[PATCH 2.6] sysfs_remove_dir

[PATCH 2.6] sysfs_remove_dir

[Maneesh Soni]

Hi Pat,

sysfs_remove_dir() does not remove the contents of subdirs corresponding
to the attribute groups of a kobject. The following patch fixes this by first
removing the subdir contents and then removing thus emptied subdirs along
with the other attribute files of the kobject and plugs the memory
leakage resulting from orphan dentries.

I tested it by inserting and removing "dummy.o" network module and verifying
that dentires corresponding to "statistics" attribute group are removed.

Please comment.

Thanks
Maneesh



 o sysfs_remove_dir() has to remove the files in the subdirs (corresponding
   to the attribute groups) and then remove such empty subdirs along with the 
   other attribute files for the given kobject. The following patch does this
   assuming that there are/will be no attribute sub-groups.


 fs/sysfs/dir.c |   22 +++++++++++++++++-----
 1 files changed, 17 insertions(+), 5 deletions(-)

diff -puN fs/sysfs/dir.c~sysfs_remove_dir-fix fs/sysfs/dir.c
--- linux-2.6.0-test5-mm2/fs/sysfs/dir.c~sysfs_remove_dir-fix	2003-09-15 15:08:45.000000000 +0530
+++ linux-2.6.0-test5-mm2-maneesh/fs/sysfs/dir.c	2003-09-15 15:26:04.000000000 +0530
@@ -119,23 +119,30 @@ void sysfs_remove_dir(struct kobject * k
 {
 	struct list_head * node;
 	struct dentry * dentry = dget(kobj->dentry);
+	struct dentry * parent;
 
 	if (!dentry)
 		return;
 
 	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
-	down(&dentry->d_inode->i_sem);
 
+	parent = dentry;
+	down(&parent->d_inode->i_sem);
 	spin_lock(&dcache_lock);
-	node = dentry->d_subdirs.next;
-	while (node != &dentry->d_subdirs) {
-		struct dentry * d = list_entry(node,struct dentry,d_child);
+repeat:
+	node = parent->d_subdirs.next;
+	while (node != &parent->d_subdirs) {
+		struct dentry * d = list_entry(node, struct dentry, d_child);
 		list_del_init(node);
 
 		pr_debug(" o %s (%d): ",d->d_name.name,atomic_read(&d->d_count));
 		if (d->d_inode) {
 			d = dget_locked(d);
 			pr_debug("removing");
+			if (!list_empty(&d->d_subdirs)) {
+				parent = d;
+				goto repeat;
+			}
 
 			/**
 			 * Unlink and unhash.
@@ -147,7 +154,12 @@ void sysfs_remove_dir(struct kobject * k
 			spin_lock(&dcache_lock);
 		}
 		pr_debug(" done\n");
-		node = dentry->d_subdirs.next;
+		node = parent->d_subdirs.next;
+	}
+
+	if (!list_empty(&dentry->d_subdirs)) {
+		parent = dentry;
+		goto repeat;
 	}
 	list_del_init(&dentry->d_child);
 	spin_unlock(&dcache_lock);

_

-- 
Maneesh Soni
Linux Technology Center, 
IBM Software Lab, Bangalore, India
email: maneesh@in.ibm.com
Phone: 91-80-5044999 Fax: 91-80-5268553
T/L : 9243696

Re: [PATCH 2.6] sysfs_remove_dir

[Hanna Linder]

Maneesh, Pat,

Just wanted to let you know I ran this patch
on 2.6.0-test5 with my input class patch and there
were no problems. Still working on my patch though.

