From: Oleg Nesterov Date: Thu, 9 Oct 2014 22:25:32 +0000 (-0700) Subject: fs/proc/task_mmu.c: shift "priv->task = NULL" from m_start() to m_stop() X-Git-Tag: firefly_0821_release~176^2~3099^2~134 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0d5f5f45f9a4f1f6b694c37f5142ebea893f0a15;p=firefly-linux-kernel-4.4.55.git fs/proc/task_mmu.c: shift "priv->task = NULL" from m_start() to m_stop() 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 Acked-by: Kirill A. Shutemov Acked-by: Cyrill Gorcunov Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index b7e31836a005..30aa2dd3e6f5 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -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,