Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0039962a authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Ingo Molnar
Browse files

kernel/exit: Compute 'current' directly 



This patch effectively replaces the tsk pointer dereference (which is
obviously == current), to directly use get_current() macro. In this
case, do_exit() always passes current to exit_mm(), hence we can
simply get rid of the argument. This is also a performance win on some
archs such as x86-64 and ppc64 -- arm64 is no longer an issue.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: mark.rutland@arm.com
Link: http://lkml.kernel.org/r/1483479794-14013-2-git-send-email-dave@stgolabs.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent aef591cd

kernel/exit.c

+11 −11
Original line number Diff line number Diff line
@@ -468,12 +468,12 @@ void mm_update_next_owner(struct mm_struct *mm) 
 * Turn us into a lazy TLB process if we

 * aren't already..

 */

static void exit_mm(struct task_struct *tsk)

static void exit_mm(void)

{

	struct mm_struct *mm = tsk->mm;

	struct mm_struct *mm = current->mm;

	struct core_state *core_state;



	mm_release(tsk, mm);

	mm_release(current, mm);

	if (!mm)

		return;

	sync_mm_rss(mm);
@@ -491,7 +491,7 @@ static void exit_mm(struct task_struct *tsk) 


		up_read(&mm->mmap_sem);



		self.task = tsk;

		self.task = current;

		self.next = xchg(&core_state->dumper.next, &self);

		/*

		 * Implies mb(), the result of xchg() must be visible
@@ -501,22 +501,22 @@ static void exit_mm(struct task_struct *tsk) 
			complete(&core_state->startup);



		for (;;) {

			set_task_state(tsk, TASK_UNINTERRUPTIBLE);

			set_task_state(current, TASK_UNINTERRUPTIBLE);

			if (!self.task) /* see coredump_finish() */

				break;

			freezable_schedule();

		}

		__set_task_state(tsk, TASK_RUNNING);

		__set_task_state(current, TASK_RUNNING);

		down_read(&mm->mmap_sem);

	}

	atomic_inc(&mm->mm_count);

	BUG_ON(mm != tsk->active_mm);

	BUG_ON(mm != current->active_mm);

	/* more a memory barrier than a real lock */

	task_lock(tsk);

	tsk->mm = NULL;

	task_lock(current);

	current->mm = NULL;

	up_read(&mm->mmap_sem);

	enter_lazy_tlb(mm, current);

	task_unlock(tsk);

	task_unlock(current);

	mm_update_next_owner(mm);

	mmput(mm);

	if (test_thread_flag(TIF_MEMDIE))
@@ -823,7 +823,7 @@ void __noreturn do_exit(long code) 
	tsk->exit_code = code;

	taskstats_exit(tsk, group_dead);



	exit_mm(tsk);

	exit_mm();



	if (group_dead)

		acct_process();