linux-kernel - Re: [PATCH v10 1/4] drm/panthor: Rework panthor_irq::suspended into panthor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260116142132.6e0ee6b8@fedora>
Date: Fri, 16 Jan 2026 14:21:32 +0100
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Cc: Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Chia-I Wu
 <olvaffe@...il.com>, Karunika Choo <karunika.choo@....com>,
 kernel@...labora.com, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v10 1/4] drm/panthor: Rework panthor_irq::suspended into
 panthor_irq::state

On Fri, 16 Jan 2026 13:57:30 +0100
Nicolas Frattaroli <nicolas.frattaroli@...labora.com> wrote:

> To deal with the threaded interrupt handler and a suspend action
> overlapping, the boolean panthor_irq::suspended is not sufficient.
> 
> Rework it into taking several different values depending on the current
> state, and check it and set it within the IRQ helper functions.
> 
> Co-developed-by: Boris Brezillon <boris.brezillon@...labora.com>
> Signed-off-by: Boris Brezillon <boris.brezillon@...labora.com>
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>

> ---
>  drivers/gpu/drm/panthor/panthor_device.h | 35 +++++++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index f35e52b9546a..8597b388cc40 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -61,6 +61,17 @@ enum panthor_device_pm_state {
>  	PANTHOR_DEVICE_PM_STATE_SUSPENDING,
>  };
>  
> +enum panthor_irq_state {
> +	/** @PANTHOR_IRQ_STATE_ACTIVE: IRQ is active and ready to process events. */
> +	PANTHOR_IRQ_STATE_ACTIVE = 0,
> +	/** @PANTHOR_IRQ_STATE_PROCESSING: IRQ is currently processing events. */
> +	PANTHOR_IRQ_STATE_PROCESSING,
> +	/** @PANTHOR_IRQ_STATE_SUSPENDED: IRQ is suspended. */
> +	PANTHOR_IRQ_STATE_SUSPENDED,
> +	/** @PANTHOR_IRQ_STATE_SUSPENDING: IRQ is being suspended. */
> +	PANTHOR_IRQ_STATE_SUSPENDING,
> +};
> +
>  /**
>   * struct panthor_irq - IRQ data
>   *
> @@ -76,8 +87,8 @@ struct panthor_irq {
>  	/** @mask: Current mask being applied to xxx_INT_MASK. */
>  	u32 mask;
>  
> -	/** @suspended: Set to true when the IRQ is suspended. */
> -	atomic_t suspended;
> +	/** @state: one of &enum panthor_irq_state reflecting the current state. */
> +	atomic_t state;
>  };
>  
>  /**
> @@ -409,12 +420,17 @@ static irqreturn_t panthor_ ## __name ## _irq_raw_handler(int irq, void *data)
>  {												\
>  	struct panthor_irq *pirq = data;							\
>  	struct panthor_device *ptdev = pirq->ptdev;						\
> +	enum panthor_irq_state old_state;							\
>  												\
> -	if (atomic_read(&pirq->suspended))							\
> -		return IRQ_NONE;								\
>  	if (!gpu_read(ptdev, __reg_prefix ## _INT_STAT))					\
>  		return IRQ_NONE;								\
>  												\
> +	old_state = atomic_cmpxchg(&pirq->state,						\
> +				   PANTHOR_IRQ_STATE_ACTIVE,					\
> +				   PANTHOR_IRQ_STATE_PROCESSING);				\
> +	if (old_state != PANTHOR_IRQ_STATE_ACTIVE)						\
> +		return IRQ_NONE;								\
> +												\
>  	gpu_write(ptdev, __reg_prefix ## _INT_MASK, 0);						\
>  	return IRQ_WAKE_THREAD;									\
>  }												\
> @@ -423,6 +439,7 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
>  {												\
>  	struct panthor_irq *pirq = data;							\
>  	struct panthor_device *ptdev = pirq->ptdev;						\
> +	enum panthor_irq_state old_state;							\
>  	irqreturn_t ret = IRQ_NONE;								\
>  												\
>  	while (true) {										\
> @@ -435,7 +452,10 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
>  		ret = IRQ_HANDLED;								\
>  	}											\
>  												\
> -	if (!atomic_read(&pirq->suspended))							\
> +	old_state = atomic_cmpxchg(&pirq->state,						\
> +				   PANTHOR_IRQ_STATE_PROCESSING,				\
> +				   PANTHOR_IRQ_STATE_ACTIVE);					\
> +	if (old_state == PANTHOR_IRQ_STATE_PROCESSING)						\
>  		gpu_write(ptdev, __reg_prefix ## _INT_MASK, pirq->mask);			\
>  												\
>  	return ret;										\
> @@ -445,14 +465,15 @@ static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)
>  {												\
>  	pirq->mask = 0;										\
>  	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, 0);					\
> +	atomic_set(&pirq->state, PANTHOR_IRQ_STATE_SUSPENDING);					\
>  	synchronize_irq(pirq->irq);								\
> -	atomic_set(&pirq->suspended, true);							\
> +	atomic_set(&pirq->state, PANTHOR_IRQ_STATE_SUSPENDED);					\
>  }												\
>  												\
>  static inline void panthor_ ## __name ## _irq_resume(struct panthor_irq *pirq, u32 mask)	\
>  {												\
> -	atomic_set(&pirq->suspended, false);							\
>  	pirq->mask = mask;									\
> +	atomic_set(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE);					\
>  	gpu_write(pirq->ptdev, __reg_prefix ## _INT_CLEAR, mask);				\
>  	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, mask);				\
>  }												\
>