Writing to ttyGS unconnected to host currently fills port_write_buf
which then causes gs_write_room to return 0 and boot hangs waiting
for connection.
Fix that by dropping previsous data if free space in port_write_buf
reaches treshold and host is unconnected.
Signed-off-by: Ladislav Michl <la...@linux-mips.org>
---
Changes:
- v2: New patch
drivers/usb/gadget/function/u_serial.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/gadget/function/u_serial.c
b/drivers/usb/gadget/function/u_serial.c
index 558a6929ce68..2dd6e1211d4a 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -79,6 +79,7 @@
*/
#define QUEUE_SIZE 16
#define WRITE_BUF_SIZE 8192 /* TX only */
+#define WRITE_BUF_TRESHOLD 1024
#define GS_CONSOLE_BUF_SIZE 8192
/* console info */
@@ -562,7 +563,7 @@ static int gs_start_io(struct gs_port *port)
/* unblock any pending writes into our circular buffer */
if (started) {
- tty_wakeup(port->port.tty);
+ gs_start_tx(port);
} else {
gs_free_requests(ep, head, &port->read_allocated);
gs_free_requests(port->port_usb->in, &port->write_pool,
@@ -758,6 +759,7 @@ static int gs_write(struct tty_struct *tty, const unsigned
char *buf, int count)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
+ int avail, cnt;
pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
port->port_num, tty, count);
@@ -766,8 +768,16 @@ static int gs_write(struct tty_struct *tty, const unsigned
char *buf, int count)
if (count)
count = kfifo_in(&port->port_write_buf, buf, count);
/* treat count == 0 as flush_chars() */
- if (port->port_usb)
+ if (port->port_usb) {
gs_start_tx(port);
+ } else {
+ avail = kfifo_avail(&port->port_write_buf);
+ if (avail < WRITE_BUF_TRESHOLD) {
+ cnt = WRITE_BUF_TRESHOLD - avail;
+ while (cnt--)
+ kfifo_skip(&port->port_write_buf);
+ }
+ }
spin_unlock_irqrestore(&port->port_lock, flags);
return count;
@@ -784,6 +794,9 @@ static int gs_put_char(struct tty_struct *tty, unsigned
char ch)
spin_lock_irqsave(&port->port_lock, flags);
status = kfifo_put(&port->port_write_buf, ch);
+ if (!port->port_usb &&
+ kfifo_avail(&port->port_write_buf) < WRITE_BUF_TRESHOLD)
+ kfifo_skip(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
return status;
@@ -799,6 +812,8 @@ static void gs_flush_chars(struct tty_struct *tty)
spin_lock_irqsave(&port->port_lock, flags);
if (port->port_usb)
gs_start_tx(port);
+ else
+ kfifo_reset_out(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
}
@@ -806,11 +821,10 @@ static int gs_write_room(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
- int room = 0;
+ int room;
spin_lock_irqsave(&port->port_lock, flags);
- if (port->port_usb)
- room = kfifo_avail(&port->port_write_buf);
+ room = kfifo_avail(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
@@ -823,7 +837,7 @@ static int gs_chars_in_buffer(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
- int chars = 0;
+ int chars;
spin_lock_irqsave(&port->port_lock, flags);
chars = kfifo_len(&port->port_write_buf);
--
2.22.0
