[PATCH 4/5] staging: vchiq_arm: Create keep-alive thread during probe
Maíra Canal
mcanal at igalia.com
Thu Jun 26 13:30:25 PDT 2025
Hi Stefan,
On 26/06/25 17:14, Stefan Wahren wrote:
> Hi Maíra,
>
> [add Arnd]
>
> Am 26.06.25 um 20:22 schrieb Maíra Canal:
>> Hi Stefan,
>>
>> On 09/03/25 09:50, Stefan Wahren wrote:
>>> Creating the keep-alive thread in vchiq_platform_init_state have
>>> the following advantages:
>>> - abort driver probe if kthread_create fails (more consistent behavior)
>>> - make resource release process easier
>>>
>>> Since vchiq_keepalive_thread_func is defined below
>>> vchiq_platform_init_state, the latter must be moved.
>>>
>>> Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
>>> ---
>>> .../interface/vchiq_arm/vchiq_arm.c | 69 +++++++++----------
>>> 1 file changed, 34 insertions(+), 35 deletions(-)
>>>
>>
>> After this patch landed on 6.12 stable, I started to observe the
>> following warning in Mesa CI [1]:
> Is this also reproducible with 6.15.x or mainline ?
I was able to reproduce it with 6.16.0-rc2 [2].
[2] https://gitlab.freedesktop.org/mairacanal/mesa/-/jobs/79092300
Best Regards,
- Maíra
>>
>> 20:07:07.830: [ 242.653532] INFO: task vchiq-keep/0:85 blocked for
>> more than 120 seconds.
>> 20:07:07.835: [ 242.660404] Not tainted 6.12.34-v8-+ #13
>> 20:07:07.843: [ 242.666173] "echo 0 > /proc/sys/kernel/
>> hung_task_timeout_secs" disables this message.
>> 20:07:07.852: [ 242.677126] task:vchiq-keep/0 state:D stack:0
>> pid:85 tgid:85 ppid:2 flags:0x00000008
>> 20:07:07.854: [ 242.690734] Call trace:
>> 20:07:07.857: [ 242.693191] __switch_to+0x188/0x230
>> 20:07:07.858: [ 242.697010] __schedule+0xa54/0xb28
>> 20:07:07.859: [ 242.704889] schedule+0x80/0x120
>> 20:07:07.859: [ 242.712581] schedule_preempt_disabled+0x30/0x50
>> 20:07:07.860: [ 242.721437] kthread+0xd4/0x1a0
>> 20:07:07.861: [ 242.724606] ret_from_fork+0x10/0x20
>>
>> If I revert this patch, I no longer get those warnings. From that, I was
>> wondering: is it possible that in some scenarios, we might never
>> actually get to the connected state and therefore, we wouldn't wake up
>> the kthread that we created when we initialized the state?
> Sure we communicate to the VideoCore and there might be reasons the
> connection fail. I'm not aware that a missing wakeup cause a hanging task.
>
> Best regards
>>
>> [1] https://gitlab.freedesktop.org/mairacanal/mesa/-/jobs/78940369
>>
>> Best Regards,
>> - Maíra
>>
>>> 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 0c7ea2d0ee85..64f9536f1232 100644
>>> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>>> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
>>> @@ -280,29 +280,6 @@ 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;
>>> @@ -1011,6 +988,39 @@ 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)
>>> @@ -1331,7 +1341,6 @@ 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));
>>> @@ -1346,17 +1355,7 @@ void vchiq_platform_conn_state_changed(struct
>>> vchiq_state *state,
>>>
>>> arm_state->first_connect = 1;
>>> write_unlock_bh(&arm_state->susp_res_lock);
>>> - 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);
>>> - }
>>> + wake_up_process(arm_state->ka_thread);
>>> }
>>>
>>> static const struct of_device_id vchiq_of_match[] = {
>>> --
>>> 2.34.1
>>>
>>>
>>
>>
>
More information about the linux-arm-kernel
mailing list