1 files changed, 16 insertions, 1 deletions

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index a7708b7c957..47b474b572c 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -525,20 +525,32 @@ static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
 
 static int proc_sys_open(struct inode *inode, struct file *filp)
 {
+        struct ctl_table_header *head = grab_header(inode);
         struct ctl_table *table = PROC_I(inode)->sysctl_entry;
 
+        /* sysctl was unregistered */
+        if (IS_ERR(head))
+                return PTR_ERR(head);
+
         if (table->poll)
                 filp->private_data = proc_sys_poll_event(table->poll);
 
+        sysctl_head_finish(head);
+
         return 0;
 }
 
 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
 {
         struct inode *inode = filp->f_path.dentry->d_inode;
+        struct ctl_table_header *head = grab_header(inode);
         struct ctl_table *table = PROC_I(inode)->sysctl_entry;
-        unsigned long event = (unsigned long)filp->private_data;
         unsigned int ret = DEFAULT_POLLMASK;
+        unsigned long event;
+
+        /* sysctl was unregistered */
+        if (IS_ERR(head))
+                return POLLERR | POLLHUP;
 
         if (!table->proc_handler)
                 goto out;
@@ -546,6 +558,7 @@ static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
         if (!table->poll)
                 goto out;
 
+        event = (unsigned long)filp->private_data;
         poll_wait(filp, &table->poll->wait, wait);
 
         if (event != atomic_read(&table->poll->event)) {
@@ -554,6 +567,8 @@ static unsigned int proc_sys_poll(struct file *filp, poll_table *wait)
         }
 
 out:
+        sysctl_head_finish(head);
+
         return ret;
 }