linux-kernel - [RFC PATCH 03/35] syscalls: mm_release(): use do_futex() instead of sys

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Message-Id: <20180311105557.20807-4-linux@dominikbrodowski.net>
Date:   Sun, 11 Mar 2018 11:55:25 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, luto@...nel.org,
        torvalds@...ux-foundation.org, mingo@...nel.org,
        viro@...iv.linux.org.uk, akpm@...ux-foundation.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Darren Hart <dvhart@...radead.org>
Subject: [RFC PATCH 03/35] syscalls: mm_release(): use do_futex() instead of sys_futex()

sys_futex() is a wrapper to do_futex() which does not modify any
values here:

- uaddr, val and val3 are kept the same

- op is masked with FUTEX_CMD_MASK, but is always set to FUTEX_WAKE.
  Therefore, val2 is always 0.

- as utime is set to NULL, *timeout is NULL

CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: Peter Zijlstra <peterz@...radead.org>
CC: Darren Hart <dvhart@...radead.org>
CC: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 kernel/fork.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index e5d9d405ae4e..b1e031aac9db 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1198,8 +1198,8 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 			 * not set up a proper pointer then tough luck.
 			 */
 			put_user(0, tsk->clear_child_tid);
-			sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
-					1, NULL, NULL, 0);
+			do_futex(tsk->clear_child_tid, FUTEX_WAKE,
+					1, NULL, NULL, 0, 0);
 		}
 		tsk->clear_child_tid = NULL;
 	}
-- 
2.16.2