vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- fs/aio.c | 47 +---------------------------------- include/linux/mmu_context.h | 9 ++++++ mm/Makefile | 2 +- mm/mmu_context.c | 58 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 69 insertions(+), 47 deletions(-) create mode 100644 include/linux/mmu_context.h create mode 100644 mm/mmu_context.c diff --git a/fs/aio.c b/fs/aio.c index d065b2c..fc21c23 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -24,6 +24,7 @@ #include <linux/file.h> #include <linux/mm.h> #include <linux/mman.h> +#include <linux/mmu_context.h> #include <linux/slab.h> #include <linux/timer.h> #include <linux/aio.h> @@ -34,7 +35,6 @@ #include <asm/kmap_types.h> #include <asm/uaccess.h> -#include <asm/mmu_context.h> #if DEBUG > 1 #define dprintk printk @@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) } /* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * Called by the retry thread execute retries within the - * iocb issuer's mm context, so that copy_from/to_user - * operations work seamlessly for aio. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->active_mm; - atomic_inc(&mm->mm_count); - tsk->mm = mm; - tsk->active_mm = mm; - switch_mm(active_mm, mm, tsk); - task_unlock(tsk); - - mmdrop(active_mm); -} - -/* - * unuse_mm - * Reverses the effect of use_mm, i.e. releases the - * specified mm context which was earlier taken on - * by the calling kernel thread - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -static void unuse_mm(struct mm_struct *mm) -{ - struct task_struct *tsk = current; - - task_lock(tsk); - tsk->mm = NULL; - /* active_mm is still 'mm' */ - enter_lazy_tlb(mm, tsk); - task_unlock(tsk); -} - -/* * Queue up a kiocb to be retried. Assumes that the kiocb * has already been marked as kicked, and places it on * the retry run list for the corresponding ioctx, if it diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h new file mode 100644 index 0000000..70fffeb --- /dev/null +++ b/include/linux/mmu_context.h @@ -0,0 +1,9 @@ +#ifndef _LINUX_MMU_CONTEXT_H +#define _LINUX_MMU_CONTEXT_H + +struct mm_struct; + +void use_mm(struct mm_struct *mm); +void unuse_mm(struct mm_struct *mm); + +#endif diff --git a/mm/Makefile b/mm/Makefile index 5e0bd64..46c3892 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -11,7 +11,7 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \ maccess.o page_alloc.o page-writeback.o pdflush.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \ - page_isolation.o mm_init.o $(mmu-y) + page_isolation.o mm_init.o mmu_context.o $(mmu-y) obj-y += init-mm.o obj-$(CONFIG_PROC_PAGE_MONITOR) += pagewalk.o diff --git a/mm/mmu_context.c b/mm/mmu_context.c new file mode 100644 index 0000000..9989c2f --- /dev/null +++ b/mm/mmu_context.c @@ -0,0 +1,58 @@ +/* Copyright (C) 2009 Red Hat, Inc. + * + * See ../COPYING for licensing terms. + */ + +#include <linux/mm.h> +#include <linux/mmu_context.h> +#include <linux/module.h> +#include <linux/sched.h> + +#include <asm/mmu_context.h> + +/* + * use_mm + * Makes the calling kernel thread take on the specified + * mm context. + * Called by the retry thread execute retries within the + * iocb issuer's mm context, so that copy_from/to_user + * operations work seamlessly for aio. + * (Note: this routine is intended to be called only + * from a kernel thread context) + */ +void use_mm(struct mm_struct *mm) +{ + struct mm_struct *active_mm; + struct task_struct *tsk = current; + + task_lock(tsk); + active_mm = tsk->active_mm; + atomic_inc(&mm->mm_count); + tsk->mm = mm; + tsk->active_mm = mm; + switch_mm(active_mm, mm, tsk); + task_unlock(tsk); + + mmdrop(active_mm); +} +EXPORT_SYMBOL_GPL(use_mm); + +/* + * unuse_mm + * Reverses the effect of use_mm, i.e. releases the + * specified mm context which was earlier taken on + * by the calling kernel thread + * (Note: this routine is intended to be called only + * from a kernel thread context) + */ +void unuse_mm(struct mm_struct *mm) +{ + struct task_struct *tsk = current; + + task_lock(tsk); + tsk->mm = NULL; + /* active_mm is still 'mm' */ + enter_lazy_tlb(mm, tsk); + task_unlock(tsk); +} +EXPORT_SYMBOL_GPL(unuse_mm); -- 1.6.2.5 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization