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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-09 13:55:51 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-09 13:55:51 -0800
commit78833dd70602be6b71ef34225f708b1e500947dc (patch)
tree807050f760ccc7305b194d7568ebf98737076a40
parenta5abba989deceb731047425812d268daf7536575 (diff)
parentb306419ae08d9def53f2142a37cc0a58622307a8 (diff)
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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: nd->inode is not set on the second attempt in path_walk() unfuck proc_sysctl ->d_compare() minimal fix for do_filp_open() race
-rw-r--r--fs/namei.c14
-rw-r--r--fs/proc/inode.c8
-rw-r--r--fs/proc/proc_sysctl.c7
-rw-r--r--include/linux/sysctl.h14
-rw-r--r--kernel/sysctl.c15
5 files changed, 42 insertions, 16 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 0087cf9c2c6b..a4689eb2df28 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1546,6 +1546,7 @@ static int path_walk(const char *name, struct nameidata *nd)
/* nd->path had been dropped */
current->total_link_count = 0;
nd->path = save;
+ nd->inode = save.dentry->d_inode;
path_get(&nd->path);
nd->flags |= LOOKUP_REVAL;
result = link_path_walk(name, nd);
@@ -2455,22 +2456,29 @@ struct file *do_filp_open(int dfd, const char *pathname,
/* !O_CREAT, simple open */
error = do_path_lookup(dfd, pathname, flags, &nd);
if (unlikely(error))
- goto out_filp;
+ goto out_filp2;
error = -ELOOP;
if (!(nd.flags & LOOKUP_FOLLOW)) {
if (nd.inode->i_op->follow_link)
- goto out_path;
+ goto out_path2;
}
error = -ENOTDIR;
if (nd.flags & LOOKUP_DIRECTORY) {
if (!nd.inode->i_op->lookup)
- goto out_path;
+ goto out_path2;
}
audit_inode(pathname, nd.path.dentry);
filp = finish_open(&nd, open_flag, acc_mode);
+out2:
release_open_intent(&nd);
return filp;
+out_path2:
+ path_put(&nd.path);
+out_filp2:
+ filp = ERR_PTR(error);
+ goto out2;
+
creat:
/* OK, have to create the file. Find the parent. */
error = path_init_rcu(dfd, pathname,
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 176ce4cda68a..d6a7ca1fdac5 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -27,6 +27,7 @@
static void proc_evict_inode(struct inode *inode)
{
struct proc_dir_entry *de;
+ struct ctl_table_header *head;
truncate_inode_pages(&inode->i_data, 0);
end_writeback(inode);
@@ -38,8 +39,11 @@ static void proc_evict_inode(struct inode *inode)
de = PROC_I(inode)->pde;
if (de)
pde_put(de);
- if (PROC_I(inode)->sysctl)
- sysctl_head_put(PROC_I(inode)->sysctl);
+ head = PROC_I(inode)->sysctl;
+ if (head) {
+ rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
+ sysctl_head_put(head);
+ }
}
struct vfsmount *proc_mnt;
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 09a1f92a34ef..8eb2522111c5 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -408,15 +408,18 @@ static int proc_sys_compare(const struct dentry *parent,
const struct dentry *dentry, const struct inode *inode,
unsigned int len, const char *str, const struct qstr *name)
{
+ struct ctl_table_header *head;
/* Although proc doesn't have negative dentries, rcu-walk means
* that inode here can be NULL */
+ /* AV: can it, indeed? */
if (!inode)
- return 0;
+ return 1;
if (name->len != len)
return 1;
if (memcmp(name->name, str, len))
return 1;
- return !sysctl_is_seen(PROC_I(inode)->sysctl);
+ head = rcu_dereference(PROC_I(inode)->sysctl);
+ return !head || !sysctl_is_seen(head);
}
static const struct dentry_operations proc_sys_dentry_operations = {
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;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0f1bd83db985..4eed0af5d144 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -194,9 +194,9 @@ static int sysrq_sysctl_handler(ctl_table *table, int write,
static struct ctl_table root_table[];
static struct ctl_table_root sysctl_table_root;
static struct ctl_table_header root_table_header = {
- .count = 1,
+ {{.count = 1,
.ctl_table = root_table,
- .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),
+ .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
.root = &sysctl_table_root,
.set = &sysctl_table_root.default_set,
};
@@ -1567,11 +1567,16 @@ void sysctl_head_get(struct ctl_table_header *head)
spin_unlock(&sysctl_lock);
}
+static void free_head(struct rcu_head *rcu)
+{
+ kfree(container_of(rcu, struct ctl_table_header, rcu));
+}
+
void sysctl_head_put(struct ctl_table_header *head)
{
spin_lock(&sysctl_lock);
if (!--head->count)
- kfree(head);
+ call_rcu(&head->rcu, free_head);
spin_unlock(&sysctl_lock);
}
@@ -1948,10 +1953,10 @@ void unregister_sysctl_table(struct ctl_table_header * header)
start_unregistering(header);
if (!--header->parent->count) {
WARN_ON(1);
- kfree(header->parent);
+ call_rcu(&header->parent->rcu, free_head);
}
if (!--header->count)
- kfree(header);
+ call_rcu(&header->rcu, free_head);
spin_unlock(&sysctl_lock);
}