Hi all:
When tty->low_latency = 1, tty_flip_buffer_push() may sleep in
tasklet context which will lead to a kernel crash.I think we should
use workqueue instead of tasklet in gs_rx_push() in u_serial.c. Here
is the patch. It works fine.
--- a/drivers/usb/gadget/u_serial.c 2010-01-19 02:23:35.000000000 +0800
+++ b/drivers/usb/gadget/u_serial.c 2010-01-20 14:42:17.000000000 +0800
@@ -105,7 +105,7 @@ struct gs_port {
struct list_head read_pool;
struct list_head read_queue;
unsigned n_read;
- struct tasklet_struct push;
+ struct work_struct push;
struct list_head write_pool;
struct gs_buf port_write_buf;
@@ -464,9 +464,9 @@ __acquires(&port->port_lock)
* So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
* can be buffered before the TTY layer's buffers (currently 64 KB).
*/
-static void gs_rx_push(unsigned long _port)
+static void gs_rx_push(struct work_struct *work)
{
- struct gs_port *port = (void *)_port;
+ struct gs_port *port = container_of(work, struct gs_port, push);
struct tty_struct *tty;
struct list_head *queue = &port->read_queue;
bool disconnect = false;
@@ -560,7 +560,7 @@ recycle:
if (!list_empty(queue) && tty) {
if (!test_bit(TTY_THROTTLED, &tty->flags)) {
if (do_push)
- tasklet_schedule(&port->push);
+ schedule_work(&port->push);
else
pr_warning(PREFIX "%d: RX not scheduled?\n",
port->port_num);
@@ -581,7 +581,7 @@ static void gs_read_complete(struct usb_
/* Queue all received data until the tty layer is ready for it. */
spin_lock(&port->port_lock);
list_add_tail(&req->list, &port->read_queue);
- tasklet_schedule(&port->push);
+ schedule_work(&port->push);
spin_unlock(&port->port_lock);
}
@@ -975,7 +975,7 @@ static void gs_unthrottle(struct tty_str
* rts/cts, or other handshaking with the host, but if the
* read queue backs up enough we'll be NAKing OUT packets.
*/
- tasklet_schedule(&port->push);
+ schedule_work(&port->push);
pr_vdebug(PREFIX "%d: unthrottle\n", port->port_num);
}
spin_unlock_irqrestore(&port->port_lock, flags);
@@ -1028,7 +1028,7 @@ gs_port_alloc(unsigned port_num, struct
init_waitqueue_head(&port->close_wait);
init_waitqueue_head(&port->drain_wait);
- tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
+ INIT_WORK(&port->push, gs_rx_push);
INIT_LIST_HEAD(&port->read_pool);
INIT_LIST_HEAD(&port->read_queue);
@@ -1182,7 +1182,7 @@ void gserial_cleanup(void)
ports[i].port = NULL;
mutex_unlock(&ports[i].lock);
- tasklet_kill(&port->push);
+ flush_scheduled_work();
/* wait for old opens to finish */
wait_event(port->close_wait, gs_closed(port));
--
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