc->wait);
}
static void wdm_in_callback(struct urb *urb)
@@ -424,6 +424,7 @@ static ssize_t wdm_write
if (rv < 0) {
desc->outbuf = NULL;
clear_bit(WDM_IN_USE, &desc->flags);
+ wake_up_all(&desc->wait); /* for flush() */
dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
rv = usb_translate_errors(rv);
goto out_free_mem_pm;
@@ -586,6 +587,7 @@ static ssize_t wdm_read
static int wdm_flush(struct file *file, fl_owner_t id)
{
struct wdm_device *desc = file->private_data;
+ int rv;
wait_event(desc->wait,
/*
@@ -600,11 +602,12 @@ static int wdm_flush(struct file *file, fl_owner_t id)
/* cannot dereference desc->intf if WDM_DISCONNECTING */
if (test_bit(WDM_DISCONNECTING, &desc->flags))
return -ENODEV;
- if (desc->werr < 0)
+ rv = desc->werr;
+ if (rv < 0)
dev_err(&desc->intf->dev, "Error in flush path: %d\n",
- desc->werr);
+ rv);
- return usb_translate_errors(desc->werr);
+ return usb_translate_errors(rv);
}
static __poll_t wdm_poll(struct file *file, struct poll_table_struct *wait)
--
2.16.4
