Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Fri, 18 Aug 2017 14:13:13 +0100 | Subject | [PATCH 3.2 09/59] serial: sh-sci: Fix panic when serial console and DMA are enabled |
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3.2.92-rc1 review patch. If anyone has any objections, please let me know.
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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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