The patch titled
serial: mcf: don't take spinlocks in already protected functions
has been added to the -mm tree. Its filename is
serial-mcf-dont-take-spinlocks-in-already-protected-functions.patch
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See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: serial: mcf: don't take spinlocks in already protected functions
From: Yury Georgievskiy <ygeorgie@xxxxxxxxx>
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.
Signed-off-by: Yury Georgievskiy <ygeorgie@xxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/serial/mcf.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
diff -puN drivers/serial/mcf.c~serial-mcf-dont-take-spinlocks-in-already-protected-functions drivers/serial/mcf.c
--- a/drivers/serial/mcf.c~serial-mcf-dont-take-spinlocks-in-already-protected-functions
+++ a/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);
}
/****************************************************************************/
@@ -368,11 +354,15 @@ static irqreturn_t mcf_interrupt(int irq
unsigned int isr;
isr = readb(port->membase + MCFUART_UISR) & pp->imr;
+
+ spin_lock(&port->lock);
if (isr & MCFUART_UIR_RXREADY)
mcf_rx_chars(pp);
if (isr & MCFUART_UIR_TXREADY)
mcf_tx_chars(pp);
- return IRQ_HANDLED;
+ spin_unlock(&port->lock);
+
+ return IRQ_RETVAL(isr);
}
/****************************************************************************/
_
Patches currently in -mm which might be from ygeorgie@xxxxxxxxx are
serial-mcf-dont-take-spinlocks-in-already-protected-functions.patch
serial-mcf-dont-take-spinlocks-in-already-protected-functions-fix.patch
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