pidns: Use task_active_pid_ns where appropriate

The expressions tsk->nsproxy->pid_ns and task_active_pid_ns
aka ns_of_pid(task_pid(tsk)) should have the same number of
cache line misses with the practical difference that
ns_of_pid(task_pid(tsk)) is released later in a processes life.

Furthermore by using task_active_pid_ns it becomes trivial
to write an unshare implementation for the the pid namespace.

So I have used task_active_pid_ns everywhere I can.

In fork since the pid has not yet been attached to the
process I use ns_of_pid, to achieve the same effect.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

12 files changed, 16 insertions, 15 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 965d381abd75..25db92a8e1cf 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -1094,7 +1094,7 @@ static int show_spu_loadavg(struct seq_file *s, void *private)
                 LOAD_INT(c), LOAD_FRAC(c),
                 count_active_contexts(),
                 atomic_read(&nr_spu_contexts),
-                current->nsproxy->pid_ns->last_pid);
+                task_active_pid_ns(current)->last_pid);
         return 0;
 }
 
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 79ccfe6c7078..7fc71c628267 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -123,7 +123,7 @@ void mconsole_log(struct mc_request *req)
 
 void mconsole_proc(struct mc_request *req)
 {
-        struct vfsmount *mnt = current->nsproxy->pid_ns->proc_mnt;
+        struct vfsmount *mnt = task_active_pid_ns(current)->proc_mnt;
         char *buf;
         int len;
         struct file *file;
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 5d4610babd8a..a97bbcd1c9ea 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -33,6 +33,7 @@
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
+#include <linux/pid_namespace.h>
 
 #include "binder.h"
 
@@ -2344,7 +2345,7 @@ retry:
                 if (t->from) {
                         struct task_struct *sender = t->from->proc->tsk;
                         tr.sender_pid = task_tgid_nr_ns(sender,
-                                                        current->nsproxy->pid_ns);
+                                                        task_active_pid_ns(current));
                 } else {
                         tr.sender_pid = 0;
                 }
diff --git a/fs/hppfs/hppfs.c b/fs/hppfs/hppfs.c
index 78f21f8dc2ec..43b315f2002b 100644
--- a/fs/hppfs/hppfs.c
+++ b/fs/hppfs/hppfs.c
@@ -710,7 +710,7 @@ static int hppfs_fill_super(struct super_block *sb, void *d, int silent)
         struct vfsmount *proc_mnt;
         int err = -ENOENT;
 
-        proc_mnt = mntget(current->nsproxy->pid_ns->proc_mnt);
+        proc_mnt = mntget(task_active_pid_ns(current)->proc_mnt);
         if (IS_ERR(proc_mnt))
                 goto out;
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 13ef6247e7a3..fc1609321a78 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -106,7 +106,7 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
                 ns = (struct pid_namespace *)data;
                 options = NULL;
         } else {
-                ns = current->nsproxy->pid_ns;
+                ns = task_active_pid_ns(current);
                 options = data;
         }
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index f24f724620dd..0dbfba2efa77 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3390,7 +3390,7 @@ static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
 {
         struct cgroup_pidlist *l;
         /* don't need task_nsproxy() if we're looking at ourself */
-        struct pid_namespace *ns = current->nsproxy->pid_ns;
+        struct pid_namespace *ns = task_active_pid_ns(current);
 
         /*
          * We can't drop the pidlist_mutex before taking the l->mutex in case
diff --git a/kernel/events/core.c b/kernel/events/core.c
index dbccf83c134d..738f3564e83b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6155,7 +6155,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 
         event->parent           = parent_event;
 
-        event->ns               = get_pid_ns(current->nsproxy->pid_ns);
+        event->ns               = get_pid_ns(task_active_pid_ns(current));
         event->id               = atomic64_inc_return(&perf_event_id);
 
         event->state            = PERF_EVENT_STATE_INACTIVE;
diff --git a/kernel/fork.c b/kernel/fork.c
index 8b20ab7d3aa2..7798c247f4b9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1442,7 +1442,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
                 if (thread_group_leader(p)) {
                         if (is_child_reaper(pid))
-                                p->nsproxy->pid_ns->child_reaper = p;
+                                ns_of_pid(pid)->child_reaper = p;
 
                         p->signal->leader_pid = pid;
                         p->signal->tty = tty_kref_get(current->signal->tty);
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index ca27d2c5264d..acc92680381a 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -84,7 +84,7 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
                 goto out_ipc;
         }
 
-        new_nsp->pid_ns = copy_pid_ns(flags, task_cred_xxx(tsk, user_ns), task_active_pid_ns(tsk));
+        new_nsp->pid_ns = copy_pid_ns(flags, task_cred_xxx(tsk, user_ns), tsk->nsproxy->pid_ns);
         if (IS_ERR(new_nsp->pid_ns)) {
                 err = PTR_ERR(new_nsp->pid_ns);
                 goto out_pid;
diff --git a/kernel/pid.c b/kernel/pid.c
index 2a624f1486e1..3a5f238c1ca0 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -345,7 +345,7 @@ EXPORT_SYMBOL_GPL(find_pid_ns);
 
 struct pid *find_vpid(int nr)
 {
-        return find_pid_ns(nr, current->nsproxy->pid_ns);
+        return find_pid_ns(nr, task_active_pid_ns(current));
 }
 EXPORT_SYMBOL_GPL(find_vpid);
 
@@ -429,7 +429,7 @@ struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
 
 struct task_struct *find_task_by_vpid(pid_t vnr)
 {
-        return find_task_by_pid_ns(vnr, current->nsproxy->pid_ns);
+        return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
 }
 
 struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
@@ -484,7 +484,7 @@ EXPORT_SYMBOL_GPL(pid_nr_ns);
 
 pid_t pid_vnr(struct pid *pid)
 {
-        return pid_nr_ns(pid, current->nsproxy->pid_ns);
+        return pid_nr_ns(pid, task_active_pid_ns(current));
 }
 EXPORT_SYMBOL_GPL(pid_vnr);
 
@@ -495,7 +495,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
 
         rcu_read_lock();
         if (!ns)
-                ns = current->nsproxy->pid_ns;
+                ns = task_active_pid_ns(current);
         if (likely(pid_alive(task))) {
                 if (type != PIDTYPE_PID)
                         task = task->group_leader;
diff --git a/kernel/signal.c b/kernel/signal.c
index 0af8868525d6..b2445d86f226 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1752,7 +1752,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
          * see comment in do_notify_parent() about the following 4 lines
          */
         rcu_read_lock();
-        info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
+        info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
         info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
         rcu_read_unlock();
 
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 65bdcf198d4e..5a6384450501 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -1344,7 +1344,7 @@ static ssize_t binary_sysctl(const int *name, int nlen,
                 goto out_putname;
         }
 
-        mnt = current->nsproxy->pid_ns->proc_mnt;
+        mnt = task_active_pid_ns(current)->proc_mnt;
         file = file_open_root(mnt->mnt_root, mnt, pathname, flags);
         result = PTR_ERR(file);
         if (IS_ERR(file))