[PATCH] mm: uml pte atomicity

There's usually a good reason when a pte is examined without the lock; but it
makes me nervous when the pointer is dereferenced more than once.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/arch/um/kernel/process_kern.c b/arch/um/kernel/process_kern.c
index 0d73ceeece72..34b54a3e2132 100644
--- a/arch/um/kernel/process_kern.c
+++ b/arch/um/kernel/process_kern.c
@@ -222,6 +222,7 @@ void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
         pud_t *pud;
         pmd_t *pmd;
         pte_t *pte;
+        pte_t ptent;
 
         if(task->mm == NULL) 
                 return(ERR_PTR(-EINVAL));
@@ -238,12 +239,13 @@ void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
                 return(ERR_PTR(-EINVAL));
 
         pte = pte_offset_kernel(pmd, addr);
-        if(!pte_present(*pte)) 
+        ptent = *pte;
+        if(!pte_present(ptent))
                 return(ERR_PTR(-EINVAL));
 
         if(pte_out != NULL)
-                *pte_out = *pte;
-        return((void *) (pte_val(*pte) & PAGE_MASK) + (addr & ~PAGE_MASK));
+                *pte_out = ptent;
+        return((void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK));
 }
 
 char *current_cmd(void)