The -rt patch triggers a lockdep warning for serial drivers if
tty_flip_buffer_push() is called with uart_port->lock locked. This never shows
up on UP kernels.
Release the port lock before calling tty_flip_buffer_push() and reacquire it
after the call.
Similar stuff was already done for few other drivers in the past, like:
commit 2389b272168ceec056ca1d8a870a97fa9c26e11a
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Tue May 29 21:53:50 2007 +0100
[ARM] 4417/1: Serial: Fix AMBA drivers locking
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
drivers/tty/serial/sa1100.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/serial/sa1100.c b/drivers/tty/serial/sa1100.c
index af6b3e3..28d60ef 100644
--- a/drivers/tty/serial/sa1100.c
+++ b/drivers/tty/serial/sa1100.c
@@ -232,7 +232,10 @@ sa1100_rx_chars(struct sa1100_port *sport)
status = UTSR1_TO_SM(UART_GET_UTSR1(sport)) |
UTSR0_TO_SM(UART_GET_UTSR0(sport));
}
+
+ spin_unlock(&sport->port.lock);
tty_flip_buffer_push(&sport->port.state->port);
+ spin_lock(&sport->port.lock);
}
static void sa1100_tx_chars(struct sa1100_port *sport)
--
1.7.12.rc2.18.g61b472e
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