serial8250_rx_chars() must be called from interrupt context and with
the port lock held. The port lock is released temporarily within that
function to call tty_flip_buffer_push(). However, there may be other
drivers that need to synchronize the tty_flip_buffer_push() call within
serial8250_rx_chars() with other contexts. Since the port lock cannot
be used for this synchronization, an optional spinlock argument is added.
If non-NULL, this will be locked during the tty_flip_buffer_push() call.
Signed-off-by: John Ogness <john.ogn...@linutronix.de>
---
patch against next-20160122
drivers/tty/serial/8250/8250_fsl.c | 2 +-
drivers/tty/serial/8250/8250_omap.c | 2 +-
drivers/tty/serial/8250/8250_port.c | 9 +++++++--
include/linux/serial_8250.h | 3 ++-
4 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_fsl.c
b/drivers/tty/serial/8250/8250_fsl.c
index 910bfee..790868d 100644
--- a/drivers/tty/serial/8250/8250_fsl.c
+++ b/drivers/tty/serial/8250/8250_fsl.c
@@ -49,7 +49,7 @@ int fsl8250_handle_irq(struct uart_port *port)
lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR);
if (lsr & (UART_LSR_DR | UART_LSR_BI))
- lsr = serial8250_rx_chars(up, lsr);
+ lsr = serial8250_rx_chars(up, lsr, NULL);
serial8250_modem_status(up);
diff --git a/drivers/tty/serial/8250/8250_omap.c
b/drivers/tty/serial/8250/8250_omap.c
index a2c0734..6cf3b4f 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1024,7 +1024,7 @@ static int omap_8250_dma_handle_irq(struct uart_port
*port)
dma_err = omap_8250_rx_dma(up, iir);
if (dma_err) {
- status = serial8250_rx_chars(up, status);
+ status = serial8250_rx_chars(up, status, NULL);
omap_8250_rx_dma(up, 0);
}
}
diff --git a/drivers/tty/serial/8250/8250_port.c
b/drivers/tty/serial/8250/8250_port.c
index 8d262bc..e838115 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1418,7 +1418,8 @@ static void serial8250_enable_ms(struct uart_port *port)
* by this Rx routine.
*/
unsigned char
-serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
+serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr,
+ spinlock_t *flip_lock)
{
struct uart_port *port = &up->port;
unsigned char ch;
@@ -1485,7 +1486,11 @@ ignore_char:
lsr = serial_in(up, UART_LSR);
} while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (--max_count > 0));
spin_unlock(&port->lock);
+ if (flip_lock)
+ spin_lock(flip_lock);
tty_flip_buffer_push(&port->state->port);
+ if (flip_lock)
+ spin_unlock(flip_lock);
spin_lock(&port->lock);
return lsr;
}
@@ -1591,7 +1596,7 @@ int serial8250_handle_irq(struct uart_port *port,
unsigned int iir)
dma_err = up->dma->rx_dma(up, iir);
if (!up->dma || dma_err)
- status = serial8250_rx_chars(up, status);
+ status = serial8250_rx_chars(up, status, NULL);
}
serial8250_modem_status(up);
if ((!up->dma || (up->dma && up->dma->tx_err)) &&
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index faa0e03..9c814e3 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -147,7 +147,8 @@ extern void serial8250_do_pm(struct uart_port *port,
unsigned int state,
extern void serial8250_do_set_mctrl(struct uart_port *port, unsigned int
mctrl);
extern int fsl8250_handle_irq(struct uart_port *port);
int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
-unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char
lsr);
+unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr,
+ spinlock_t *flip_lock);
void serial8250_tx_chars(struct uart_8250_port *up);
unsigned int serial8250_modem_status(struct uart_8250_port *up);
void serial8250_init_port(struct uart_8250_port *up);
--
1.7.10.4
