[PATCH 2/3] Revert "staging: vchiq_arm: Create keep-alive thread during probe"

[Maíra Canal]

Hi Stefan,

On 11/07/25 12:40, Stefan Wahren wrote:
> The commit 86bc88217006 ("staging: vchiq_arm: Create keep-alive thread
> during probe") introduced a regression for certain configurations,
> which doesn't have a VCHIQ user. This results in a unused and hanging
> keep-alive thread:
> 
>    INFO: task vchiq-keep/0:85 blocked for more than 120 seconds.
>          Not tainted 6.12.34-v8-+ #13
>    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>    task:vchiq-keep/0    state:D stack:0 pid:85    tgid:85    ppid:2
>    Call trace:
>     __switch_to+0x188/0x230
>     __schedule+0xa54/0xb28
>     schedule+0x80/0x120
>     schedule_preempt_disabled+0x30/0x50
>     kthread+0xd4/0x1a0
>     ret_from_fork+0x10/0x20
> 
> Fixes: 86bc88217006 ("staging: vchiq_arm: Create keep-alive thread during probe")
> Reported-by: Maíra Canal <maira.canal at usp.br>

If possible, could you use my Igalia e-mail instead (mcanal at igalia.com)?
I mistakenly sent the e-mail reporting using my university e-mail.

> Closes: https://lore.kernel.org/linux-staging/ba35b960-a981-4671-9f7f-060da10feaa1@usp.br/
> Cc: <stable at kernel.org>
> Signed-off-by: Stefan Wahren <wahrenst at gmx.net>

Reviewed-by: Maíra Canal <mcanal at igalia.com>

Best Regards,
- Maíra

> ---
>   .../interface/vchiq_arm/vchiq_arm.c           | 69 ++++++++++---------
>   1 file changed, 35 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> index cdf5687ad4f0..6434cbdc1a6e 100644
> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> @@ -280,6 +280,29 @@ static int vchiq_platform_init(struct platform_device *pdev, struct vchiq_state
>   	return 0;
>   }
>   
> +int
> +vchiq_platform_init_state(struct vchiq_state *state)
> +{
> +	struct vchiq_arm_state *platform_state;
> +
> +	platform_state = devm_kzalloc(state->dev, sizeof(*platform_state), GFP_KERNEL);
> +	if (!platform_state)
> +		return -ENOMEM;
> +
> +	rwlock_init(&platform_state->susp_res_lock);
> +
> +	init_completion(&platform_state->ka_evt);
> +	atomic_set(&platform_state->ka_use_count, 0);
> +	atomic_set(&platform_state->ka_use_ack_count, 0);
> +	atomic_set(&platform_state->ka_release_count, 0);
> +
> +	platform_state->state = state;
> +
> +	state->platform_state = (struct opaque_platform_state *)platform_state;
> +
> +	return 0;
> +}
> +
>   static struct vchiq_arm_state *vchiq_platform_get_arm_state(struct vchiq_state *state)
>   {
>   	return (struct vchiq_arm_state *)state->platform_state;
> @@ -988,39 +1011,6 @@ vchiq_keepalive_thread_func(void *v)
>   	return 0;
>   }
>   
> -int
> -vchiq_platform_init_state(struct vchiq_state *state)
> -{
> -	struct vchiq_arm_state *platform_state;
> -	char threadname[16];
> -
> -	platform_state = devm_kzalloc(state->dev, sizeof(*platform_state), GFP_KERNEL);
> -	if (!platform_state)
> -		return -ENOMEM;
> -
> -	snprintf(threadname, sizeof(threadname), "vchiq-keep/%d",
> -		 state->id);
> -	platform_state->ka_thread = kthread_create(&vchiq_keepalive_thread_func,
> -						   (void *)state, threadname);
> -	if (IS_ERR(platform_state->ka_thread)) {
> -		dev_err(state->dev, "couldn't create thread %s\n", threadname);
> -		return PTR_ERR(platform_state->ka_thread);
> -	}
> -
> -	rwlock_init(&platform_state->susp_res_lock);
> -
> -	init_completion(&platform_state->ka_evt);
> -	atomic_set(&platform_state->ka_use_count, 0);
> -	atomic_set(&platform_state->ka_use_ack_count, 0);
> -	atomic_set(&platform_state->ka_release_count, 0);
> -
> -	platform_state->state = state;
> -
> -	state->platform_state = (struct opaque_platform_state *)platform_state;
> -
> -	return 0;
> -}
> -
>   int
>   vchiq_use_internal(struct vchiq_state *state, struct vchiq_service *service,
>   		   enum USE_TYPE_E use_type)
> @@ -1341,6 +1331,7 @@ void vchiq_platform_conn_state_changed(struct vchiq_state *state,
>   				       enum vchiq_connstate newstate)
>   {
>   	struct vchiq_arm_state *arm_state = vchiq_platform_get_arm_state(state);
> +	char threadname[16];
>   
>   	dev_dbg(state->dev, "suspend: %d: %s->%s\n",
>   		state->id, get_conn_state_name(oldstate), get_conn_state_name(newstate));
> @@ -1355,7 +1346,17 @@ void vchiq_platform_conn_state_changed(struct vchiq_state *state,
>   
>   	arm_state->first_connect = 1;
>   	write_unlock_bh(&arm_state->susp_res_lock);
> -	wake_up_process(arm_state->ka_thread);
> +	snprintf(threadname, sizeof(threadname), "vchiq-keep/%d",
> +		 state->id);
> +	arm_state->ka_thread = kthread_create(&vchiq_keepalive_thread_func,
> +					      (void *)state,
> +					      threadname);
> +	if (IS_ERR(arm_state->ka_thread)) {
> +		dev_err(state->dev, "suspend: Couldn't create thread %s\n",
> +			threadname);
> +	} else {
> +		wake_up_process(arm_state->ka_thread);
> +	}
>   }
>   
>   static const struct of_device_id vchiq_of_match[] = {