Re: 2.5.64 sysfs bug

Patrick Mochel (mochel@osdl.org)
Fri, 7 Mar 2003 09:49:11 -0600 (CST)


On Fri, 7 Mar 2003, David Howells wrote:

>
> Hi, I seem to be getting tripping a bug somewhere with my filesystem now that
> I'm using it with 2.5.64 (no problems of this nature occurred with
> 2.5.63). The problem occurs during rmmod (I don't need to actually mount
> anything):
>
> [root@host135 root]# insmod /tmp/cachefs.ko
> [root@host135 root]# rmmod -f cachefs
> [root@host135 root]# insmod /tmp/cachefs.ko
> [root@host135 root]# rmmod -f cachefs
> Segmentation fault
> [root@host135 root]#
>
> I see this appearing on the console:

Could you try the attached patch, and let me know if it helps?

Thanks,

-pat

===== fs/sysfs/dir.c 1.2 vs edited =====
--- 1.2/fs/sysfs/dir.c Thu Jan 30 17:10:06 2003
+++ edited/fs/sysfs/dir.c Thu Mar 6 14:34:01 2003
@@ -71,7 +71,7 @@

void sysfs_remove_dir(struct kobject * kobj)
{
- struct list_head * node, * next;
+ struct list_head * node;
struct dentry * dentry = dget(kobj->dentry);
struct dentry * parent;

@@ -83,31 +83,28 @@
down(&parent->d_inode->i_sem);
down(&dentry->d_inode->i_sem);

- list_for_each_safe(node,next,&dentry->d_subdirs) {
- struct dentry * d = dget(list_entry(node,struct dentry,d_child));
- /**
- * Make sure dentry is still there
- */
- pr_debug(" o %s: ",d->d_name.name);
- if (d->d_inode) {
+ spin_lock(&dcache_lock);
+ node = dentry->d_subdirs.next;
+ while (node != &dentry->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");
+
/**
* Unlink and unhash.
*/
- simple_unlink(dentry->d_inode,d);
+ spin_unlock(&dcache_lock);
d_delete(d);
-
- /**
- * Drop reference from initial sysfs_get_dentry().
- */
+ simple_unlink(dentry->d_inode,d);
dput(d);
+ spin_lock(&dcache_lock);
}
- pr_debug(" done (%d)\n",atomic_read(&d->d_count));
- /**
- * drop reference from dget() above.
- */
- dput(d);
+ pr_debug(" done\n");
+ node = dentry->d_subdirs.next;
}

up(&dentry->d_inode->i_sem);

-
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