diff options
| author | Ingo Molnar | 2017-02-02 12:32:21 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2017-03-03 01:43:40 +0100 |
| commit | d026ce796cbca3c49678a68bb4a39fb4b9cf8192 (patch) | |
| tree | f59d22d27480adc95d6d14d826346c791a045188 /include/linux/sched | |
| parent | abe722a1c59728c6c0ea4e4d5efcfe397c8abebc (diff) | |
sched/headers: Move in_vfork() from <linux/sched.h> to <linux/sched/mm.h>
The in_vfork() function deals with task->mm, so it better belongs
into <linux/sched/mm.h>.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/sched')
| -rw-r--r-- | include/linux/sched/mm.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 93fad9f0f466..64d83fa8d93a 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -121,4 +121,30 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, static inline void arch_pick_mmap_layout(struct mm_struct *mm) {} #endif +static inline bool in_vfork(struct task_struct *tsk) +{ + bool ret; + + /* + * need RCU to access ->real_parent if CLONE_VM was used along with + * CLONE_PARENT. + * + * We check real_parent->mm == tsk->mm because CLONE_VFORK does not + * imply CLONE_VM + * + * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus + * ->real_parent is not necessarily the task doing vfork(), so in + * theory we can't rely on task_lock() if we want to dereference it. + * + * And in this case we can't trust the real_parent->mm == tsk->mm + * check, it can be false negative. But we do not care, if init or + * another oom-unkillable task does this it should blame itself. + */ + rcu_read_lock(); + ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm; + rcu_read_unlock(); + + return ret; +} + #endif /* _LINUX_SCHED_MM_H */ |