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/samsung.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 376079b..275e3e0 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -249,6 +249,8 @@ s3c24xx_serial_rx_chars(int irq, void *dev_id)
ufcon |= S3C2410_UFCON_RESETRX;
wr_regl(port, S3C2410_UFCON, ufcon);
rx_enabled(port) = 1;
+ spin_unlock_irqrestore(&port->lock,
+ flags);
goto out;
}
continue;
@@ -297,10 +299,11 @@ s3c24xx_serial_rx_chars(int irq, void *dev_id)
ignore_char:
continue;
}
+
+ spin_unlock_irqrestore(&port->lock, flags);
tty_flip_buffer_push(&port->state->port);
out:
- spin_unlock_irqrestore(&port->lock, flags);
return IRQ_HANDLED;
}
--
1.7.12.rc2.18.g61b472e
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