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Commit 59b4bf12 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

fs/proc/task_mmu.c: simplify the vma_stop() logic 



m_start() drops ->mmap_sem and does mmput() if it retuns vsyscall
vma. This is because in this case m_stop()->vma_stop() obviously
can't use gate_vma->vm_mm.

Now that we have proc_maps_private->mm we can simplify this logic:

  - Change m_start() to return with ->mmap_sem held unless it returns
    IS_ERR_OR_NULL().

  - Change vma_stop() to use priv->mm and avoid the ugly vma checks,
    this makes "vm_area_struct *vma" unnecessary.

  - This also allows m_start() to use vm_stop().

  - Cleanup m_next() to follow the new locking rule.

    Note: m_stop() looks very ugly, and this temporary uglifies it
    even more. Fixed by the next change.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 29a40ace

fs/proc/task_mmu.c

+19 −16
Original line number Diff line number Diff line
@@ -129,15 +129,14 @@ static void release_task_mempolicy(struct proc_maps_private *priv) 
}

#endif



static void vma_stop(struct proc_maps_private *priv, struct vm_area_struct *vma)

static void vma_stop(struct proc_maps_private *priv)

{

	if (vma && vma != priv->tail_vma) {

		struct mm_struct *mm = vma->vm_mm;

	struct mm_struct *mm = priv->mm;



	release_task_mempolicy(priv);

	up_read(&mm->mmap_sem);

	mmput(mm);

}

}



static void *m_start(struct seq_file *m, loff_t *pos)

{
@@ -199,12 +198,13 @@ static void *m_start(struct seq_file *m, loff_t *pos) 
	if (vma)

		return vma;



	release_task_mempolicy(priv);

	/* End of vmas has been reached */

	m->version = (tail_vma != NULL)? 0: -1UL;

	up_read(&mm->mmap_sem);

	mmput(mm);

	if (tail_vma)

		return tail_vma;



	vma_stop(priv);

	return NULL;

}



static void *m_next(struct seq_file *m, void *v, loff_t *pos)
@@ -212,21 +212,24 @@ static void *m_next(struct seq_file *m, void *v, loff_t *pos) 
	struct proc_maps_private *priv = m->private;

	struct vm_area_struct *vma = v;

	struct vm_area_struct *tail_vma = priv->tail_vma;

	struct vm_area_struct *next;



	(*pos)++;

	if (vma && (vma != tail_vma) && vma->vm_next)

		return vma->vm_next;

	vma_stop(priv, vma);

	return (vma != tail_vma)? tail_vma: NULL;



	next = (vma != tail_vma) ? tail_vma : NULL;

	if (!next)

		vma_stop(priv);

	return next;

}



static void m_stop(struct seq_file *m, void *v)

{

	struct proc_maps_private *priv = m->private;

	struct vm_area_struct *vma = v;



	if (!IS_ERR(vma))

		vma_stop(priv, vma);

	if (!IS_ERR_OR_NULL(v))

		vma_stop(priv);

	if (priv->task)

		put_task_struct(priv->task);

}