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Message-ID: <m11vc2qed4.fsf_-_@fess.ebiederm.org>
Date: Sun, 20 Jun 2010 01:48:07 -0700
From: ebiederm@...ssion.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Louis Rilling <louis.rilling@...labs.com>,
Pavel Emelyanov <xemul@...nvz.org>,
Linux Containers <containers@...ts.osdl.org>,
linux-kernel@...r.kernel.org, Daniel Lezcano <dlezcano@...ibm.com>
Subject: [PATCH 5/6] 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.
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
arch/powerpc/platforms/cell/spufs/sched.c | 2 +-
arch/um/drivers/mconsole_kern.c | 2 +-
fs/proc/root.c | 2 +-
kernel/cgroup.c | 3 +--
kernel/perf_event.c | 2 +-
kernel/pid.c | 8 ++++----
kernel/signal.c | 9 ++++-----
kernel/sysctl_binary.c | 2 +-
8 files changed, 14 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 0b04662..82e26a0 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -1095,7 +1095,7 @@ 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 de317d0..77787d2 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -125,7 +125,7 @@ void mconsole_log(struct mc_request *req)
void mconsole_proc(struct mc_request *req)
{
struct nameidata nd;
- struct vfsmount *mnt = current->nsproxy->pid_ns->proc_mnt;
+ struct vfsmount *mnt = task_active_pid_ns(current)->proc_mnt;
struct file *file;
int n, err;
char *ptr = req->request.data, *buf;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 310ac20..7e154fb 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -46,7 +46,7 @@ static int proc_get_sb(struct file_system_type *fs_type,
if (flags & MS_KERNMOUNT)
ns = (struct pid_namespace *)data;
else
- ns = current->nsproxy->pid_ns;
+ ns = task_active_pid_ns(current);
sb = sget(fs_type, proc_test_super, proc_set_super, ns);
if (IS_ERR(sb))
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3ac6f5b..a162b00 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2650,8 +2650,7 @@ 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
* the last ref-holder is trying to remove l from the list at the same
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index ff86c55..42efe59 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4843,7 +4843,7 @@ perf_event_alloc(struct perf_event_attr *attr,
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/pid.c b/kernel/pid.c
index e1f26ec..0bbccc2 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -309,7 +309,7 @@ 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);
@@ -391,7 +391,7 @@ 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)
@@ -443,7 +443,7 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *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);
@@ -454,7 +454,7 @@ 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 906ae5a..bb90743 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1458,16 +1458,15 @@ int do_notify_parent(struct task_struct *tsk, int sig)
* we are under tasklist_lock here so our parent is tied to
* us and cannot exit and release its namespace.
*
- * the only it can is to switch its nsproxy with sys_unshare,
- * bu uncharing pid namespaces is not allowed, so we'll always
- * see relevant namespace
+ * The only it can is to switch its nsproxy with sys_unshare,
+ * but we use the pid_namespace for task_pid which never changes.
*
* write_lock() currently calls preempt_disable() which is the
* same as rcu_read_lock(), but according to Oleg, this is not
* correct to rely on this
*/
rcu_read_lock();
- info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
+ info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
info.si_uid = __task_cred(tsk)->uid;
rcu_read_unlock();
@@ -1538,7 +1537,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
* see comment in do_notify_parent() abot the following 3 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 = __task_cred(tsk)->uid;
rcu_read_unlock();
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 1357c57..da4eb82 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -1350,7 +1350,7 @@ 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;
result = vfs_path_lookup(mnt->mnt_root, mnt, pathname, 0, &nd);
if (result)
goto out_putname;
--
1.6.5.2.143.g8cc62
--
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