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authorSteven Rostedt <srostedt@redhat.com>2009-04-25 00:39:40 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2009-06-15 21:30:24 -0700
commit56a83cc92991ed5bf76e224dd2ad53b5e9c00681 (patch)
tree5d786c4685ea40b2418dfab6896d461585f73d8e /fs/debugfs
parentc0afe7ba5e71d8ab66bc42f90b3e237581d3c509 (diff)
debugfs: dont stop on first failed recursive delete
debugfs: dont stop on first failed recursive delete While running a while loop of removing a module that removes a debugfs directory with debugfs_remove_recursive, and at the same time doing a while loop of cat of a file in that directory, I would hit a point where somehow the cat of the file caused the remove to fail. The result is that other files did not get removed when the module was removed. I simple read of one of those file can oops the kernel because the operations to the file no longer exist (removed by module). The funny thing is that the file being cat'ed was removed. It was the siblings that were not. I see in the code to debugfs_remove_recursive there's a test that checks if the child fails to bail out of the loop to prevent an infinite loop. What this patch does is to still try any siblings in that directory. If all the siblings fail, or there are no more siblings, then we exit the loop. This fixes the above symptom, but... This is no full proof. It makes the debugfs_remove_recursive a bit more robust, but it does not explain why the one file failed. There may be some kind of delay deletion that makes the debugfs think it did not succeed. So this patch is more of a fix for the symptom but not the disease. This patch still makes the debugfs_remove_recursive more robust and until I can find out why the bug exists, this patch will keep the kernel from oopsing in most cases. Even after the cause is found I think this change can stand on its own and should be kept. [ Impact: prevent kernel oops on module unload and reading debugfs files ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/debugfs')
-rw-r--r--fs/debugfs/inode.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 0662ba6de85..d22438ef767 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -403,6 +403,7 @@ void debugfs_remove_recursive(struct dentry *dentry)
}
child = list_entry(parent->d_subdirs.next, struct dentry,
d_u.d_child);
+ next_sibling:
/*
* If "child" isn't empty, walk down the tree and
@@ -417,6 +418,16 @@ void debugfs_remove_recursive(struct dentry *dentry)
__debugfs_remove(child, parent);
if (parent->d_subdirs.next == &child->d_u.d_child) {
/*
+ * Try the next sibling.
+ */
+ if (child->d_u.d_child.next != &parent->d_subdirs) {
+ child = list_entry(child->d_u.d_child.next,
+ struct dentry,
+ d_u.d_child);
+ goto next_sibling;
+ }
+
+ /*
* Avoid infinite loop if we fail to remove
* one dentry.
*/