diff options
-rw-r--r-- | drivers/usb/serial/generic.c | 39 |
1 files changed, 32 insertions, 7 deletions
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index a648fdca938a..0036d9627787 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -350,6 +350,7 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb) struct usb_serial_port *port = urb->context; unsigned char *data = urb->transfer_buffer; unsigned long flags; + bool stopped = false; int status = urb->status; int i; @@ -357,33 +358,51 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb) if (urb == port->read_urbs[i]) break; } - set_bit(i, &port->read_urbs_free); dev_dbg(&port->dev, "%s - urb %d, len %d\n", __func__, i, urb->actual_length); switch (status) { case 0: + usb_serial_debug_data(&port->dev, __func__, urb->actual_length, + data); + port->serial->type->process_read_urb(urb); break; case -ENOENT: case -ECONNRESET: case -ESHUTDOWN: dev_dbg(&port->dev, "%s - urb stopped: %d\n", __func__, status); - return; + stopped = true; + break; case -EPIPE: dev_err(&port->dev, "%s - urb stopped: %d\n", __func__, status); - return; + stopped = true; + break; default: dev_dbg(&port->dev, "%s - nonzero urb status: %d\n", __func__, status); - goto resubmit; + break; } - usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data); - port->serial->type->process_read_urb(urb); + /* + * Make sure URB processing is done before marking as free to avoid + * racing with unthrottle() on another CPU. Matches the barriers + * implied by the test_and_clear_bit() in + * usb_serial_generic_submit_read_urb(). + */ + smp_mb__before_atomic(); + set_bit(i, &port->read_urbs_free); + /* + * Make sure URB is marked as free before checking the throttled flag + * to avoid racing with unthrottle() on another CPU. Matches the + * smp_mb() in unthrottle(). + */ + smp_mb__after_atomic(); + + if (stopped) + return; -resubmit: /* Throttle the device if requested by tty */ spin_lock_irqsave(&port->lock, flags); port->throttled = port->throttle_req; @@ -458,6 +477,12 @@ void usb_serial_generic_unthrottle(struct tty_struct *tty) port->throttled = port->throttle_req = 0; spin_unlock_irq(&port->lock); + /* + * Matches the smp_mb__after_atomic() in + * usb_serial_generic_read_bulk_callback(). + */ + smp_mb(); + if (was_throttled) usb_serial_generic_submit_read_urbs(port, GFP_KERNEL); } |