[PATCH v2 2/2] hso: fix deadlock when receiving bursts of data
From: Olivier Sobrie <hidden>
Date: 2014-07-11 13:06:48
Also in:
lkml
Subsystem:
hso 3g modem driver, networking drivers, the rest, usb networking drivers · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
When the module sends bursts of data, sometimes a deadlock happens in the hso driver when the tty buffer doesn't get the chance to be flushed quickly enough. Remove the endless while loop in function put_rxbuf_data() which is called by the urb completion handler. If there isn't enough room in the tty buffer, discards all the data received in the URB. Cc: David Miller <davem@davemloft.net> Cc: David Laight <redacted> Cc: One Thousand Gnomes <redacted> Cc: Dan Williams <redacted> Cc: Jan Dumon <redacted> Signed-off-by: Olivier Sobrie <redacted> --- Changes in v2: - remove the unthrottle timer added in the previous patch version - drop entire rx urb data if there is not enough space in tty buffer - remove variable curr_rx_urb_offset from hso_serial structure drivers/net/usb/hso.c | 38 +++++++++++++++++--------------------- 1 file changed, 17 insertions(+), 21 deletions(-)
diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 9ca2b41..a4272ed 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c@@ -258,7 +258,6 @@ struct hso_serial { * so as not to drop characters on the floor. */ int curr_rx_urb_idx; - u16 curr_rx_urb_offset; u8 rx_urb_filled[MAX_RX_URBS]; struct tasklet_struct unthrottle_tasklet; };
@@ -2001,8 +2000,7 @@ static void ctrl_callback(struct urb *urb) static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial) { struct tty_struct *tty; - int write_length_remaining = 0; - int curr_write_len; + int count; /* Sanity check */ if (urb == NULL || serial == NULL) {
@@ -2012,29 +2010,28 @@ static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial) tty = tty_port_tty_get(&serial->port); + if (tty && test_bit(TTY_THROTTLED, &tty->flags)) { + tty_kref_put(tty); + return -1; + } + /* Push data to tty */ - write_length_remaining = urb->actual_length - - serial->curr_rx_urb_offset; D1("data to push to tty"); - while (write_length_remaining) { - if (tty && test_bit(TTY_THROTTLED, &tty->flags)) { - tty_kref_put(tty); - return -1; - } - curr_write_len = tty_insert_flip_string(&serial->port, - urb->transfer_buffer + serial->curr_rx_urb_offset, - write_length_remaining); - serial->curr_rx_urb_offset += curr_write_len; - write_length_remaining -= curr_write_len; + count = tty_buffer_request_room(&serial->port, urb->actual_length); + if (count >= urb->actual_length) { + tty_insert_flip_string(&serial->port, urb->transfer_buffer, + urb->actual_length); tty_flip_buffer_push(&serial->port); + } else { + dev_warn(&serial->parent->usb->dev, + "dropping data, %d bytes lost\n", urb->actual_length); } + tty_kref_put(tty); - if (write_length_remaining == 0) { - serial->curr_rx_urb_offset = 0; - serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 0; - } - return write_length_remaining; + serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 0; + + return 0; }
@@ -2205,7 +2202,6 @@ static int hso_stop_serial_device(struct hso_device *hso_dev) } } serial->curr_rx_urb_idx = 0; - serial->curr_rx_urb_offset = 0; if (serial->tx_urb) usb_kill_urb(serial->tx_urb);
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1.7.9.5