Hanna


--On Monday, September 15, 2003 03:51:28 PM +0530 Maneesh Soni <maneesh@in.ibm.com> wrote:

> 
> Hi Pat,
> 
> sysfs_remove_dir() does not remove the contents of subdirs corresponding
> to the attribute groups of a kobject. The following patch fixes this by first
> removing the subdir contents and then removing thus emptied subdirs along
> with the other attribute files of the kobject and plugs the memory
> leakage resulting from orphan dentries.
> 
> I tested it by inserting and removing "dummy.o" network module and verifying
> that dentires corresponding to "statistics" attribute group are removed.
> 
> Please comment.
> 
> Thanks
> Maneesh
> 
> 
> 
>  o sysfs_remove_dir() has to remove the files in the subdirs (corresponding
>    to the attribute groups) and then remove such empty subdirs along with the 
>    other attribute files for the given kobject. The following patch does this
>    assuming that there are/will be no attribute sub-groups.
> 
> 
>  fs/sysfs/dir.c |   22 +++++++++++++++++-----
>  1 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff -puN fs/sysfs/dir.c~sysfs_remove_dir-fix fs/sysfs/dir.c
> --- linux-2.6.0-test5-mm2/fs/sysfs/dir.c~sysfs_remove_dir-fix	2003-09-15 15:08:45.000000000 +0530
> +++ linux-2.6.0-test5-mm2-maneesh/fs/sysfs/dir.c	2003-09-15 15:26:04.000000000 +0530
> @@ -119,23 +119,30 @@ void sysfs_remove_dir(struct kobject * k
>  {
>  	struct list_head * node;
>  	struct dentry * dentry = dget(kobj->dentry);
> +	struct dentry * parent;
>  
>  	if (!dentry)
>  		return;
>  
>  	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
> -	down(&dentry->d_inode->i_sem);
>  
> +	parent = dentry;
> +	down(&parent->d_inode->i_sem);
>  	spin_lock(&dcache_lock);
> -	node = dentry->d_subdirs.next;
> -	while (node != &dentry->d_subdirs) {
> -		struct dentry * d = list_entry(node,struct dentry,d_child);
> +repeat:
> +	node = parent->d_subdirs.next;
> +	while (node != &parent->d_subdirs) {
> +		struct dentry * d = list_entry(node, struct dentry, d_child);
>  		list_del_init(node);
>  
>  		pr_debug(" o %s (%d): ",d->d_name.name,atomic_read(&d->d_count));
>  		if (d->d_inode) {
>  			d = dget_locked(d);
>  			pr_debug("removing");
> +			if (!list_empty(&d->d_subdirs)) {
> +				parent = d;
> +				goto repeat;
> +			}
>  
>  			/**
>  			 * Unlink and unhash.
> @@ -147,7 +154,12 @@ void sysfs_remove_dir(struct kobject * k
>  			spin_lock(&dcache_lock);
>  		}
>  		pr_debug(" done\n");
> -		node = dentry->d_subdirs.next;
> +		node = parent->d_subdirs.next;
> +	}
> +
> +	if (!list_empty(&dentry->d_subdirs)) {
> +		parent = dentry;
> +		goto repeat;
>  	}
>  	list_del_init(&dentry->d_child);
>  	spin_unlock(&dcache_lock);
> 
> _
> 
> -- 
> Maneesh Soni
> Linux Technology Center, 
> IBM Software Lab, Bangalore, India
> email: maneesh@in.ibm.com
> Phone: 91-80-5044999 Fax: 91-80-5268553
> T/L : 9243696
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 
> 

Re: [PATCH 2.6] sysfs_remove_dir

[Patrick Mochel]

> sysfs_remove_dir() does not remove the contents of subdirs corresponding
> to the attribute groups of a kobject. The following patch fixes this by first
> removing the subdir contents and then removing thus emptied subdirs along
> with the other attribute files of the kobject and plugs the memory
> leakage resulting from orphan dentries.
> 
> I tested it by inserting and removing "dummy.o" network module and verifying
> that dentires corresponding to "statistics" attribute group are removed.

Sorry it's taken a while to reply, but I even now haven't had a chance to 
look that deep into this problem. I will say that this is the wrong 
approach to the problem. 

Upon initial inspection, it looks like it will do the right thing in all 
cases, except when a parent is removed before a child is (but we don't 
technically support that now). 

However, I'd like to move away from the automatic cleanup that sysfs was 
doing. attribute groups make it easier to clean up all the files that are 
created for an object when the object is removed. I would like to see that 
removal call inserted where necessary, instead of adding this complication 
to the sysfs core.

I intend to remove the automatic cleanup in sysfs_remove_dir(), but 
haven't gotten around to it.. 

