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>

4 files changed, 10 insertions, 10 deletions

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index b53c8fcd9d82..68c96376e84a 100644
--- 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 d11f579d189a..35b4bbfc78ff 100644
--- 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 b0ace60ce596..7c76f2ffaeaa 100644
--- 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 783b33a0af06..08364e75bb58 100644
--- 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)