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From: Eric W. Biederman on 20 Jun 2010 04:50

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(a)xmission.com>
---
fs/proc/root.c | 26 ++++++++------------------
kernel/fork.c | 6 ------
kernel/pid_namespace.c | 4 ++++
3 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 4258384..5f15353 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -43,17 +43,6 @@ static int proc_get_sb(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
@@ -71,17 +60,18 @@ static int proc_get_sb(struct file_system_type *fs_type,
return 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;
ns->proc_mnt = mnt;
}

+ /* Ensure the root directory has it's associated pid. */
+ 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();
+ }
+
simple_set_mnt(mnt, sb);
return 0;
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 8b85b17..3c2501d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1154,12 +1154,6 @@ 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);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a5aff94..b90e4ab 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -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)

@@ -96,6 +97,9 @@ 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);

+ if (pid_ns_prepare_proc(ns))
+ goto out_free_map;
+
return ns;

out_free_map:
--
1.6.5.2.143.g8cc62

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Prev: [PATCH 4/6] pidns: Don't allow new pids after the namespace is dead.
Next: sound fixes for 2.6.35-rc4