diff options
| author | Dominik Brodowski <linux@dominikbrodowski.net> | 2018-03-11 11:34:26 +0100 |
|---|---|---|
| committer | Dominik Brodowski <linux@dominikbrodowski.net> | 2018-04-02 20:15:02 +0200 |
| commit | 2de0db992de189fccc83fed57c30875144821491 (patch) | |
| tree | 138ea29f99e5e5ebb4c304da1961cdf0731a8b36 | |
| parent | 6b27aef09fea32b805a8c81287b1bb80362dadb0 (diff) | |
mm: use do_futex() instead of sys_futex() in mm_release()
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
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
| -rw-r--r-- | include/linux/futex.h | 13 | ||||
| -rw-r--r-- | kernel/fork.c | 4 |
2 files changed, 12 insertions, 5 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h index c0fb9a24bbd2..821ae502d3d8 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -9,9 +9,6 @@ struct inode; struct mm_struct; struct task_struct; -long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, - u32 __user *uaddr2, u32 val2, u32 val3); - extern int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi); @@ -55,6 +52,9 @@ union futex_key { #ifdef CONFIG_FUTEX extern void exit_robust_list(struct task_struct *curr); + +long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, + u32 __user *uaddr2, u32 val2, u32 val3); #ifdef CONFIG_HAVE_FUTEX_CMPXCHG #define futex_cmpxchg_enabled 1 #else @@ -64,6 +64,13 @@ extern int futex_cmpxchg_enabled; static inline void exit_robust_list(struct task_struct *curr) { } + +static inline long do_futex(u32 __user *uaddr, int op, u32 val, + ktime_t *timeout, u32 __user *uaddr2, + u32 val2, u32 val3) +{ + return -EINVAL; +} #endif #ifdef CONFIG_FUTEX_PI 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; } |