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authorAl Viro <viro@zeniv.linux.org.uk>2011-03-08 01:25:28 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2011-03-08 02:22:27 -0500
commitdfef6dcd35cb4a251f6322ca9b2c06f0bb1aa1f4 (patch)
tree65e8a25d4ed913658db35c4b97ab0a021c2124eb /include
parent1858efd471624ecb37e6b5462cab8076f47d1cee (diff)
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')
-rw-r--r--include/linux/sysctl.h14
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;

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