The port lock needs to be dropped across the tty_flip_buffer call, as it
would lead to a deadlock with the spin_lock(&port->lock) in uart_start()
Uncovered by lockdep / preempt-rt
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
Index: linux-2.6.22/drivers/serial/mpc52xx_uart.c
===================================================================
--- linux-2.6.22.orig/drivers/serial/mpc52xx_uart.c 2007-07-09
01:32:17.000000000 +0200
+++ linux-2.6.22/drivers/serial/mpc52xx_uart.c 2007-07-25 21:06:11.000000000
+0200
@@ -501,7 +501,9 @@ mpc52xx_uart_int_rx_chars(struct uart_po
}
}
+ spin_unlock(&port->lock);
tty_flip_buffer_push(tty);
+ spin_lock(&port->lock);
return in_be16(&PSC(port)->mpc52xx_psc_status) & MPC52xx_PSC_SR_RXRDY;
}
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