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author | Al Viro <viro@zeniv.linux.org.uk> | 2011-03-08 01:25:28 -0500 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-03-08 02:22:27 -0500 |
commit | dfef6dcd35cb4a251f6322ca9b2c06f0bb1aa1f4 (patch) | |
tree | 65e8a25d4ed913658db35c4b97ab0a021c2124eb /include/linux/sysctl.h | |
parent | 1858efd471624ecb37e6b5462cab8076f47d1cee (diff) | |
download | linux-stable-dfef6dcd35cb4a251f6322ca9b2c06f0bb1aa1f4.tar.gz linux-stable-dfef6dcd35cb4a251f6322ca9b2c06f0bb1aa1f4.tar.bz2 linux-stable-dfef6dcd35cb4a251f6322ca9b2c06f0bb1aa1f4.zip |
unfuck proc_sysctl ->d_compare()
a) struct inode is not going to be freed under ->d_compare();
however, the thing PROC_I(inode)->sysctl points to just might.
Fortunately, it's enough to make freeing that sucker delayed,
provided that we don't step on its ->unregistering, clear
the pointer to it in PROC_I(inode) before dropping the reference
and check if it's NULL in ->d_compare().
b) I'm not sure that we *can* walk into NULL inode here (we recheck
dentry->seq between verifying that it's still hashed / fetching
dentry->d_inode and passing it to ->d_compare() and there's no
negative hashed dentries in /proc/sys/*), but if we can walk into
that, we really should not have ->d_compare() return 0 on it!
Said that, I really suspect that this check can be simply killed.
Nick?
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/sysctl.h')
-rw-r--r-- | include/linux/sysctl.h | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 7bb5cb64f3b8..bb7c2b086fa4 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -25,6 +25,7 @@ #include <linux/kernel.h> #include <linux/types.h> #include <linux/compiler.h> +#include <linux/rcupdate.h> struct completion; @@ -1037,10 +1038,15 @@ struct ctl_table_root { struct ctl_table trees. */ struct ctl_table_header { - struct ctl_table *ctl_table; - struct list_head ctl_entry; - int used; - int count; + union { + struct { + struct ctl_table *ctl_table; + struct list_head ctl_entry; + int used; + int count; + }; + struct rcu_head rcu; + }; struct completion *unregistering; struct ctl_table *ctl_table_arg; struct ctl_table_root *root; |