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Message-ID: <eec66692543e7dee94b3af111b87c9935d11ee6f.camel@bootlin.com>
Date: Fri, 22 Mar 2019 11:48:03 +0100
From: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To: Eric Anholt <eric@...olt.net>, dri-devel@...ts.freedesktop.org
Cc: linux-kernel@...r.kernel.org,
Maxime Ripard <maxime.ripard@...tlin.com>
Subject: Re: [PATCH 6/7] drm/vc4: Add helpers for pm get/put.
Hi,
Le mercredi 20 février 2019 à 13:03 -0800, Eric Anholt a écrit :
> This makes sure the vc4_reset doesn't hit an obscure race with the
> GET_PARAM ioctl, fixes a decrement outside of the lock, and prevents
> future code from making mistakes with the weird return value of
> pm_runtime_get_sync().
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cheers,
Paul
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
> drivers/gpu/drm/vc4/vc4_drv.c | 21 +++++++++------------
> drivers/gpu/drm/vc4/vc4_drv.h | 2 ++
> drivers/gpu/drm/vc4/vc4_gem.c | 21 +++++----------------
> drivers/gpu/drm/vc4/vc4_v3d.c | 33 +++++++++++++++++++++++++++++++++
> 4 files changed, 49 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
> index de1d0ce11831..f95891a61d52 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.c
> +++ b/drivers/gpu/drm/vc4/vc4_drv.c
> @@ -77,28 +77,25 @@ static int vc4_get_param_ioctl(struct drm_device *dev, void *data,
>
> switch (args->param) {
> case DRM_VC4_PARAM_V3D_IDENT0:
> - ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
> - if (ret < 0)
> + ret = vc4_v3d_pm_get(vc4);
> + if (ret)
> return ret;
> args->value = V3D_READ(V3D_IDENT0);
> - pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
> - pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
> + vc4_v3d_pm_put(vc4);
> break;
> case DRM_VC4_PARAM_V3D_IDENT1:
> - ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
> - if (ret < 0)
> + ret = vc4_v3d_pm_get(vc4);
> + if (ret)
> return ret;
> args->value = V3D_READ(V3D_IDENT1);
> - pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
> - pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
> + vc4_v3d_pm_put(vc4);
> break;
> case DRM_VC4_PARAM_V3D_IDENT2:
> - ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
> - if (ret < 0)
> + ret = vc4_v3d_pm_get(vc4);
> + if (ret)
> return ret;
> args->value = V3D_READ(V3D_IDENT2);
> - pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
> - pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
> + vc4_v3d_pm_put(vc4);
> break;
> case DRM_VC4_PARAM_SUPPORTS_BRANCHES:
> case DRM_VC4_PARAM_SUPPORTS_ETC1:
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index 495c5a13a948..c71988b270bc 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -809,6 +809,8 @@ void vc4_plane_async_set_fb(struct drm_plane *plane,
> /* vc4_v3d.c */
> extern struct platform_driver vc4_v3d_driver;
> int vc4_v3d_get_bin_slot(struct vc4_dev *vc4);
> +int vc4_v3d_pm_get(struct vc4_dev *vc4);
> +void vc4_v3d_pm_put(struct vc4_dev *vc4);
>
> /* vc4_validate.c */
> int
> diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
> index 8d816e5ed762..4544a478f106 100644
> --- a/drivers/gpu/drm/vc4/vc4_gem.c
> +++ b/drivers/gpu/drm/vc4/vc4_gem.c
> @@ -969,12 +969,7 @@ vc4_complete_exec(struct drm_device *dev, struct vc4_exec_info *exec)
> /* Release the reference we had on the perf monitor. */
> vc4_perfmon_put(exec->perfmon);
>
> - mutex_lock(&vc4->power_lock);
> - if (--vc4->power_refcount == 0) {
> - pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
> - pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
> - }
> - mutex_unlock(&vc4->power_lock);
> + vc4_v3d_pm_put(vc4);
>
> kfree(exec);
> }
> @@ -1153,17 +1148,11 @@ vc4_submit_cl_ioctl(struct drm_device *dev, void *data,
> return -ENOMEM;
> }
>
> - mutex_lock(&vc4->power_lock);
> - if (vc4->power_refcount++ == 0) {
> - ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
> - if (ret < 0) {
> - mutex_unlock(&vc4->power_lock);
> - vc4->power_refcount--;
> - kfree(exec);
> - return ret;
> - }
> + ret = vc4_v3d_pm_get(vc4);
> + if (ret) {
> + kfree(exec);
> + return ret;
> }
> - mutex_unlock(&vc4->power_lock);
>
> exec->args = args;
> INIT_LIST_HEAD(&exec->unref_list);
> diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
> index f008584eb739..7820b8eaaa98 100644
> --- a/drivers/gpu/drm/vc4/vc4_v3d.c
> +++ b/drivers/gpu/drm/vc4/vc4_v3d.c
> @@ -124,6 +124,39 @@ static int vc4_v3d_debugfs_ident(struct seq_file *m, void *unused)
> return 0;
> }
>
> +/**
> + * Wraps pm_runtime_get_sync() in a refcount, so that we can reliably
> + * get the pm_runtime refcount to 0 in vc4_reset().
> + */
> +int
> +vc4_v3d_pm_get(struct vc4_dev *vc4)
> +{
> + mutex_lock(&vc4->power_lock);
> + if (vc4->power_refcount++ == 0) {
> + int ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
> +
> + if (ret < 0) {
> + vc4->power_refcount--;
> + mutex_unlock(&vc4->power_lock);
> + return ret;
> + }
> + }
> + mutex_unlock(&vc4->power_lock);
> +
> + return 0;
> +}
> +
> +void
> +vc4_v3d_pm_put(struct vc4_dev *vc4)
> +{
> + mutex_lock(&vc4->power_lock);
> + if (--vc4->power_refcount == 0) {
> + pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
> + pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
> + }
> + mutex_unlock(&vc4->power_lock);
> +}
> +
> static void vc4_v3d_init_hw(struct drm_device *dev)
> {
> struct vc4_dev *vc4 = to_vc4_dev(dev);
--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
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