Fix a potential issue in mpc52xx uart driver

mpc52xx_uart_int and __uart_put_char both try to acquire the
port->lock. Therefore the function sequence of:

mpc52xx_uart_int--> ...-->flush_to_ldisc-->...-->__uart_put_char

can potentially trigger a deadlock. To avoid this deadlock a fix
similar to that found in the 8250.c serial driver is applied. The
deadlock is avoided by releasing the lock before pushing a buffer
and reacquiring it when completed.

Signed-off-by: Andrew Liu <shengping.liu@windriver.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Andrew Liu 2008-04-29 17:36:25 +10:00 коммит произвёл Grant Likely
Родитель 80791be111
Коммит fbe543b412
1 изменённых файлов: 2 добавлений и 0 удалений

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@ -783,7 +783,9 @@ mpc52xx_uart_int_rx_chars(struct uart_port *port)
} }
} }
spin_unlock(&port->lock);
tty_flip_buffer_push(tty); tty_flip_buffer_push(tty);
spin_lock(&port->lock);
return psc_ops->raw_rx_rdy(port); return psc_ops->raw_rx_rdy(port);
} }