Commit 0c255321 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds

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
...@@ -138,12 +138,12 @@ static void vma_stop(struct proc_maps_private *priv) ...@@ -138,12 +138,12 @@ static void vma_stop(struct proc_maps_private *priv)
mmput(mm); 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 proc_maps_private *priv = m->private;
struct mm_struct *mm; struct mm_struct *mm;
struct vm_area_struct *vma, *tail_vma = NULL; struct vm_area_struct *vma;
loff_t l = *pos; unsigned int pos = *ppos;
priv->task = get_pid_task(priv->pid, PIDTYPE_PID); priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
if (!priv->task) if (!priv->task)
...@@ -152,33 +152,19 @@ static void *m_start(struct seq_file *m, loff_t *pos) ...@@ -152,33 +152,19 @@ static void *m_start(struct seq_file *m, loff_t *pos)
mm = priv->mm; mm = priv->mm;
if (!mm || !atomic_inc_not_zero(&mm->mm_users)) if (!mm || !atomic_inc_not_zero(&mm->mm_users))
return NULL; return NULL;
down_read(&mm->mmap_sem);
tail_vma = get_gate_vma(mm); down_read(&mm->mmap_sem);
priv->tail_vma = tail_vma;
hold_task_mempolicy(priv); hold_task_mempolicy(priv);
priv->tail_vma = get_gate_vma(mm);
/* if (pos < mm->map_count) {
* Check the vma index is within the range and do for (vma = mm->mmap; pos; pos--)
* sequential scan until m_index.
*/
vma = NULL;
if ((unsigned long)l < mm->map_count) {
vma = mm->mmap;
while (l-- && vma)
vma = vma->vm_next; vma = vma->vm_next;
goto out;
}
if (l != mm->map_count)
tail_vma = NULL; /* After gate vma */
out:
if (vma)
return vma; return vma;
}
if (tail_vma) if (pos == mm->map_count && priv->tail_vma)
return tail_vma; return priv->tail_vma;
vma_stop(priv); vma_stop(priv);
return NULL; return NULL;
......
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