pidns: call pid_ns_prepare_proc() from create_pid_namespace()
Eric W. Biederman [Wed, 23 Mar 2011 23:43:13 +0000 (16:43 -0700)]
Reorganize proc_get_sb() so it can be called before the struct pid of the
first process is allocated.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/root.c
kernel/fork.c
kernel/pid_namespace.c

index ef9fa8e..e5e2bfa 100644 (file)
@@ -43,17 +43,6 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
        struct pid_namespace *ns;
        struct proc_inode *ei;
 
-       if (proc_mnt) {
-               /* Seed the root directory with a pid so it doesn't need
-                * to be special in base.c.  I would do this earlier but
-                * the only task alive when /proc is mounted the first time
-                * is the init_task and it doesn't have any pids.
-                */
-               ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
-               if (!ei->pid)
-                       ei->pid = find_get_pid(1);
-       }
-
        if (flags & MS_KERNMOUNT)
                ns = (struct pid_namespace *)data;
        else
@@ -71,16 +60,16 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
                        return ERR_PTR(err);
                }
 
-               ei = PROC_I(sb->s_root->d_inode);
-               if (!ei->pid) {
-                       rcu_read_lock();
-                       ei->pid = get_pid(find_pid_ns(1, ns));
-                       rcu_read_unlock();
-               }
-
                sb->s_flags |= MS_ACTIVE;
        }
 
+       ei = PROC_I(sb->s_root->d_inode);
+       if (!ei->pid) {
+               rcu_read_lock();
+               ei->pid = get_pid(find_pid_ns(1, ns));
+               rcu_read_unlock();
+       }
+
        return dget(sb->s_root);
 }
 
index 17aed43..457fff2 100644 (file)
@@ -1187,12 +1187,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                pid = alloc_pid(p->nsproxy->pid_ns);
                if (!pid)
                        goto bad_fork_cleanup_io;
-
-               if (clone_flags & CLONE_NEWPID) {
-                       retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
-                       if (retval < 0)
-                               goto bad_fork_free_pid;
-               }
        }
 
        p->pid = pid_nr(pid);
index a5aff94..e9c9adc 100644 (file)
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/acct.h>
 #include <linux/slab.h>
+#include <linux/proc_fs.h>
 
 #define BITS_PER_PAGE          (PAGE_SIZE*8)
 
@@ -72,7 +73,7 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
 {
        struct pid_namespace *ns;
        unsigned int level = parent_pid_ns->level + 1;
-       int i;
+       int i, err = -ENOMEM;
 
        ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
        if (ns == NULL)
@@ -96,14 +97,20 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
        for (i = 1; i < PIDMAP_ENTRIES; i++)
                atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
 
+       err = pid_ns_prepare_proc(ns);
+       if (err)
+               goto out_put_parent_pid_ns;
+
        return ns;
 
+out_put_parent_pid_ns:
+       put_pid_ns(parent_pid_ns);
 out_free_map:
        kfree(ns->pidmap[0].page);
 out_free:
        kmem_cache_free(pid_ns_cachep, ns);
 out:
-       return ERR_PTR(-ENOMEM);
+       return ERR_PTR(err);
 }
 
 static void destroy_pid_namespace(struct pid_namespace *ns)