Re: [PATCH v2 1/6] drm/rockchip: Convert psr_list_mutex to spinlock and use it

From: Yakir Yang <ykk@rock-chips.com>
To: Sean Paul <seanpaul@chromium.org>,
	mark.yao@rock-chips.com, dri-devel@lists.freedesktop.org
Cc: marcheu@chromium.org, dianders@chromium.org,
	linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v2 1/6] drm/rockchip: Convert psr_list_mutex to spinlock and use it
Date: Wed, 17 Aug 2016 10:29:59 +0800	[thread overview]
Message-ID: <37178adb-5cf4-f5e3-d1d5-fe2a312c49ad@rock-chips.com> (raw)
In-Reply-To: <1471396276-8222-2-git-send-email-seanpaul@chromium.org>


On 08/17/2016 09:11 AM, Sean Paul wrote:
> This patch converts the psr_list_mutex to a spinlock and locks
> all access to psr_list to avoid races (however unlikely they
> were).
>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Yakir Yang <ykk@rock-chips.com>
> ---
>
> Changes in v2:
> 	- Rebased on https://cgit.freedesktop.org/~seanpaul/dogwood/log/?h=for-next
>
>   drivers/gpu/drm/rockchip/rockchip_drm_drv.c |  2 +-
>   drivers/gpu/drm/rockchip/rockchip_drm_drv.h |  2 +-
>   drivers/gpu/drm/rockchip/rockchip_drm_psr.c | 25 ++++++++++++++++++-------
>   3 files changed, 20 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> index b43fe5d9..76eaf1d 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
> @@ -157,7 +157,7 @@ static int rockchip_drm_bind(struct device *dev)
>   	drm_dev->dev_private = private;
>   
>   	INIT_LIST_HEAD(&private->psr_list);
> -	mutex_init(&private->psr_list_mutex);
> +	spin_lock_init(&private->psr_list_lock);
>   
>   	drm_mode_config_init(drm_dev);
>   
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> index 9c34c9e..5c69845 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> @@ -63,7 +63,7 @@ struct rockchip_drm_private {
>   	struct drm_atomic_state *state;
>   
>   	struct list_head psr_list;
> -	struct mutex psr_list_mutex;
> +	spinlock_t psr_list_lock;
>   };
>   
>   int rockchip_register_crtc_funcs(struct drm_crtc *crtc,
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> index a6d3bd25..bd25273 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
> @@ -45,12 +45,18 @@ static struct psr_drv *find_psr_by_crtc(struct drm_crtc *crtc)
>   {
>   	struct rockchip_drm_private *drm_drv = crtc->dev->dev_private;
>   	struct psr_drv *psr;
> +	unsigned long flags;
>   
> -	list_for_each_entry(psr, &drm_drv->psr_list, list)
> +	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
> +	list_for_each_entry(psr, &drm_drv->psr_list, list) {
>   		if (psr->encoder->crtc == crtc)
> -			return psr;
> +			goto out;
> +	}
> +	psr = ERR_PTR(-ENODEV);
>   
> -	return ERR_PTR(-ENODEV);
> +out:
> +	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
> +	return psr;
>   }
>   
>   static void psr_state_work(struct work_struct *work)
> @@ -173,7 +179,9 @@ void rockchip_drm_psr_flush(struct drm_device *dev)
>   {
>   	struct rockchip_drm_private *drm_drv = dev->dev_private;
>   	struct psr_drv *psr;
> +	unsigned long flags;
>   
> +	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
>   	list_for_each_entry(psr, &drm_drv->psr_list, list) {
>   		if (psr->request_state == PSR_DISABLE)
>   			continue;
> @@ -183,6 +191,7 @@ void rockchip_drm_psr_flush(struct drm_device *dev)
>   
>   		psr_set_state(psr, PSR_FLUSH);
>   	}
> +	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
>   }
>   EXPORT_SYMBOL(rockchip_drm_psr_flush);
>   
> @@ -199,6 +208,7 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
>   {
>   	struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
>   	struct psr_drv *psr;
> +	unsigned long flags;
>   
>   	if (!encoder || !psr_set)
>   		return -EINVAL;
> @@ -215,9 +225,9 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
>   	psr->encoder = encoder;
>   	psr->set = psr_set;
>   
> -	mutex_lock(&drm_drv->psr_list_mutex);
> +	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
>   	list_add_tail(&psr->list, &drm_drv->psr_list);
> -	mutex_unlock(&drm_drv->psr_list_mutex);
> +	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
>   
>   	return 0;
>   }
> @@ -235,8 +245,9 @@ void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
>   {
>   	struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
>   	struct psr_drv *psr, *n;
> +	unsigned long flags;
>   
> -	mutex_lock(&drm_drv->psr_list_mutex);
> +	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
>   	list_for_each_entry_safe(psr, n, &drm_drv->psr_list, list) {
>   		if (psr->encoder == encoder) {
>   			del_timer(&psr->flush_timer);
> @@ -244,6 +255,6 @@ void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
>   			kfree(psr);
>   		}
>   	}
> -	mutex_unlock(&drm_drv->psr_list_mutex);
> +	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
>   }
>   EXPORT_SYMBOL(rockchip_drm_psr_unregister);


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