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[09/25] tty: serial: icom: drop uart_port->lock before calling tty_flip_buffer_push()

Message ID b7821cdba5d1c093a168812ec51cd940eb46513e.1376651114.git.viresh.kumar@linaro.org
State New
Headers show

Commit Message

Viresh Kumar Aug. 16, 2013, 11:43 a.m. UTC 
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@linutronix.de>
Date:   Tue May 29 21:53:50 2007 +0100

    [ARM] 4417/1: Serial: Fix AMBA drivers locking

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/tty/serial/icom.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/drivers/tty/serial/icom.c b/drivers/tty/serial/icom.c
index 18ed5ae..46cb597 100644
--- a/drivers/tty/serial/icom.c
+++ b/drivers/tty/serial/icom.c
@@ -834,7 +834,10 @@  ignore_char:
 		status = cpu_to_le16(icom_port->statStg->rcv[rcv_buff].flags);
 	}
 	icom_port->next_rcv = rcv_buff;
+
+	spin_unlock(&icom_port->uart_port.lock);
 	tty_flip_buffer_push(port);
+	spin_lock(&icom_port->uart_port.lock);
 }
 
 static void process_interrupt(u16 port_int_reg,