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fs/proc/task_mmu.c: shift "priv->task = NULL" from m_start() to m_stop()

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1. There is no reason to reset ->tail_vma in m_start(), if we return
   IS_ERR_OR_NULL() it won't be used.

2. m_start() also clears priv->task to ensure that m_stop() won't use
   the stale pointer if we fail before get_task_struct(). But this is
   ugly and confusing, move this initialization in m_stop().

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>
This commit is contained in:
Oleg Nesterov 2014-10-09 15:25:32 -07:00 committed by Linus Torvalds
parent 23d54837e4
commit 0d5f5f45f9
1 changed files with 3 additions and 6 deletions
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9
fs/proc/task_mmu.c
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@ -146,17 +146,12 @@ static void *m_start(struct seq_file *m, loff_t *pos)
struct vm_area_struct *vma, *tail_vma = NULL;
loff_t l = *pos;
/* Clear the per syscall fields in priv */
priv->task = NULL;
priv->tail_vma = NULL;
/*
* We remember last_addr rather than next_addr to hit with
* vmacache most of the time. We have zero last_addr at
* the beginning and also after lseek. We will have -1 last_addr
* after the end of the vmas.
*/
if (last_addr == -1UL)
return NULL;
@ -228,8 +223,10 @@ static void m_stop(struct seq_file *m, void *v)
if (!IS_ERR_OR_NULL(v))
vma_stop(priv);
if (priv->task)
if (priv->task) {
put_task_struct(priv->task);
priv->task = NULL;
}
}
static int proc_maps_open(struct inode *inode, struct file *file,