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    Subject[PATCH 3.2 09/59] serial: sh-sci: Fix panic when serial console and DMA are enabled
    3.2.92-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>

    commit 3c9101766b502a0163d1d437fada5801cf616be2 upstream.

    This patch fixes an issue that kernel panic happens when DMA is enabled
    and we press enter key while the kernel booting on the serial console.

    * An interrupt may occur after sci_request_irq().
    * DMA transfer area is initialized by setup_timer() in sci_request_dma()
    and used in interrupt.

    If an interrupt occurred between sci_request_irq() and setup_timer() in
    sci_request_dma(), DMA transfer area has not been initialized yet.
    So, this patch changes the order of sci_request_irq() and
    sci_request_dma().

    Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
    Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>
    [Shimoda changes the commit log]
    Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    [bwh: Backported to 3.2: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/tty/serial/sh-sci.c | 10 ++++++----
    1 file changed, 6 insertions(+), 4 deletions(-)

    --- a/drivers/tty/serial/sh-sci.c
    +++ b/drivers/tty/serial/sh-sci.c
    @@ -1579,11 +1579,13 @@ static int sci_startup(struct uart_port

    sci_port_enable(s);

    + sci_request_dma(port);
    +
    ret = sci_request_irq(s);
    - if (unlikely(ret < 0))
    + if (unlikely(ret < 0)) {
    + sci_free_dma(port);
    return ret;
    -
    - sci_request_dma(port);
    + }

    sci_start_tx(port);
    sci_start_rx(port);
    @@ -1600,8 +1602,8 @@ static void sci_shutdown(struct uart_por
    sci_stop_rx(port);
    sci_stop_tx(port);

    - sci_free_dma(port);
    sci_free_irq(s);
    + sci_free_dma(port);

    sci_port_disable(s);
    }
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