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From akpm@linux-foundation.org Thu Jul 22 15:55:47 2010
Message-Id: <201007202226.o6KMQpNm021530@imap1.linux-foundation.org>
Subject: serial: mcf: don't take spinlocks in already protected functions
To: greg@kroah.com
Cc: linux-serial@vger.kernel.org, akpm@linux-foundation.org,
ygeorgie@gmail.com, alan@lxorguk.ukuu.org.uk, gerg@uclinux.org
From: akpm@linux-foundation.org
Date: Tue, 20 Jul 2010 15:26:50 -0700
From: Yury Georgievskiy <ygeorgie@gmail.com>
Don't take the port spinlock in uart functions where the serial core
already takes care of locking/unlocking them.
The code would actually lock up on architectures where spinlocks are
implemented.
Also protect calling mcf_rx_chars/mcf_tx_chars in the interrupt handler by
the port spinlock and use IRQ_RETVAL to return from isr.
[akpm@linux-foundation.org: make irq-handler return value more explicit]
Signed-off-by: Yury Georgievskiy <ygeorgie@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/serial/mcf.c | 31 +++++++++++++------------------
1 file changed, 13 insertions(+), 18 deletions(-)
--- a/drivers/serial/mcf.c
+++ b/drivers/serial/mcf.c
@@ -70,16 +70,14 @@ static unsigned int mcf_tx_empty(struct
static unsigned int mcf_get_mctrl(struct uart_port *port)
{
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
- unsigned long flags;
unsigned int sigs;
- spin_lock_irqsave(&port->lock, flags);
sigs = (readb(port->membase + MCFUART_UIPR) & MCFUART_UIPR_CTS) ?
0 : TIOCM_CTS;
sigs |= (pp->sigs & TIOCM_RTS);
sigs |= (mcf_getppdcd(port->line) ? TIOCM_CD : 0);
sigs |= (mcf_getppdtr(port->line) ? TIOCM_DTR : 0);
- spin_unlock_irqrestore(&port->lock, flags);
+
return sigs;
}
@@ -88,16 +86,13 @@ static unsigned int mcf_get_mctrl(struct
static void mcf_set_mctrl(struct uart_port *port, unsigned int sigs)
{
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
- unsigned long flags;
- spin_lock_irqsave(&port->lock, flags);
pp->sigs = sigs;
mcf_setppdtr(port->line, (sigs & TIOCM_DTR));
if (sigs & TIOCM_RTS)
writeb(MCFUART_UOP_RTS, port->membase + MCFUART_UOP1);
else
writeb(MCFUART_UOP_RTS, port->membase + MCFUART_UOP0);
- spin_unlock_irqrestore(&port->lock, flags);
}
/****************************************************************************/
@@ -105,12 +100,9 @@ static void mcf_set_mctrl(struct uart_po
static void mcf_start_tx(struct uart_port *port)
{
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
- unsigned long flags;
- spin_lock_irqsave(&port->lock, flags);
pp->imr |= MCFUART_UIR_TXREADY;
writeb(pp->imr, port->membase + MCFUART_UIMR);
- spin_unlock_irqrestore(&port->lock, flags);
}
/****************************************************************************/
@@ -118,12 +110,9 @@ static void mcf_start_tx(struct uart_por
static void mcf_stop_tx(struct uart_port *port)
{
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
- unsigned long flags;
- spin_lock_irqsave(&port->lock, flags);
pp->imr &= ~MCFUART_UIR_TXREADY;
writeb(pp->imr, port->membase + MCFUART_UIMR);
- spin_unlock_irqrestore(&port->lock, flags);
}
/****************************************************************************/
@@ -131,12 +120,9 @@ static void mcf_stop_tx(struct uart_port
static void mcf_stop_rx(struct uart_port *port)
{
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
- unsigned long flags;
- spin_lock_irqsave(&port->lock, flags);
pp->imr &= ~MCFUART_UIR_RXREADY;
writeb(pp->imr, port->membase + MCFUART_UIMR);
- spin_unlock_irqrestore(&port->lock, flags);
}
/****************************************************************************/
@@ -366,13 +352,22 @@ static irqreturn_t mcf_interrupt(int irq
struct uart_port *port = data;
struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
unsigned int isr;
+ irqreturn_t ret = IRQ_NONE;
isr = readb(port->membase + MCFUART_UISR) & pp->imr;
- if (isr & MCFUART_UIR_RXREADY)
+
+ spin_lock(&port->lock);
+ if (isr & MCFUART_UIR_RXREADY) {
mcf_rx_chars(pp);
- if (isr & MCFUART_UIR_TXREADY)
+ ret = IRQ_HANDLED;
+ }
+ if (isr & MCFUART_UIR_TXREADY) {
mcf_tx_chars(pp);
- return IRQ_HANDLED;
+ ret = IRQ_HANDLED;
+ }
+ spin_unlock(&port->lock);
+
+ return ret;
}
/****************************************************************************/
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