From: Andrew Liu <shengping.liu@windriver•com>
To: grant.likely@secretlab•ca, tnt@246tnt•com
Cc: linuxppc-dev <linuxppc-dev@ozlabs•org>
Subject: [PATCH] Fix a potential issue in mpc52xx uart driver
Date: Tue, 29 Apr 2008 16:36:25 +0900 [thread overview]
Message-ID: <4816CFF9.5030505@windriver.com> (raw)
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>
diff --git a/drivers/serial/mpc52xx_uart.c b/drivers/serial/mpc52xx_uart.c
index d93b357..5f95e53 100644
--- a/drivers/serial/mpc52xx_uart.c
+++ b/drivers/serial/mpc52xx_uart.c
@@ -783,7 +783,9 @@ mpc52xx_uart_int_rx_chars(struct uart_port *port)
}
}
+ spin_unlock(&port->lock);
tty_flip_buffer_push(tty);
+ spin_lock(&port->lock);
return psc_ops->raw_rx_rdy(port);
}
next reply other threads:[~2008-04-29 17:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-29 7:36 Andrew Liu [this message]
2008-05-01 18:07 ` [PATCH] Fix a potential issue in mpc52xx uart driver Grant Likely
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