linux-kernel - Re: [PATCH] coresight: cti: Fix error handling in probe

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Date:   Fri, 12 Jun 2020 20:42:16 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Mike Leach <mike.leach@...aro.org>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] coresight: cti: Fix error handling in probe

On Fri, Jun 12, 2020 at 03:11:33PM +0300, Dan Carpenter wrote:
> +static int cti_pm_setup(struct cti_drvdata *drvdata)
> +{
> +	int ret;
> +
> +	if (drvdata->ctidev.cpu == -1)
> +		return 0;
> +
> +	if (nr_cti_cpu)
> +		goto done;
> +
> +	cpus_read_lock();
        ^^^^^^^^^^^^^^^^
One thing which I do wonder is why we have locking here but not in the
cti_pm_release() function.  That was how the original code was so the
patch doesn't change anything, but I am curious.

> +	ret = cpuhp_setup_state_nocalls_cpuslocked(
> +			CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
> +			"arm/coresight_cti:starting",
> +			cti_starting_cpu, cti_dying_cpu);
> +	if (ret) {
> +		cpus_read_unlock();
> +		return ret;
> +	}
> +
> +	ret = cpu_pm_register_notifier(&cti_cpu_pm_nb);
> +	cpus_read_unlock();
> +	if (ret) {
> +		cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
> +		return ret;
> +	}
> +
> +done:
> +	nr_cti_cpu++;
> +	cti_cpu_drvdata[drvdata->ctidev.cpu] = drvdata;
> +
> +	return 0;
> +}
> +
>  /* release PM registrations */
>  static void cti_pm_release(struct cti_drvdata *drvdata)
>  {
> -	if (drvdata->ctidev.cpu >= 0) {
> -		if (--nr_cti_cpu == 0) {
> -			cpu_pm_unregister_notifier(&cti_cpu_pm_nb);
> +	if (drvdata->ctidev.cpu == -1)
> +		return;
>  
> -			cpuhp_remove_state_nocalls(
> -				CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
> -		}
> -		cti_cpu_drvdata[drvdata->ctidev.cpu] = NULL;
> +	cti_cpu_drvdata[drvdata->ctidev.cpu] = drvdata;
> +	if (--nr_cti_cpu == 0) {
> +		cpu_pm_unregister_notifier(&cti_cpu_pm_nb);
> +		cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
>  	}
>  }

regards,
dan carpenter