1/* Copyright (C) 2009 Red Hat, Inc. 2 * 3 * See ../COPYING for licensing terms. 4 */ 5 6#include <linux/mm.h> 7#include <linux/mmu_context.h> 8#include <linux/module.h> 9#include <linux/sched.h> 10 11#include <asm/mmu_context.h> 12 13/* 14 * use_mm 15 * Makes the calling kernel thread take on the specified 16 * mm context. 17 * Called by the retry thread execute retries within the 18 * iocb issuer's mm context, so that copy_from/to_user 19 * operations work seamlessly for aio. 20 * (Note: this routine is intended to be called only 21 * from a kernel thread context) 22 */ 23void use_mm(struct mm_struct *mm) 24{ 25 struct mm_struct *active_mm; 26 struct task_struct *tsk = current; 27 28 task_lock(tsk); 29 active_mm = tsk->active_mm; 30 if (active_mm != mm) { 31 atomic_inc(&mm->mm_count); 32 tsk->active_mm = mm; 33 } 34 tsk->mm = mm; 35 switch_mm(active_mm, mm, tsk); 36 task_unlock(tsk); 37 38 if (active_mm != mm) 39 mmdrop(active_mm); 40} 41EXPORT_SYMBOL_GPL(use_mm); 42 43/* 44 * unuse_mm 45 * Reverses the effect of use_mm, i.e. releases the 46 * specified mm context which was earlier taken on 47 * by the calling kernel thread 48 * (Note: this routine is intended to be called only 49 * from a kernel thread context) 50 */ 51void unuse_mm(struct mm_struct *mm) 52{ 53 struct task_struct *tsk = current; 54 55 task_lock(tsk); 56 sync_mm_rss(tsk, mm); 57 tsk->mm = NULL; 58 /* active_mm is still 'mm' */ 59 enter_lazy_tlb(mm, tsk); 60 task_unlock(tsk); 61} 62EXPORT_SYMBOL_GPL(unuse_mm); 63