linux-kernel - Re: [PATCH v4 8/9] devcg: refactor dev_exception

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Date:	Wed, 30 Jan 2013 20:47:30 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	aris@...hat.com
Cc:	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	Tejun Heo <tj@...nel.org>,
	Serge Hallyn <serge.hallyn@...onical.com>
Subject: Re: [PATCH v4 8/9] devcg: refactor dev_exception_clean()

Quoting aris@...hat.com (aris@...hat.com):
> This patch is in preparation for hierarchy support.
> 
> This patch doesn't introduce any functional changes.
> 
> Acked-by: Tejun Heo <tj@...nel.org>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Serge Hallyn <serge.hallyn@...onical.com>
> Signed-off-by: Aristeu Rozanski <aris@...hat.com>
> 
> ---
>  security/device_cgroup.c |   34 ++++++++++++++++------------------
>  1 file changed, 16 insertions(+), 18 deletions(-)
> 
> --- github.orig/security/device_cgroup.c	2013-01-29 11:49:16.374681863 -0500
> +++ github/security/device_cgroup.c	2013-01-29 11:49:16.653686016 -0500
> @@ -212,32 +212,33 @@ static int dev_exception_add(struct dev_
>  	return rc;
>  }
>  
> -static void __dev_exception_clean(struct dev_cgroup *dev_cgroup)
> +static void dev_exception_clean(struct list_head *exceptions)
>  {
>  	struct dev_exception_item *ex, *tmp;
>  
> -	list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
> -		list_del_rcu(&ex->list);
> -		kfree_rcu(ex, rcu);
> -	}
> -	list_for_each_entry_safe(ex, tmp, &dev_cgroup->local.exceptions,
> -				 list) {
> +	list_for_each_entry_safe(ex, tmp, exceptions, list) {
>  		list_del_rcu(&ex->list);
>  		kfree_rcu(ex, rcu);
>  	}
>  }
>  
> +static void __dev_exception_clean_all(struct dev_cgroup *dev_cgroup)
> +{
> +	dev_exception_clean(&dev_cgroup->exceptions);
> +	dev_exception_clean(&dev_cgroup->local.exceptions);
> +}
> +
>  /**
> - * dev_exception_clean - frees all entries of the exception list
> + * dev_exception_clean_all - frees all entries of the exception list
>   * @dev_cgroup: dev_cgroup with the exception list to be cleaned
>   *
>   * called under devcgroup_mutex
>   */
> -static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
> +static void dev_exception_clean_all(struct dev_cgroup *dev_cgroup)
>  {
>  	lockdep_assert_held(&devcgroup_mutex);
>  
> -	__dev_exception_clean(dev_cgroup);
> +	__dev_exception_clean_all(dev_cgroup);
>  }
>  
>  /**
> @@ -303,7 +304,7 @@ static void devcgroup_css_free(struct cg
>  	struct dev_cgroup *dev_cgroup;
>  
>  	dev_cgroup = cgroup_to_devcgroup(cgroup);
> -	__dev_exception_clean(dev_cgroup);
> +	__dev_exception_clean_all(dev_cgroup);
>  	kfree(dev_cgroup);
>  }
>  
> @@ -508,25 +509,22 @@ 	memset(&ex, 0, sizeof(ex));
>  		case DEVCG_ALLOW:
>  			if (!may_allow_all(parent))
>  				return -EPERM;
> -			dev_exception_clean(devcgroup);
> +			dev_exception_clean_all(devcgroup);
>  			if (parent)
>  				rc = dev_exceptions_copy(&devcgroup->exceptions,
>  							 &parent->exceptions);
>  			devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
>  			devcgroup->local.behavior = DEVCG_DEFAULT_ALLOW;
> -
> -			if (rc)
> -				return rc;

Was this intentional?

I see that you next add

	rc = propagate_behavior(devcgroup);

right here, but this means you're ignoring failure in the
dev_exceptions_copy() call above.

>  			break;
>  		case DEVCG_DENY:
> -			dev_exception_clean(devcgroup);
> +			dev_exception_clean_all(devcgroup);
>  			devcgroup->behavior = DEVCG_DEFAULT_DENY;
>  			devcgroup->local.behavior = DEVCG_DEFAULT_DENY;
>  			break;
>  		default:
> -			return -EINVAL;
> +			rc = -EINVAL;
>  		}
> -		return 0;
> +		return rc;
>  	case 'b':
>  		ex.type = DEV_BLOCK;
>  		break;
> 
> --
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