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Commit 3866ea90 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

ksm: first tidy up madvise_vma() 



madvise.c has several levels of switch statements, what to do in which?
Move MADV_DOFORK code down from madvise_vma() to madvise_behavior(), so
madvise_vma() can be a simple router, to madvise_behavior() by default.

vma->vm_flags is an unsigned long so use the same type for new_flags.  Add
missing comment lines to describe MADV_DONTFORK and MADV_DOFORK.

Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarChris Wright <chrisw@redhat.com>
Signed-off-by: default avatarIzik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 828502d3

mm/madvise.c

+13 −26
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ static long madvise_behavior(struct vm_area_struct * vma, 
	struct mm_struct * mm = vma->vm_mm;

	int error = 0;

	pgoff_t pgoff;

	int new_flags = vma->vm_flags;

	unsigned long new_flags = vma->vm_flags;



	switch (behavior) {

	case MADV_NORMAL:
@@ -57,6 +57,10 @@ static long madvise_behavior(struct vm_area_struct * vma, 
		new_flags |= VM_DONTCOPY;

		break;

	case MADV_DOFORK:

		if (vma->vm_flags & VM_IO) {

			error = -EINVAL;

			goto out;

		}

		new_flags &= ~VM_DONTCOPY;

		break;

	}
@@ -211,37 +215,16 @@ static long 
madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,

		unsigned long start, unsigned long end, int behavior)

{

	long error;



	switch (behavior) {

	case MADV_DOFORK:

		if (vma->vm_flags & VM_IO) {

			error = -EINVAL;

			break;

		}

	case MADV_DONTFORK:

	case MADV_NORMAL:

	case MADV_SEQUENTIAL:

	case MADV_RANDOM:

		error = madvise_behavior(vma, prev, start, end, behavior);

		break;

	case MADV_REMOVE:

		error = madvise_remove(vma, prev, start, end);

		break;



		return madvise_remove(vma, prev, start, end);

	case MADV_WILLNEED:

		error = madvise_willneed(vma, prev, start, end);

		break;



		return madvise_willneed(vma, prev, start, end);

	case MADV_DONTNEED:

		error = madvise_dontneed(vma, prev, start, end);

		break;



		return madvise_dontneed(vma, prev, start, end);

	default:

		BUG();

		break;

		return madvise_behavior(vma, prev, start, end, behavior);

	}

	return error;

}



static int
@@ -262,6 +245,7 @@ madvise_behavior_valid(int behavior) 
		return 0;

	}

}



/*

 * The madvise(2) system call.

 *
@@ -286,6 +270,9 @@ madvise_behavior_valid(int behavior) 
 *		so the kernel can free resources associated with it.

 *  MADV_REMOVE - the application wants to free up the given range of

 *		pages and associated backing store.

 *  MADV_DONTFORK - omit this area from child's address space when forking:

 *		typically, to avoid COWing pages pinned by get_user_pages().

 *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.

 *

 * return values:

 *  zero    - success