linux-kernel - Re: [PATCH 1/1] coresight: prevent deactivate active config while enable the config

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Message-ID: <Z2qJMGPD8x2npFaX@e129823.arm.com>
Date: Tue, 24 Dec 2024 10:13:04 +0000
From: Yeoreum Yun <yeoreum.yun@....com>
To: James Clark <james.clark@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>, coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	nd@....com, suzuki.poulose@....com,
	alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH 1/1] coresight: prevent deactivate active config while
 enable the config

Hi James.
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> > index a70c1454b410..dfa7dcbaf25d 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> > @@ -953,7 +953,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti
> >   			cscfg_mgr->sysfs_active_config = cfg_hash;
> >   	} else {
> >   		/* disable if matching current value */
> > -		if (cscfg_mgr->sysfs_active_config == cfg_hash) {
> > +		if (cscfg_mgr->sysfs_active_config == cfg_hash &&
> > +		    !atomic_read(&cscfg_mgr->sys_enable_cnt)) {
> >   			_cscfg_deactivate_config(cfg_hash);
>
> So is sys_enable_cnt a global value? If a fix is needed doesn't it need to
> be a per-config refcount?
>
> Say you have two active configs, sys_enable_cnt is now 2, how do you disable
> one without it always skipping here when the other config is enabled?

Sorry to miss this one!.
Because when one configuration is enabled,
cscfg_mgr->sysfs_active_config becomes !NULL, so it wouldn't happen
there is no two activate configurations. so sys_enable_cnt wouldn't be
2.