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From: Alessio Igor Bogani on 13 Mar 2010 12:40
The change_speed() function should be serialized against multiple calls.
Use the cfg_lock mutex to do this.

Signed-off-by: Alessio Igor Bogani <abogani(a)texware.it>
---
drivers/usb/serial/ftdi_sio.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 6af0dfa..830f423 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -91,7 +91,7 @@ struct ftdi_private {
unsigned long tx_outstanding_bytes;
unsigned long tx_outstanding_urbs;
unsigned short max_packet_size;
- struct mutex cfg_lock; /* Avoid mess by parallel calls of config ioctl() */
+ struct mutex cfg_lock; /* Avoid mess by parallel calls of config ioctl() and change_speed() */
};

/* struct ftdi_sio_quirk is used by devices requiring special attention. */
@@ -1272,8 +1272,8 @@ check_and_exit:
(priv->flags & ASYNC_SPD_MASK)) ||
(((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST) &&
(old_priv.custom_divisor != priv->custom_divisor))) {
- mutex_unlock(&priv->cfg_lock);
change_speed(tty, port);
+ mutex_unlock(&priv->cfg_lock);
}
else
mutex_unlock(&priv->cfg_lock);
@@ -2264,9 +2264,11 @@ static void ftdi_set_termios(struct tty_struct *tty,
clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
} else {
/* set the baudrate determined before */
+ mutex_lock(&priv->cfg_lock);
if (change_speed(tty, port))
dev_err(&port->dev, "%s urb failed to set baudrate\n",
__func__);
+ mutex_unlock(&priv->cfg_lock);
/* Ensure RTS and DTR are raised when baudrate changed from 0 */
if (!old_termios || (old_termios->c_cflag & CBAUD) == B0)
set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
--
1.6.3.3

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Prev: [GIT PULL] scheduler fixes
Next: [PATCH v2 1/3] ipmi: Raise precedence of PNP based discovery mechanisms (ACPI, PCI)