From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933447AbdACVnx (ORCPT ); Tue, 3 Jan 2017 16:43:53 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:48845 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759355AbdACVnc (ORCPT ); Tue, 3 Jan 2017 16:43:32 -0500 From: Davidlohr Bueso To: mingo@kernel.org, akpm@linux-foundation.org Cc: peterz@infradead.org, torvalds@linux-foundation.org, mark.rutland@arm.com, dave@stgolabs.net, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: [PATCH 1/4] kernel/exit: Compute current directly Date: Tue, 3 Jan 2017 13:43:11 -0800 Message-Id: <1483479794-14013-2-git-send-email-dave@stgolabs.net> X-Mailer: git-send-email 2.6.6 In-Reply-To: <1483479794-14013-1-git-send-email-dave@stgolabs.net> References: <1483479794-14013-1-git-send-email-dave@stgolabs.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 arg. This is also a performance win on some archs such as x86-64 and ppc64 -- arm64 is no longer an issue: https://lkml.org/lkml/2016/12/30/230 Signed-off-by: Davidlohr Bueso --- XXX: do_exit() could further be cleaned up and we'd endup getting rid of tsk for a lot of the exit_*() calls. kernel/exit.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 8f14b866f9f6..2385d434a46e 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -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(); -- 2.6.6