On Wed, Apr 26, 2017 at 4:15 AM, Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> wrote: > 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 <acourbot@xxxxxxxxxxxx> >> --- >> 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.anaszewski@xxxxxxxxx> > > Just out of curiosity - could you share how you discovered the problem - > by some static checkers or trying to use the driver? We discovered this issue after adding a new unit test for the jpeg codec in Chromium OS: https://bugs.chromium.org/p/chromium/issues/detail?id=705971 >From what I understand the test spawns different processes that access the codec device concurrently, creating the situation leading to the bug. On a slightly related note, I was thinking whether it would make sense to move the call to v4l2_m2m_job_finish() (and maybe other parts of the current interrupt handler) into a worker or a threaded interrupt handler so as to reduce the time we spend with interrupts disabled. Can I have your input on this idea?
