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/netx-serial.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/netx-serial.c b/drivers/tty/serial/netx-serial.c
index b9a40ed..4f59c4d 100644
--- a/drivers/tty/serial/netx-serial.c
+++ b/drivers/tty/serial/netx-serial.c
@@ -196,7 +196,7 @@ static void netx_txint(struct uart_port *port)
uart_write_wakeup(port);
}
-static void netx_rxint(struct uart_port *port)
+static void netx_rxint(struct uart_port *port, unsigned long *flags)
{
unsigned char rx, flg, status;
@@ -236,7 +236,9 @@ static void netx_rxint(struct uart_port *port)
uart_insert_char(port, status, SR_OE, rx, flg);
}
+ spin_unlock_irqrestore(&port->lock, *flags);
tty_flip_buffer_push(&port->state->port);
+ spin_lock_irqsave(&port->lock, *flags);
}
static irqreturn_t netx_int(int irq, void *dev_id)
@@ -250,7 +252,7 @@ static irqreturn_t netx_int(int irq, void *dev_id)
status = readl(port->membase + UART_IIR) & IIR_MASK;
while (status) {
if (status & IIR_RIS)
- netx_rxint(port);
+ netx_rxint(port, &flags);
if (status & IIR_TIS)
netx_txint(port);
if (status & IIR_MIS) {
--
1.7.12.rc2.18.g61b472e
--
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