[PATCH] mm: change tlb_finish_mmu() to be more simple

[PATCH] mm: change tlb_finish_mmu() to be more simple

[yalin wang]

This patch remove unneeded *next temp variable,
make this function more simple to read.

Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
---
 mm/memory.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 7f3b9f2..f0040ed 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -270,17 +270,16 @@ void tlb_flush_mmu(struct mmu_gather *tlb)
  */
 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
-	struct mmu_gather_batch *batch, *next;
+	struct mmu_gather_batch *batch;
 
 	tlb_flush_mmu(tlb);
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
 
-	for (batch = tlb->local.next; batch; batch = next) {
-		next = batch->next;
+	for (batch = tlb->local.next; batch; batch = batch->next)
 		free_pages((unsigned long)batch, 0);
-	}
+
 	tlb->local.next = NULL;
 }
 
-- 
1.9.1

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Re: [PATCH] mm: change tlb_finish_mmu() to be more simple

[Kirill A. Shutemov]

On Wed, Nov 04, 2015 at 03:35:31PM +0800, yalin wang wrote:
> This patch remove unneeded *next temp variable,
> make this function more simple to read.
> 
> Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
> ---
>  mm/memory.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 7f3b9f2..f0040ed 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -270,17 +270,16 @@ void tlb_flush_mmu(struct mmu_gather *tlb)
>   */
>  void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
>  {
> -	struct mmu_gather_batch *batch, *next;
> +	struct mmu_gather_batch *batch;
>  
>  	tlb_flush_mmu(tlb);
>  
>  	/* keep the page table cache within bounds */
>  	check_pgt_cache();
>  
> -	for (batch = tlb->local.next; batch; batch = next) {
> -		next = batch->next;
> +	for (batch = tlb->local.next; batch; batch = batch->next)

Use after free? No, thanks.

>  		free_pages((unsigned long)batch, 0);
> -	}
> +
>  	tlb->local.next = NULL;
>  }
>  
> -- 
> 1.9.1
> 
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-- 
 Kirill A. Shutemov

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Re: [PATCH] mm: change tlb_finish_mmu() to be more simple

[Sergey Senozhatsky]

On (11/04/15 15:35), yalin wang wrote:
[..]
>  
> -	for (batch = tlb->local.next; batch; batch = next) {
> -		next = batch->next;
> +	for (batch = tlb->local.next; batch; batch = batch->next)
>  		free_pages((unsigned long)batch, 0);

accessing `batch->next' after calling free_pages() on `batch'?

		-ss

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Re: [PATCH] mm: change tlb_finish_mmu() to be more simple

[yalin wang]

> On Nov 4, 2015, at 16:36, Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> wrote:
> 
> On (11/04/15 15:35), yalin wang wrote:
> [..]
>> 
>> -	for (batch = tlb->local.next; batch; batch = next) {
>> -		next = batch->next;
>> +	for (batch = tlb->local.next; batch; batch = batch->next)
>> 		free_pages((unsigned long)batch, 0);
> 
> accessing `batch->next' after calling free_pages() on `batch'?
> 
> 		-ss
oh,  my mistake, my code is buggy here .

Thanks
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