Isolate some explicit usage of task->tgid

With pid namespaces this field is now dangerous to use explicitly, so hide
it behind the helpers.

Also the pid and pgrp fields o task_struct and signal_struct are to be
deprecated.  Unfortunately this patch cannot be sent right now as this
leads to tons of warnings, so start isolating them, and deprecate later.

Actually the p->tgid == pid has to be changed to has_group_leader_pid(),
but Oleg pointed out that in case of posix cpu timers this is the same, and
thread_group_leader() is more preferable.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/exec.c b/fs/exec.c
index 007d0d8..2c942e2 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -841,8 +841,8 @@ static int de_thread(struct task_struct *tsk)
                 */
                tsk->start_time = leader->start_time;
 
-               BUG_ON(leader->tgid != tsk->tgid);
-               BUG_ON(tsk->pid == tsk->tgid);
+               BUG_ON(!same_thread_group(leader, tsk));
+               BUG_ON(has_group_leader_pid(tsk));
                /*
                 * An exec() starts a new thread group with the
                 * TGID of the previous thread group. Rehash the

diff --git a/fs/proc/base.c b/fs/proc/base.c
index db76360..9914828 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2553,7 +2553,7 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
        rcu_read_unlock();
        if (!task)
                goto out;
-       if (leader->tgid != task->tgid)
+       if (!same_thread_group(leader, task))
                goto out_drop_task;
 
        result = proc_task_instantiate(dir, dentry, task, NULL);

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f4d969e..eb2ae68 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1725,6 +1725,12 @@ static inline int has_group_leader_pid(struct task_struct *p)
        return p->pid == p->tgid;
 }
 
+static inline
+int same_thread_group(struct task_struct *p1, struct task_struct *p2)
+{
+       return p1->tgid == p2->tgid;
+}
+
 static inline struct task_struct *next_thread(const struct task_struct *p)
 {
        return list_entry(rcu_dereference(p->thread_group.next),

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index b53c8fc..68c9637 100644 (file)
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -21,8 +21,8 @@ static int check_clock(const clockid_t which_clock)
 
        read_lock(&tasklist_lock);
        p = find_task_by_pid(pid);
-       if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?
-                  p->tgid != current->tgid : p->tgid != pid)) {
+       if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
+                  same_thread_group(p, current) : thread_group_leader(p))) {
                error = -EINVAL;
        }
        read_unlock(&tasklist_lock);
@@ -308,13 +308,13 @@ int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
                p = find_task_by_pid(pid);
                if (p) {
                        if (CPUCLOCK_PERTHREAD(which_clock)) {
-                               if (p->tgid == current->tgid) {
+                               if (same_thread_group(p, current)) {
                                        error = cpu_clock_sample(which_clock,
                                                                 p, &rtn);
                                }
                        } else {
                                read_lock(&tasklist_lock);
-                               if (p->tgid == pid && p->signal) {
+                               if (thread_group_leader(p) && p->signal) {
                                        error =
                                            cpu_clock_sample_group(which_clock,
                                                                   p, &rtn);
@@ -355,7 +355,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
                        p = current;
                } else {
                        p = find_task_by_pid(pid);
-                       if (p && p->tgid != current->tgid)
+                       if (p && !same_thread_group(p, current))
                                p = NULL;
                }
        } else {
@@ -363,7 +363,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
                        p = current->group_leader;
                } else {
                        p = find_task_by_pid(pid);
-                       if (p && p->tgid != pid)
+                       if (p && !thread_group_leader(p))
                                p = NULL;
                }
        }

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index d11f579..35b4bbf 100644 (file)
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -404,7 +404,7 @@ static struct task_struct * good_sigevent(sigevent_t * event)
 
        if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
                (!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
-                rtn->tgid != current->tgid ||
+                !same_thread_group(rtn, current) ||
                 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
                return NULL;
 
@@ -608,7 +608,7 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
                spin_lock(&timr->it_lock);
 
                if ((timr->it_id != timer_id) || !(timr->it_process) ||
-                               timr->it_process->tgid != current->tgid) {
+                               !same_thread_group(timr->it_process, current)) {
                        spin_unlock(&timr->it_lock);
                        spin_unlock_irqrestore(&idr_lock, *flags);
                        timr = NULL;

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index b0ace60..7c76f2f 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -169,7 +169,7 @@ int ptrace_attach(struct task_struct *task)
        retval = -EPERM;
        if (task->pid <= 1)
                goto out;
-       if (task->tgid == current->tgid)
+       if (same_thread_group(task, current))
                goto out;
 
 repeat:

diff --git a/kernel/signal.c b/kernel/signal.c
index 783b33a..08364e7 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1150,7 +1150,7 @@ static int kill_something_info(int sig, struct siginfo *info, int pid)
 
                read_lock(&tasklist_lock);
                for_each_process(p) {
-                       if (p->pid > 1 && p->tgid != current->tgid) {
+                       if (p->pid > 1 && !same_thread_group(p, current)) {
                                int err = group_send_sig_info(sig, info, p);
                                ++count;
                                if (err != -EPERM)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index a7cb4c4..e3778f1 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -326,7 +326,7 @@ static int oom_kill_task(struct task_struct *p)
         * to memory reserves though, otherwise we might deplete all memory.
         */
        do_each_thread(g, q) {
-               if (q->mm == mm && q->tgid != p->tgid)
+               if (q->mm == mm && !same_thread_group(q, p))
                        force_sig(SIGKILL, q);
        } while_each_thread(g, q);