3 files changed, 34 insertions, 3 deletions

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 20e5c4509a43..47b7a20d45eb 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -19,6 +19,7 @@
 #include <linux/idr.h>
 #include <linux/namei.h>
 #include <linux/bitops.h>
+#include <linux/spinlock.h>
 #include <asm/uaccess.h>
 
 #include "internal.h"
@@ -29,6 +30,8 @@ static ssize_t proc_file_write(struct file *file, const char __user *buffer,
                                size_t count, loff_t *ppos);
 static loff_t proc_file_lseek(struct file *, loff_t, int);
 
+DEFINE_SPINLOCK(proc_subdir_lock);
+
 int proc_match(int len, const char *name, struct proc_dir_entry *de)
 {
         if (de->namelen != len)
@@ -277,7 +280,9 @@ static int xlate_proc_name(const char *name,
         const char              *cp = name, *next;
         struct proc_dir_entry   *de;
         int                     len;
+        int                     rtn = 0;
 
+        spin_lock(&proc_subdir_lock);
         de = &proc_root;
         while (1) {
                 next = strchr(cp, '/');
@@ -289,13 +294,17 @@ static int xlate_proc_name(const char *name,
                         if (proc_match(len, cp, de))
                                 break;
                 }
-                if (!de)
-                        return -ENOENT;
+                if (!de) {
+                        rtn = -ENOENT;
+                        goto out;
+                }
                 cp += len + 1;
         }
         *residual = cp;
         *ret = de;
-        return 0;
+out:
+        spin_unlock(&proc_subdir_lock);
+        return rtn;
 }
 
 static DEFINE_IDR(proc_inum_idr);
@@ -380,6 +389,7 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
         int error = -ENOENT;
 
         lock_kernel();
+        spin_lock(&proc_subdir_lock);
         de = PDE(dir);
         if (de) {
                 for (de = de->subdir; de ; de = de->next) {
@@ -388,12 +398,15 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
                         if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
                                 unsigned int ino = de->low_ino;
 
+                                spin_unlock(&proc_subdir_lock);
                                 error = -EINVAL;
                                 inode = proc_get_inode(dir->i_sb, ino, de);
+                                spin_lock(&proc_subdir_lock);
                                 break;
                         }
                 }
         }
+        spin_unlock(&proc_subdir_lock);
         unlock_kernel();
 
         if (inode) {
@@ -447,11 +460,13 @@ int proc_readdir(struct file * filp,
                         filp->f_pos++;
                         /* fall through */
                 default:
+                        spin_lock(&proc_subdir_lock);
                         de = de->subdir;
                         i -= 2;
                         for (;;) {
                                 if (!de) {
                                         ret = 1;
+                                        spin_unlock(&proc_subdir_lock);
                                         goto out;
                                 }
                                 if (!i)
@@ -461,12 +476,16 @@ int proc_readdir(struct file * filp,
                         }
 
                         do {
+                                /* filldir passes info to user space */
+                                spin_unlock(&proc_subdir_lock);
                                 if (filldir(dirent, de->name, de->namelen, filp->f_pos,
                                             de->low_ino, de->mode >> 12) < 0)
                                         goto out;
+                                spin_lock(&proc_subdir_lock);
                                 filp->f_pos++;
                                 de = de->next;
                         } while (de);
+                        spin_unlock(&proc_subdir_lock);
         }
         ret = 1;
 out:    unlock_kernel();
@@ -500,9 +519,13 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
         if (i == 0)
                 return -EAGAIN;
         dp->low_ino = i;
+
+        spin_lock(&proc_subdir_lock);
         dp->next = dir->subdir;
         dp->parent = dir;
         dir->subdir = dp;
+        spin_unlock(&proc_subdir_lock);
+
         if (S_ISDIR(dp->mode)) {
                 if (dp->proc_iops == NULL) {
                         dp->proc_fops = &proc_dir_operations;
@@ -694,6 +717,8 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
         if (!parent && xlate_proc_name(name, &parent, &fn) != 0)
                 goto out;
         len = strlen(fn);
+
+        spin_lock(&proc_subdir_lock);
         for (p = &parent->subdir; *p; p=&(*p)->next ) {
                 if (!proc_match(len, fn, *p))
                         continue;
@@ -714,6 +739,7 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
                 }
                 break;
         }
+        spin_unlock(&proc_subdir_lock);
 out:
         return;
 }
diff --git a/fs/proc/proc_devtree.c b/fs/proc/proc_devtree.c
index 9bdd077d6f55..596b4b4f1cc8 100644
--- a/fs/proc/proc_devtree.c
+++ b/fs/proc/proc_devtree.c
@@ -136,9 +136,11 @@ void proc_device_tree_add_node(struct device_node *np,
                  * properties are quite unimportant for us though, thus we
                  * simply "skip" them here, but we do have to check.
                  */
+                spin_lock(&proc_subdir_lock);
                 for (ent = de->subdir; ent != NULL; ent = ent->next)
                         if (!strcmp(ent->name, pp->name))
                                 break;
+                spin_unlock(&proc_subdir_lock);
                 if (ent != NULL) {
                         printk(KERN_WARNING "device-tree: property \"%s\" name"
                                " conflicts with node in %s\n", pp->name,
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index aa6322d45198..6b12b0f661b4 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -4,6 +4,7 @@
 #include <linux/config.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
+#include <linux/spinlock.h>
 #include <asm/atomic.h>
 
 /*
@@ -92,6 +93,8 @@ extern struct proc_dir_entry *proc_bus;
 extern struct proc_dir_entry *proc_root_driver;
 extern struct proc_dir_entry *proc_root_kcore;
 
+extern spinlock_t proc_subdir_lock;
+
 extern void proc_root_init(void);
 extern void proc_misc_init(void);