Thanks,



	Pat

Re: [PATCH 2.6] sysfs_remove_dir

[Maneesh Soni]

On Fri, Sep 19, 2003 at 04:02:15PM -0700, Patrick Mochel wrote:
> 
> > sysfs_remove_dir() does not remove the contents of subdirs corresponding
> > to the attribute groups of a kobject. The following patch fixes this by first
> > removing the subdir contents and then removing thus emptied subdirs along
> > with the other attribute files of the kobject and plugs the memory
> > leakage resulting from orphan dentries.
> > 
> > I tested it by inserting and removing "dummy.o" network module and verifying
> > that dentires corresponding to "statistics" attribute group are removed.
> 
> Sorry it's taken a while to reply, but I even now haven't had a chance to 
> look that deep into this problem. I will say that this is the wrong 
> approach to the problem. 
> 
> Upon initial inspection, it looks like it will do the right thing in all 
> cases, except when a parent is removed before a child is (but we don't 
> technically support that now). 
> 
> However, I'd like to move away from the automatic cleanup that sysfs was 
> doing. attribute groups make it easier to clean up all the files that are 
> created for an object when the object is removed. I would like to see that 
> removal call inserted where necessary, instead of adding this complication 
> to the sysfs core.
> 
> I intend to remove the automatic cleanup in sysfs_remove_dir(), but 
> haven't gotten around to it.. 
> 

ok.. my intention was not to change callers for removing attribute group and 
keep the changes within sysfs. But if you prefer otherway (I too :-)), please 
see the patch below. As of now I can see only netdev not releasing attribute 
group. I guess power subsystem don't need to remove attribute groups created 
in pm_init() and pm_disk_init() as these don't unregister from sysfs.

Thanks
Maneesh

o attribute group should be removed while unregistering from sysfs. netdev
  does not do this and leaks dentries belonging to the attribute group. 
  The following patch removes the attribute group when netdev is unregistered.


 net/core/dev.c       |    3 ++-
 net/core/net-sysfs.c |   25 +++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 3 deletions(-)

diff -puN net/core/net-sysfs.c~sysfs-dentry-leak-fix net/core/net-sysfs.c
--- linux-2.6.0-test5-mm3/net/core/net-sysfs.c~sysfs-dentry-leak-fix	2003-09-22 09:45:04.000000000 +0530
+++ linux-2.6.0-test5-mm3-maneesh/net/core/net-sysfs.c	2003-09-22 09:45:17.000000000 +0530
@@ -383,6 +383,21 @@ static struct class net_class = {
 #endif
 };
 
+void netdev_unregister_sysfs(struct net_device * net)
+{
+	struct class_device * class_dev = &(net->class_dev);
+
+	if (net->get_stats)
+		sysfs_remove_group(&class_dev->kobj, &netstat_group);
+
+#ifdef WIRELESS_EXT
+	if (net->get_wireless_stats)
+		sysfs_remove_group(&class_dev->kobj, &wireless_group);
+#endif
+	class_device_del(class_dev);
+
+}
+
 /* Create sysfs entries for network device. */
 int netdev_register_sysfs(struct net_device *net)
 {
@@ -411,9 +426,15 @@ int netdev_register_sysfs(struct net_dev
 #ifdef WIRELESS_EXT
 	if (net->get_wireless_stats &&
 	    (ret = sysfs_create_group(&class_dev->kobj, &wireless_group)))
-		goto out_unreg; 
-#endif
+		goto out_cleanup; 
+
+	return 0;
+out_cleanup:
+	if (net->get_stats)
+		sysfs_remove_group(&class_dev->kobj, &netstat_group);
+#else
 	return 0;
+#endif
 
 out_unreg:
 	printk(KERN_WARNING "%s: sysfs attribute registration failed %d\n",
diff -puN net/core/dev.c~sysfs-dentry-leak-fix net/core/dev.c
--- linux-2.6.0-test5-mm3/net/core/dev.c~sysfs-dentry-leak-fix	2003-09-22 09:45:08.000000000 +0530
+++ linux-2.6.0-test5-mm3-maneesh/net/core/dev.c	2003-09-22 09:45:17.000000000 +0530
@@ -183,6 +183,7 @@ int netdev_fastroute_obstacles;
 
