Am Dienstag, 25. November 2008 schrieb Avi Kivity:
> I agree with your analysis, and also that the anon_inodes change is
> useful. If it's acceptable to the vfs/anon_inode maintainers, I'll
> apply the patch.
I think it is a good idea to strip the fs specific changes into a separate
patch for easier review:
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
There is an imbalance for anonymous inodes. If the fops->owner field is set,
the module reference count of owner is decreases on release.
("filp_close" --> "__fput" ---> "fops_put")
On the other hand, anon_inode_getfd does not increase the module reference
count of owner. This causes two problems:
- if owner is set, the module refcount goes negative
- if owner is not set, the module can be unloaded while code is running
This patch changes anon_inode_getfd to be symmetric regarding fops->owner
handling.
I have checked all existing users of anon_inode_getfd. Noone sets fops->owner,
thats why nobody has seen the module refcount negative.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
--- kvm.orig/fs/anon_inodes.c
+++ kvm/fs/anon_inodes.c
@@ -79,6 +79,9 @@ int anon_inode_getfd(const char *name, c
if (IS_ERR(anon_inode_inode))
return -ENODEV;
+ if (fops->owner && !try_module_get(fops->owner))
+ return -ENOENT;
+
error = get_unused_fd_flags(flags);
if (error < 0)
return error;
--
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