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SubjectRe: [PATCH AUTOSEL 4.18 27/48] sound: enable interrupt after dma buffer initialization
On Fri, Oct 05, 2018 at 12:14:03PM -0400, Sasha Levin wrote:
> From: Yu Zhao <yuzhao@google.com>
>
> [ Upstream commit b61749a89f826eb61fc59794d9e4697bd246eb61 ]
>
> In snd_hdac_bus_init_chip(), we enable interrupt before
> snd_hdac_bus_init_cmd_io() initializing dma buffers. If irq has
> been acquired and irq handler uses the dma buffer, kernel may crash
> when interrupt comes in.

CCing Takashi who's the maintainer here for review.

>
> Fix the problem by postponing enabling irq after dma buffer
> initialization. And warn once on null dma buffer pointer during the
> initialization.
>
> Reviewed-by: Takashi Iwai <tiwai@suse.de>
> Signed-off-by: Yu Zhao <yuzhao@google.com>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
> ---
> sound/hda/hdac_controller.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/sound/hda/hdac_controller.c b/sound/hda/hdac_controller.c
> index 560ec0986e1a..11057d9f84ec 100644
> --- a/sound/hda/hdac_controller.c
> +++ b/sound/hda/hdac_controller.c
> @@ -40,6 +40,8 @@ static void azx_clear_corbrp(struct hdac_bus *bus)
> */
> void snd_hdac_bus_init_cmd_io(struct hdac_bus *bus)
> {
> + WARN_ON_ONCE(!bus->rb.area);
> +
> spin_lock_irq(&bus->reg_lock);
> /* CORB set up */
> bus->corb.addr = bus->rb.addr;
> @@ -479,13 +481,15 @@ bool snd_hdac_bus_init_chip(struct hdac_bus *bus, bool full_reset)
> /* reset controller */
> azx_reset(bus, full_reset);
>
> - /* initialize interrupts */
> + /* clear interrupts */
> azx_int_clear(bus);
> - azx_int_enable(bus);
>
> /* initialize the codec command I/O */
> snd_hdac_bus_init_cmd_io(bus);
>
> + /* enable interrupts after CORB/RIRB buffers are initialized above */
> + azx_int_enable(bus);
> +
> /* program the position buffer */
> if (bus->use_posbuf && bus->posbuf.addr) {
> snd_hdac_chip_writel(bus, DPLBASE, (u32)bus->posbuf.addr);
> --
> 2.17.1
>
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