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Commit e3a2a0d4 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Avi Kivity
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anon_inodes: use fops->owner for module refcount



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. The refcounting was
tested with a patched and unpatched KVM module.(see patch 2/2) I also did an
epoll_open/close test.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent e93353c9
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