Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 2274d96..1be8bea 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -106,12 +106,8 @@
int usb_serial_generic_open(struct tty_struct *tty, struct usb_serial_port *port)
{
int result = 0;
- unsigned long flags;
- spin_lock_irqsave(&port->lock, flags);
- port->throttled = 0;
- port->throttle_req = 0;
- spin_unlock_irqrestore(&port->lock, flags);
+ clear_bit(USB_SERIAL_THROTTLED, &port->flags);
if (port->bulk_in_size)
result = usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
@@ -375,7 +371,7 @@
{
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;
@@ -383,42 +379,55 @@
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();
-resubmit:
- /* Throttle the device if requested by tty */
- spin_lock_irqsave(&port->lock, flags);
- port->throttled = port->throttle_req;
- if (!port->throttled) {
- spin_unlock_irqrestore(&port->lock, flags);
- usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC);
- } else {
- spin_unlock_irqrestore(&port->lock, flags);
- }
+ if (stopped)
+ return;
+
+ if (test_bit(USB_SERIAL_THROTTLED, &port->flags))
+ return;
+
+ usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);
@@ -454,10 +463,9 @@
default:
dev_err_console(port, "%s - nonzero urb status: %d\n",
__func__, status);
- goto resubmit;
+ break;
}
-resubmit:
usb_serial_generic_write_start(port, GFP_ATOMIC);
usb_serial_port_softint(port);
}
@@ -466,26 +474,24 @@
void usb_serial_generic_throttle(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
- unsigned long flags;
- spin_lock_irqsave(&port->lock, flags);
- port->throttle_req = 1;
- spin_unlock_irqrestore(&port->lock, flags);
+ set_bit(USB_SERIAL_THROTTLED, &port->flags);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_throttle);
void usb_serial_generic_unthrottle(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
- int was_throttled;
- spin_lock_irq(&port->lock);
- was_throttled = port->throttled;
- port->throttled = port->throttle_req = 0;
- spin_unlock_irq(&port->lock);
+ clear_bit(USB_SERIAL_THROTTLED, &port->flags);
- if (was_throttled)
- usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
+ /*
+ * Matches the smp_mb__after_atomic() in
+ * usb_serial_generic_read_bulk_callback().
+ */
+ smp_mb();
+
+ usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_unthrottle);