Hi Alexandre,

Thanks for the patch.

On 04/25/2017 08:19 AM, Alexandre Courbot wrote:
> v4l2_m2m_job_finish(), which is called from the interrupt handler with
> slock acquired, can call the device_run() hook immediately if another
> context was in the queue. This hook also acquires slock, resulting in
> a deadlock for this scenario.
> 
> Fix this by releasing slock right before calling v4l2_m2m_job_finish().
> This is safe to do as the state of the hardware cannot change before
> v4l2_m2m_job_finish() is called anyway.
> 
> Signed-off-by: Alexandre Courbot <acour...@chromium.org>
> ---
>  drivers/media/platform/s5p-jpeg/jpeg-core.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/s5p-jpeg/jpeg-core.c 
> b/drivers/media/platform/s5p-jpeg/jpeg-core.c
> index 52dc7941db65..223b4379929e 100644
> --- a/drivers/media/platform/s5p-jpeg/jpeg-core.c
> +++ b/drivers/media/platform/s5p-jpeg/jpeg-core.c
> @@ -2642,13 +2642,13 @@ static irqreturn_t s5p_jpeg_irq(int irq, void *dev_id)
>       if (curr_ctx->mode == S5P_JPEG_ENCODE)
>               vb2_set_plane_payload(&dst_buf->vb2_buf, 0, payload_size);
>       v4l2_m2m_buf_done(dst_buf, state);
> -     v4l2_m2m_job_finish(jpeg->m2m_dev, curr_ctx->fh.m2m_ctx);
>  
>       curr_ctx->subsampling = s5p_jpeg_get_subsampling_mode(jpeg->regs);
>       spin_unlock(&jpeg->slock);
>  
>       s5p_jpeg_clear_int(jpeg->regs);
>  
> +     v4l2_m2m_job_finish(jpeg->m2m_dev, curr_ctx->fh.m2m_ctx);
>       return IRQ_HANDLED;
>  }
>  
> @@ -2707,11 +2707,12 @@ static irqreturn_t exynos4_jpeg_irq(int irq, void 
> *priv)
>               v4l2_m2m_buf_done(dst_vb, VB2_BUF_STATE_ERROR);
>       }
>  
> -     v4l2_m2m_job_finish(jpeg->m2m_dev, curr_ctx->fh.m2m_ctx);
>       if (jpeg->variant->version == SJPEG_EXYNOS4)
>               curr_ctx->subsampling = exynos4_jpeg_get_frame_fmt(jpeg->regs);
>  
>       spin_unlock(&jpeg->slock);
> +
> +     v4l2_m2m_job_finish(jpeg->m2m_dev, curr_ctx->fh.m2m_ctx);
>       return IRQ_HANDLED;
>  }
>  
> @@ -2770,10 +2771,15 @@ static irqreturn_t exynos3250_jpeg_irq(int irq, void 
> *dev_id)
>       if (curr_ctx->mode == S5P_JPEG_ENCODE)
>               vb2_set_plane_payload(&dst_buf->vb2_buf, 0, payload_size);
>       v4l2_m2m_buf_done(dst_buf, state);
> -     v4l2_m2m_job_finish(jpeg->m2m_dev, curr_ctx->fh.m2m_ctx);
>  
>       curr_ctx->subsampling =
>                       exynos3250_jpeg_get_subsampling_mode(jpeg->regs);
> +
> +     spin_unlock(&jpeg->slock);
> +
> +     v4l2_m2m_job_finish(jpeg->m2m_dev, curr_ctx->fh.m2m_ctx);
> +     return IRQ_HANDLED;
> +
>  exit_unlock:
>       spin_unlock(&jpeg->slock);
>       return IRQ_HANDLED;
> 

Acked-by: Jacek Anaszewski <jacek.anaszew...@gmail.com>

Just out of curiosity - could you share how you discovered the problem -
by some static checkers or trying to use the driver?

-- 
Best regards,
Jacek Anaszewski

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