[PATCH 3/7] pid: use the CONST_CAST macro instead to write to const task_struct::pid

[Richard Guy Briggs]

The CONST_CAST macro is a cleaner and more reliable way to write to the const
task_struct::pid.

Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
---
 fs/exec.c     |    4 +---
 kernel/fork.c |    5 +----
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index a6b585e..1d2369d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -906,8 +906,6 @@ static int de_thread(struct task_struct *tsk)
 	 */
 	if (!thread_group_leader(tsk)) {
 		struct task_struct *leader = tsk->group_leader;
-		/* tast_struct::pid is const pid_t, hence the ugly cast */
-		pid_t *pid_p = (pid_t*)&(tsk->pid);
 
 		sig->notify_count = -1;	/* for exit_notify() */
 		for (;;) {
@@ -950,7 +948,7 @@ static int de_thread(struct task_struct *tsk)
 		 * Note: The old leader also uses this pid until release_task
 		 *       is called.  Odd but simple and correct.
 		 */
-		*pid_p = leader->pid;
+		CONST_CAST(pid_t, tsk->pid) = leader->pid;
 		change_pid(tsk, PIDTYPE_PID, task_pid(leader));
 		transfer_pid(leader, tsk, PIDTYPE_PGID);
 		transfer_pid(leader, tsk, PIDTYPE_SID);
diff --git a/kernel/fork.c b/kernel/fork.c
index 296e564..207c543 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1135,7 +1135,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 {
 	int retval;
 	struct task_struct *p;
-	pid_t *pid_p;
 
 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 		return ERR_PTR(-EINVAL);
@@ -1391,9 +1390,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
 	/* ok, now we should be set up.. */
 
-	/* tast_struct::pid is const pid_t, hence the ugly cast */
-	pid_p = (pid_t*)&(p->pid);
-	*pid_p = pid_nr(pid);
+	CONST_CAST(pid_t, p->pid) = pid_nr(pid);
 	if (clone_flags & CLONE_THREAD) {
 		p->exit_signal = -1;
 		p->group_leader = current->group_leader;
-- 
1.7.1

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