* [PATCH] mm, mempolicy: Check parameters first in kernel_get_mempolicy
@ 2020-08-01 9:08 Wenchao Hao
2020-08-04 3:25 ` Andrew Morton
0 siblings, 1 reply; 2+ messages in thread
From: Wenchao Hao @ 2020-08-01 9:08 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, Wenchao Hao
Previous implement called untagged_addr before error check, while
if the error check failed and return EINVAL, the untagged_addr is
just useless work.
Signed-off-by: Wenchao Hao <haowenchao22@gmail.com>
---
mm/mempolicy.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 381320671677..dac0cd0df3e1 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1632,11 +1632,11 @@ static int kernel_get_mempolicy(int __user *policy,
int uninitialized_var(pval);
nodemask_t nodes;
- addr = untagged_addr(addr);
-
if (nmask != NULL && maxnode < nr_node_ids)
return -EINVAL;
+ addr = untagged_addr(addr);
+
err = do_get_mempolicy(&pval, &nodes, addr, flags);
if (err)
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] mm, mempolicy: Check parameters first in kernel_get_mempolicy
2020-08-01 9:08 [PATCH] mm, mempolicy: Check parameters first in kernel_get_mempolicy Wenchao Hao
@ 2020-08-04 3:25 ` Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2020-08-04 3:25 UTC (permalink / raw)
To: Wenchao Hao; +Cc: linux-mm, linux-kernel
On Sat, 1 Aug 2020 17:08:26 +0800 Wenchao Hao <haowenchao22@gmail.com> wrote:
> Previous implement called untagged_addr before error check, while
> if the error check failed and return EINVAL, the untagged_addr is
> just useless work.
>
> ...
>
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1632,11 +1632,11 @@ static int kernel_get_mempolicy(int __user *policy,
> int uninitialized_var(pval);
> nodemask_t nodes;
>
> - addr = untagged_addr(addr);
> -
> if (nmask != NULL && maxnode < nr_node_ids)
> return -EINVAL;
>
> + addr = untagged_addr(addr);
> +
> err = do_get_mempolicy(&pval, &nodes, addr, flags);
>
> if (err)
Well, the compiler will surely avoid that useless work. But the code
is better this way.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-08-01 9:08 [PATCH] mm, mempolicy: Check parameters first in kernel_get_mempolicy Wenchao Hao
2020-08-04 3:25 ` Andrew Morton
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