linux-kernel - Re: [V3 7/7] remoteproc: sysmon: Send sysmon state only for running rprocs

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Date:   Wed, 6 Jul 2022 14:43:43 +0200
From:   Konrad Dybcio <konrad.dybcio@...ainline.org>
To:     Sibi Sankar <quic_sibis@...cinc.com>, bjorn.andersson@...aro.org
Cc:     agross@...nel.org, mathieu.poirier@...aro.org,
        dmitry.baryshkov@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Siddharth Gupta <sidgup@...eaurora.org>
Subject: Re: [V3 7/7] remoteproc: sysmon: Send sysmon state only for running
 rprocs



On 5.07.2022 14:08, Sibi Sankar wrote:
> From: Siddharth Gupta <sidgup@...eaurora.org>
> 
> When a new remoteproc boots up, send the sysmon state notification
> of only running remoteprocs. Sending state of remoteprocs booting
> up in parallel can cause a race between SSR clients of the remoteproc
> that is booting up and the sysmon notification for the same remoteproc,
> resulting in an inconsistency between which state the remoteproc that
> is booting up in parallel.
> 
> For example - if remoteproc A and B crash one after the other, after
> remoteproc A boots up, if the remoteproc A tries to get the state of
> remoteproc B before the sysmon subdevice for B is invoked but after
> the ssr subdevice of B has been invoked, clients on remoteproc A
> might get confused when the sysmon notification indicates a different
> state.
> 
> Signed-off-by: Siddharth Gupta <sidgup@...eaurora.org>
> Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@...ainline.org>

Konrad
>  drivers/remoteproc/qcom_sysmon.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/qcom_sysmon.c b/drivers/remoteproc/qcom_sysmon.c
> index a9f04dd83ab6..57dde2a69b9d 100644
> --- a/drivers/remoteproc/qcom_sysmon.c
> +++ b/drivers/remoteproc/qcom_sysmon.c
> @@ -512,10 +512,12 @@ static int sysmon_start(struct rproc_subdev *subdev)
>  
>  	mutex_lock(&sysmon_lock);
>  	list_for_each_entry(target, &sysmon_list, node) {
> -		if (target == sysmon)
> +		mutex_lock(&target->state_lock);
> +		if (target == sysmon || target->state != SSCTL_SSR_EVENT_AFTER_POWERUP) {
> +			mutex_unlock(&target->state_lock);
>  			continue;
> +		}
>  
> -		mutex_lock(&target->state_lock);
>  		event.subsys_name = target->name;
>  		event.ssr_event = target->state;
>