linux-kernel - Re: [PATCH] drm/vc4: Replace lock/unlock pattern to use guard

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Message-ID: <7d1df5ed-7119-4e59-b1e0-e54aa572282b@igalia.com>
Date: Wed, 12 Nov 2025 09:28:30 -0300
From: Maíra Canal <mcanal@...lia.com>
To: Erick Karanja <karanja99erick@...il.com>, mripard@...nel.org,
 dave.stevenson@...pberrypi.com
Cc: kernel-list@...pberrypi.com, maarten.lankhorst@...ux.intel.com,
 tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/vc4: Replace lock/unlock pattern to use guard

Hi Erick,

On 12/11/25 05:02, Erick Karanja wrote:
> Replace manual lock/unlock patterns with guard.
> This simplifies the code.
> 
> Generated-by: Coccinelle SmPL
> Signed-off-by: Erick Karanja <karanja99erick@...il.com>
> ---
>   drivers/gpu/drm/vc4/vc4_v3d.c | 45 ++++++++++++++---------------------
>   1 file changed, 18 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
> index bb09df5000bd..8271a6610d6e 100644
> --- a/drivers/gpu/drm/vc4/vc4_v3d.c
> +++ b/drivers/gpu/drm/vc4/vc4_v3d.c
> @@ -130,17 +130,15 @@ vc4_v3d_pm_get(struct vc4_dev *vc4)
>   	if (WARN_ON_ONCE(vc4->gen > VC4_GEN_4))
>   		return -ENODEV;
>   
> -	mutex_lock(&vc4->power_lock);
> +	guard(mutex)(&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;
>   }
> @@ -151,12 +149,11 @@ vc4_v3d_pm_put(struct vc4_dev *vc4)
>   	if (WARN_ON_ONCE(vc4->gen > VC4_GEN_4))
>   		return;
>   
> -	mutex_lock(&vc4->power_lock);
> +	guard(mutex)(&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)
> @@ -173,7 +170,6 @@ static void vc4_v3d_init_hw(struct drm_device *dev)
>   int vc4_v3d_get_bin_slot(struct vc4_dev *vc4)
>   {
>   	struct drm_device *dev = &vc4->base;
> -	unsigned long irqflags;
>   	int slot;
>   	uint64_t seqno = 0;
>   	struct vc4_exec_info *exec;
> @@ -182,23 +178,22 @@ int vc4_v3d_get_bin_slot(struct vc4_dev *vc4)
>   		return -ENODEV;
>   
>   try_again:
> -	spin_lock_irqsave(&vc4->job_lock, irqflags);
> -	slot = ffs(~vc4->bin_alloc_used);
> -	if (slot != 0) {
> -		/* Switch from ffs() bit index to a 0-based index. */
> -		slot--;
> -		vc4->bin_alloc_used |= BIT(slot);
> -		spin_unlock_irqrestore(&vc4->job_lock, irqflags);
> -		return slot;
> -	}
> +	scoped_guard (spinlock_irqsave, &vc4->job_lock) {
> +		slot = ffs(~vc4->bin_alloc_used);
> +		if (slot != 0) {
> +			/* Switch from ffs() bit index to a 0-based index. */
> +			slot--;
> +			vc4->bin_alloc_used |= BIT(slot);
> +			return slot;
> +		}
>   
> -	/* Couldn't find an open slot.  Wait for render to complete
> +		/* Couldn't find an open slot.  Wait for render to complete
>   	 * and try again.
>   	 */

Could you please align the rest of the comment?

Best Regards,
- Maíra