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

diff --git a/fs/namei.c b/fs/namei.c
index 0087cf9c2c6bccaf99000fbd0bfe95257549d81b..a4689eb2df285eb513d049fa0c5122f1edd4b198 100644 (file)
--- 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 176ce4cda68a113d10e3107830730848dc0cd7f5..d6a7ca1fdac53dfdf47fb7109207c0ec7597a3e7 100644 (file)
--- 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 09a1f92a34ef2fce52b07cf394d040708e86a22b..8eb2522111c5d8033a404a0d366832ea66e2d3fc 100644 (file)
--- 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 7bb5cb64f3b84798db8023be585755d94af785a0..bb7c2b086fa458845ca675b93f2a51bf35f8e81e 100644 (file)
--- 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 0f1bd83db98523333b9fabde37d200512b20b77e..4eed0af5d1442c6ec4cfbd2f6c82e48debdca677 100644 (file)
--- 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);
 }