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([2804:14d:8084:946d:411e:e43:f1b:c7d3]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23abe3f859dsm3626425ad.172.2025.06.26.11.22.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Jun 2025 11:22:22 -0700 (PDT) Message-ID: Date: Thu, 26 Jun 2025 15:22:17 -0300 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/5] staging: vchiq_arm: Create keep-alive thread during probe To: Stefan Wahren , Florian Fainelli , Greg Kroah-Hartman Cc: Umang Jain , Ojaswin Mujoo , Laurent Pinchart , Kieran Bingham , Dan Carpenter , linux-arm-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, kernel-list@raspberrypi.com, linux-staging@lists.linux.dev References: <20250309125014.37166-1-wahrenst@gmx.net> <20250309125014.37166-5-wahrenst@gmx.net> Content-Language: en-US From: =?UTF-8?Q?Ma=C3=ADra_Canal?= In-Reply-To: <20250309125014.37166-5-wahrenst@gmx.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250626_112225_619064_C1600825 X-CRM114-Status: GOOD ( 21.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 > --- > .../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]: 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? [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 > >