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authorOleg Nesterov <oleg@redhat.com>2009-04-02 16:58:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-02 19:05:02 -0700
commit52ee2dfdd4f51cf422ea6a96a0846dc94244aa37 (patch)
treee15753e01d2c2fbe980edc45f78a9ae77d2cf891
parent2ae448efc87df6d328f5835969076c7f9fce59c3 (diff)
pids: refactor vnr/nr_ns helpers to make them safe
Inho, the safety rules for vnr/nr_ns helpers are horrible and buggy. task_pid_nr_ns(task) needs rcu/tasklist depending on task == current. As for "special" pids, vnr/nr_ns helpers always need rcu. However, if task != current, they are unsafe even under rcu lock, we can't trust task->group_leader without the special checks. And almost every helper has a callsite which needs a fix. Also, it is a bit annoying that the implementations of, say, task_pgrp_vnr() and task_pgrp_nr_ns() are not "symmetrical". This patch introduces the new helper, __task_pid_nr_ns(), which is always safe to use, and turns all other helpers into the trivial wrappers. After this I'll send another patch which converts task_tgid_xxx() as well, they're are a bit special. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Louis Rilling <Louis.Rilling@kerlabs.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/sched.h27
-rw-r--r--kernel/pid.c31
2 files changed, 36 insertions, 22 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 722dd313bf8..49df878a0ca 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1519,17 +1519,23 @@ struct pid_namespace;
*
* see also pid_nr() etc in include/linux/pid.h
*/
+pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
+ struct pid_namespace *ns);
static inline pid_t task_pid_nr(struct task_struct *tsk)
{
return tsk->pid;
}
-pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);
+static inline pid_t task_pid_nr_ns(struct task_struct *tsk,
+ struct pid_namespace *ns)
+{
+ return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
+}
static inline pid_t task_pid_vnr(struct task_struct *tsk)
{
- return pid_vnr(task_pid(tsk));
+ return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
}
@@ -1551,11 +1557,15 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk)
return tsk->signal->__pgrp;
}
-pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);
+static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
+ struct pid_namespace *ns)
+{
+ return __task_pid_nr_ns(tsk, PIDTYPE_PGID, ns);
+}
static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
{
- return pid_vnr(task_pgrp(tsk));
+ return __task_pid_nr_ns(tsk, PIDTYPE_PGID, NULL);
}
@@ -1564,14 +1574,17 @@ static inline pid_t task_session_nr(struct task_struct *tsk)
return tsk->signal->__session;
}
-pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);
+static inline pid_t task_session_nr_ns(struct task_struct *tsk,
+ struct pid_namespace *ns)
+{
+ return __task_pid_nr_ns(tsk, PIDTYPE_SID, ns);
+}
static inline pid_t task_session_vnr(struct task_struct *tsk)
{
- return pid_vnr(task_session(tsk));
+ return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
}
-
/**
* pid_alive - check that a task structure is not stale
* @p: Task structure to be checked.
diff --git a/kernel/pid.c b/kernel/pid.c
index 6628abcc520..b2e5f78fd28 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -452,11 +452,24 @@ pid_t pid_vnr(struct pid *pid)
}
EXPORT_SYMBOL_GPL(pid_vnr);
-pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
+ struct pid_namespace *ns)
{
- return pid_nr_ns(task_pid(tsk), ns);
+ pid_t nr = 0;
+
+ rcu_read_lock();
+ if (!ns)
+ ns = current->nsproxy->pid_ns;
+ if (likely(pid_alive(task))) {
+ if (type != PIDTYPE_PID)
+ task = task->group_leader;
+ nr = pid_nr_ns(task->pids[type].pid, ns);
+ }
+ rcu_read_unlock();
+
+ return nr;
}
-EXPORT_SYMBOL(task_pid_nr_ns);
+EXPORT_SYMBOL(__task_pid_nr_ns);
pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
{
@@ -464,18 +477,6 @@ pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
}
EXPORT_SYMBOL(task_tgid_nr_ns);
-pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
-{
- return pid_nr_ns(task_pgrp(tsk), ns);
-}
-EXPORT_SYMBOL(task_pgrp_nr_ns);
-
-pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
-{
- return pid_nr_ns(task_session(tsk), ns);
-}
-EXPORT_SYMBOL(task_session_nr_ns);
-
struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
{
return ns_of_pid(task_pid(tsk));