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Commit 0c255321 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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fs/proc/task_mmu.c: simplify m_start() to make it readable 



Now that m->version is gone we can cleanup m_start(). In particular,

  - Remove the "unsigned long" typecast, m->index can't be negative
    or exceed ->map_count. But lets use "unsigned int pos" to make
    it clear that "pos < map_count" is safe.

  - Remove the unnecessary "vma != NULL" check in the main loop. It
    can't be NULL unless we have a vm bug.

  - This also means that "pos < map_count" case can simply return the
    valid vma and avoid "goto" and subsequent checks.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Cyrill 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 ebb6cdde

fs/proc/task_mmu.c

+10 −24
Original line number Diff line number Diff line
@@ -138,12 +138,12 @@ static void vma_stop(struct proc_maps_private *priv) 
	mmput(mm);

}



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

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

{

	struct proc_maps_private *priv = m->private;

	struct mm_struct *mm;

	struct vm_area_struct *vma, *tail_vma = NULL;

	loff_t l = *pos;

	struct vm_area_struct *vma;

	unsigned int pos = *ppos;



	priv->task = get_pid_task(priv->pid, PIDTYPE_PID);

	if (!priv->task)
@@ -152,33 +152,19 @@ static void *m_start(struct seq_file *m, loff_t *pos) 
	mm = priv->mm;

	if (!mm || !atomic_inc_not_zero(&mm->mm_users))

		return NULL;

	down_read(&mm->mmap_sem);



	tail_vma = get_gate_vma(mm);

	priv->tail_vma = tail_vma;

	down_read(&mm->mmap_sem);

	hold_task_mempolicy(priv);

	priv->tail_vma = get_gate_vma(mm);



	/*

	 * Check the vma index is within the range and do

	 * sequential scan until m_index.

	 */

	vma = NULL;

	if ((unsigned long)l < mm->map_count) {

		vma = mm->mmap;

		while (l-- && vma)

	if (pos < mm->map_count) {

		for (vma = mm->mmap; pos; pos--)

			vma = vma->vm_next;

		goto out;

	}



	if (l != mm->map_count)

		tail_vma = NULL; /* After gate vma */



out:

	if (vma)

		return vma;

	}



	if (tail_vma)

		return tail_vma;

	if (pos == mm->map_count && priv->tail_vma)

		return priv->tail_vma;



	vma_stop(priv);

	return NULL;