pids: Compute task_tgid using signal->leader_pid

The cost is the the same and this removes the need
to worry about complications that come from de_thread
and group_leader changing.

__task_pid_nr_ns has been updated to take advantage of this change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2017-09-26 12:45:33 -05:00
parent 1fb53567a3
commit 7a36094d61
9 changed files with 22 additions and 17 deletions

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@ -50,7 +50,6 @@ void foo(void)
DEFINE(IA64_TASK_BLOCKED_OFFSET,offsetof (struct task_struct, blocked));
DEFINE(IA64_TASK_CLEAR_CHILD_TID_OFFSET,offsetof (struct task_struct, clear_child_tid));
DEFINE(IA64_TASK_GROUP_LEADER_OFFSET, offsetof (struct task_struct, group_leader));
DEFINE(IA64_TASK_TGIDLINK_OFFSET, offsetof (struct task_struct, pids[PIDTYPE_PID].pid));
DEFINE(IA64_PID_LEVEL_OFFSET, offsetof (struct pid, level));
DEFINE(IA64_PID_UPID_OFFSET, offsetof (struct pid, numbers[0]));
@ -68,6 +67,7 @@ void foo(void)
DEFINE(IA64_SIGNAL_GROUP_STOP_COUNT_OFFSET,offsetof (struct signal_struct,
group_stop_count));
DEFINE(IA64_SIGNAL_SHARED_PENDING_OFFSET,offsetof (struct signal_struct, shared_pending));
DEFINE(IA64_SIGNAL_LEADER_PID_OFFSET, offsetof (struct signal_struct, leader_pid));
BLANK();

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@ -62,16 +62,16 @@ ENTRY(fsys_getpid)
.prologue
.altrp b6
.body
add r17=IA64_TASK_GROUP_LEADER_OFFSET,r16
add r17=IA64_TASK_SIGNAL_OFFSET,r16
;;
ld8 r17=[r17] // r17 = current->group_leader
ld8 r17=[r17] // r17 = current->signal
add r9=TI_FLAGS+IA64_TASK_SIZE,r16
;;
ld4 r9=[r9]
add r17=IA64_TASK_TGIDLINK_OFFSET,r17
add r17=IA64_SIGNAL_LEADER_PID_OFFSET,r17
;;
and r9=TIF_ALLWORK_MASK,r9
ld8 r17=[r17] // r17 = current->group_leader->pids[PIDTYPE_PID].pid
ld8 r17=[r17] // r17 = current->signal->leader_pid
;;
add r8=IA64_PID_LEVEL_OFFSET,r17
;;

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@ -57,6 +57,7 @@
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/delay.h>

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@ -12,6 +12,7 @@
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/module.h>
#include <linux/compat.h>
#include <linux/swap.h>

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@ -8,6 +8,7 @@
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/sched/user.h>
#include <linux/sched/signal.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/audit.h>

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@ -1202,11 +1202,6 @@ static inline struct pid *task_pid(struct task_struct *task)
return task->pids[PIDTYPE_PID].pid;
}
static inline struct pid *task_tgid(struct task_struct *task)
{
return task->group_leader->pids[PIDTYPE_PID].pid;
}
/*
* Without tasklist or RCU lock it is not safe to dereference
* the result of task_pgrp/task_session even if task == current,

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@ -564,6 +564,11 @@ struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
return task->pids[type].pid;
}
static inline struct pid *task_tgid(struct task_struct *task)
{
return task->signal->leader_pid;
}
static inline int get_nr_threads(struct task_struct *tsk)
{
return tsk->signal->nr_threads;

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@ -8,6 +8,7 @@
#include <linux/security.h>
#include <linux/pid.h>
#include <linux/nsproxy.h>
#include <linux/sched/signal.h>
/* Well, we should have at least one descriptor open
* to accept passed FDs 8)

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@ -421,13 +421,14 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
if (!ns)
ns = task_active_pid_ns(current);
if (likely(pid_alive(task))) {
if (type != PIDTYPE_PID) {
if (type == __PIDTYPE_TGID)
type = PIDTYPE_PID;
task = task->group_leader;
}
nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
struct pid *pid;
if (type == PIDTYPE_PID)
pid = task_pid(task);
else if (type == __PIDTYPE_TGID)
pid = task_tgid(task);
else
pid = rcu_dereference(task->group_leader->pids[type].pid);
nr = pid_nr_ns(pid, ns);
}
rcu_read_unlock();