Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched

[linux-2.6-omap-h63xx.git] / drivers / mmc / card / sdio_uart.c

diff --git a/drivers/mmc/card/sdio_uart.c b/drivers/mmc/card/sdio_uart.c
index 606100212afa72da532629cd6f845d6a3454d22d..d552de6831108cac25d7981a0e608940eb5cad3d 100644 (file)
--- a/drivers/mmc/card/sdio_uart.c
+++ b/drivers/mmc/card/sdio_uart.c
@@ -79,6 +79,7 @@ struct sdio_uart_port {
        struct mutex            open_lock;
        struct sdio_func        *func;
        struct mutex            func_lock;
+       struct task_struct      *in_sdio_uart_irq;
        unsigned int            regs_offset;
        struct circ_buf         xmit;
        spinlock_t              write_lock;
@@ -186,14 +187,16 @@ static int sdio_uart_claim_func(struct sdio_uart_port *port)
                mutex_unlock(&port->func_lock);
                return -ENODEV;
        }
-       sdio_claim_host(port->func);
+       if (likely(port->in_sdio_uart_irq != current))
+               sdio_claim_host(port->func);
        mutex_unlock(&port->func_lock);
        return 0;
 }
 
 static inline void sdio_uart_release_func(struct sdio_uart_port *port)
 {
-       sdio_release_host(port->func);
+       if (likely(port->in_sdio_uart_irq != current))
+               sdio_release_host(port->func);
 }
 
 static inline unsigned int sdio_in(struct sdio_uart_port *port, int offset)
@@ -511,15 +514,29 @@ static void sdio_uart_irq(struct sdio_func *func)
        struct sdio_uart_port *port = sdio_get_drvdata(func);
        unsigned int iir, lsr;
 
+       /*
+        * In a few places sdio_uart_irq() is called directly instead of
+        * waiting for the actual interrupt to be raised and the SDIO IRQ
+        * thread scheduled in order to reduce latency.  However, some
+        * interaction with the tty core may end up calling us back
+        * (serial echo, flow control, etc.) through those same places
+        * causing undesirable effects.  Let's stop the recursion here.
+        */
+       if (unlikely(port->in_sdio_uart_irq == current))
+               return;
+
        iir = sdio_in(port, UART_IIR);
        if (iir & UART_IIR_NO_INT)
                return;
+
+       port->in_sdio_uart_irq = current;
        lsr = sdio_in(port, UART_LSR);
        if (lsr & UART_LSR_DR)
                sdio_uart_receive_chars(port, &lsr);
        sdio_uart_check_modem_status(port);
        if (lsr & UART_LSR_THRE)
                sdio_uart_transmit_chars(port);
+       port->in_sdio_uart_irq = NULL;
 }
 
 static int sdio_uart_startup(struct sdio_uart_port *port)