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: Oleg Nesterov <oleg@redhat.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -129,14 +129,13 @@ static void release_task_mempolicy(struct proc_maps_private *priv)
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}
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#endif
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static void vma_stop(struct proc_maps_private *priv, struct vm_area_struct *vma)
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static void vma_stop(struct proc_maps_private *priv)
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{
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if (vma && vma != priv->tail_vma) {
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struct mm_struct *mm = vma->vm_mm;
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release_task_mempolicy(priv);
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up_read(&mm->mmap_sem);
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mmput(mm);
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}
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struct mm_struct *mm = priv->mm;
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release_task_mempolicy(priv);
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up_read(&mm->mmap_sem);
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mmput(mm);
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}
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static void *m_start(struct seq_file *m, loff_t *pos)
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@ -199,12 +198,13 @@ out:
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if (vma)
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return vma;
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release_task_mempolicy(priv);
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/* End of vmas has been reached */
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m->version = (tail_vma != NULL)? 0: -1UL;
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up_read(&mm->mmap_sem);
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mmput(mm);
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return tail_vma;
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if (tail_vma)
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return tail_vma;
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vma_stop(priv);
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return NULL;
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}
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static void *m_next(struct seq_file *m, void *v, loff_t *pos)
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@ -212,21 +212,24 @@ static void *m_next(struct seq_file *m, void *v, loff_t *pos)
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struct proc_maps_private *priv = m->private;
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struct vm_area_struct *vma = v;
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struct vm_area_struct *tail_vma = priv->tail_vma;
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struct vm_area_struct *next;
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(*pos)++;
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if (vma && (vma != tail_vma) && vma->vm_next)
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return vma->vm_next;
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vma_stop(priv, vma);
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return (vma != tail_vma)? tail_vma: NULL;
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next = (vma != tail_vma) ? tail_vma : NULL;
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if (!next)
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vma_stop(priv);
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return next;
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}
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static void m_stop(struct seq_file *m, void *v)
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{
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struct proc_maps_private *priv = m->private;
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struct vm_area_struct *vma = v;
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if (!IS_ERR(vma))
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vma_stop(priv, vma);
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if (!IS_ERR_OR_NULL(v))
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vma_stop(priv);
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if (priv->task)
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put_task_struct(priv->task);
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}
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