 extern int netdev_sysfs_init(void);
 extern int netdev_register_sysfs(struct net_device *);
+extern int netdev_unregister_sysfs(struct net_device *);
 #ifdef CONFIG_KGDB
 extern int kgdb_net_interrupt(struct sk_buff *skb);
 #endif
@@ -2834,7 +2835,7 @@ void netdev_run_todo(void)
 			break;
 
 		case NETREG_UNREGISTERING:
-			class_device_del(&dev->class_dev);
+			netdev_unregister_sysfs(dev);
 			dev->reg_state = NETREG_UNREGISTERED;
 
 			netdev_wait_allrefs(dev);

_

Re: [PATCH 2.6] sysfs_remove_dir

[Maneesh Soni]

Thanks Stephen for letting me know.

Maneesh

Rediffed for 2.6.0-test5.

o attribute group should be removed while unregistering from sysfs. netdev
  does not do this and leaks dentries belonging to the attribute group. 
  The following patch removes the attribute group when netdev is unregistered.


 net/core/dev.c       |    3 ++-
 net/core/net-sysfs.c |   25 +++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 3 deletions(-)

diff -puN net/core/net-sysfs.c~sysfs-dentry-leak-fix net/core/net-sysfs.c
--- linux-2.6.0-test5/net/core/net-sysfs.c~sysfs-dentry-leak-fix	2003-09-23 09:32:01.000000000 +0530
+++ linux-2.6.0-test5-maneesh/net/core/net-sysfs.c	2003-09-23 09:32:23.000000000 +0530
@@ -383,6 +383,21 @@ static struct class net_class = {
 #endif
 };
 
+void netdev_unregister_sysfs(struct net_device * net)
+{
+	struct class_device * class_dev = &(net->class_dev);
+
+	if (net->get_stats)
+		sysfs_remove_group(&class_dev->kobj, &netstat_group);
+
+#ifdef WIRELESS_EXT
+	if (net->get_wireless_stats)
+		sysfs_remove_group(&class_dev->kobj, &wireless_group);
+#endif
+	class_device_del(class_dev);
+
+}
+
 /* Create sysfs entries for network device. */
 int netdev_register_sysfs(struct net_device *net)
 {
@@ -411,9 +426,15 @@ int netdev_register_sysfs(struct net_dev
 #ifdef WIRELESS_EXT
 	if (net->get_wireless_stats &&
 	    (ret = sysfs_create_group(&class_dev->kobj, &wireless_group)))
-		goto out_unreg; 
-#endif
+		goto out_cleanup; 
+
+	return 0;
+out_cleanup:
+	if (net->get_stats)
+		sysfs_remove_group(&class_dev->kobj, &netstat_group);
+#else
 	return 0;
+#endif
 
 out_unreg:
 	printk(KERN_WARNING "%s: sysfs attribute registration failed %d\n",
diff -puN net/core/dev.c~sysfs-dentry-leak-fix net/core/dev.c
--- linux-2.6.0-test5/net/core/dev.c~sysfs-dentry-leak-fix	2003-09-23 09:31:21.000000000 +0530
+++ linux-2.6.0-test5-maneesh/net/core/dev.c	2003-09-23 09:33:04.000000000 +0530
@@ -183,6 +183,7 @@ int netdev_fastroute_obstacles;
 
 extern int netdev_sysfs_init(void);
 extern int netdev_register_sysfs(struct net_device *);
+extern int netdev_unregister_sysfs(struct net_device *);
 
 
 /*******************************************************************************
@@ -2819,7 +2820,7 @@ void netdev_run_todo(void)
 			break;
 
 		case NETREG_UNREGISTERING:
-			class_device_del(&dev->class_dev);
+			netdev_unregister_sysfs(dev);
 			dev->reg_state = NETREG_UNREGISTERED;
 
 			netdev_wait_allrefs(dev);

_
-- 
Maneesh Soni
Linux Technology Center, 
IBM Software Lab, Bangalore, India
email: maneesh@in.ibm.com
Phone: 91-80-5044999 Fax: 91-80-5268553
T/L : 9243696