* [PATCH] x86/sgx: Remove redundant if conditions in sgx_encl_create
@ 2021-01-18 13:33 Tianjia Zhang
2021-01-19 20:29 ` Sean Christopherson
2021-01-20 14:39 ` Jarkko Sakkinen
0 siblings, 2 replies; 3+ messages in thread
From: Tianjia Zhang @ 2021-01-18 13:33 UTC (permalink / raw)
To: Jarkko Sakkinen, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, Andrew Morton, Shuah Khan, haitao.huang,
Kai Huang, x86, linux-sgx, linux-kernel, linux-mm,
linux-kselftest, Jia Zhang
Cc: Tianjia Zhang
In this scenario, there is no case where va_page is NULL, and
the error has been checked. The if condition statement here is
redundant, so remove the condition detection.
Reported-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
---
arch/x86/kernel/cpu/sgx/ioctl.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 90a5caf76939..f45957c05f69 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -66,9 +66,8 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
va_page = sgx_encl_grow(encl);
if (IS_ERR(va_page))
return PTR_ERR(va_page);
- else if (va_page)
- list_add(&va_page->list, &encl->va_pages);
- /* else the tail page of the VA page list had free slots. */
+
+ list_add(&va_page->list, &encl->va_pages);
/* The extra page goes to SECS. */
encl_size = secs->size + PAGE_SIZE;
--
2.19.1.3.ge56e4f7
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/sgx: Remove redundant if conditions in sgx_encl_create
2021-01-18 13:33 [PATCH] x86/sgx: Remove redundant if conditions in sgx_encl_create Tianjia Zhang
@ 2021-01-19 20:29 ` Sean Christopherson
2021-01-20 14:39 ` Jarkko Sakkinen
1 sibling, 0 replies; 3+ messages in thread
From: Sean Christopherson @ 2021-01-19 20:29 UTC (permalink / raw)
To: Tianjia Zhang
Cc: Jarkko Sakkinen, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, Andrew Morton, Shuah Khan, haitao.huang,
Kai Huang, x86, linux-sgx, linux-kernel, linux-mm,
linux-kselftest, Jia Zhang
On Mon, Jan 18, 2021, Tianjia Zhang wrote:
> In this scenario, there is no case where va_page is NULL, and
> the error has been checked. The if condition statement here is
> redundant, so remove the condition detection.
>
> Reported-by: Jia Zhang <zhang.jia@linux.alibaba.com>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
> arch/x86/kernel/cpu/sgx/ioctl.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index 90a5caf76939..f45957c05f69 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -66,9 +66,8 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
> va_page = sgx_encl_grow(encl);
> if (IS_ERR(va_page))
> return PTR_ERR(va_page);
> - else if (va_page)
> - list_add(&va_page->list, &encl->va_pages);
> - /* else the tail page of the VA page list had free slots. */
> +
> + list_add(&va_page->list, &encl->va_pages);
Maybe add a WARN_ONCE to document/enforce the behavior?
va_page = sgx_encl_grow(encl);
if (IS_ERR(va_page))
return PTR_ERR(va_page);
if (WARN_ONCE(!va_page, "clever comment goes here))
return -EIO;
list_add(&va_page->list, &encl->va_pages);
>
> /* The extra page goes to SECS. */
> encl_size = secs->size + PAGE_SIZE;
> --
> 2.19.1.3.ge56e4f7
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/sgx: Remove redundant if conditions in sgx_encl_create
2021-01-18 13:33 [PATCH] x86/sgx: Remove redundant if conditions in sgx_encl_create Tianjia Zhang
2021-01-19 20:29 ` Sean Christopherson
@ 2021-01-20 14:39 ` Jarkko Sakkinen
1 sibling, 0 replies; 3+ messages in thread
From: Jarkko Sakkinen @ 2021-01-20 14:39 UTC (permalink / raw)
To: Tianjia Zhang
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, H. Peter Anvin,
Andrew Morton, Shuah Khan, haitao.huang, Kai Huang, x86,
linux-sgx, linux-kernel, linux-mm, linux-kselftest, Jia Zhang
On Mon, Jan 18, 2021 at 09:33:58PM +0800, Tianjia Zhang wrote:
> In this scenario, there is no case where va_page is NULL, and
> the error has been checked. The if condition statement here is
> redundant, so remove the condition detection.
>
> Reported-by: Jia Zhang <zhang.jia@linux.alibaba.com>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
What do we gain with this change and why is it reported as a
regression?
/Jarkko
> ---
> arch/x86/kernel/cpu/sgx/ioctl.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index 90a5caf76939..f45957c05f69 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -66,9 +66,8 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
> va_page = sgx_encl_grow(encl);
> if (IS_ERR(va_page))
> return PTR_ERR(va_page);
> - else if (va_page)
> - list_add(&va_page->list, &encl->va_pages);
> - /* else the tail page of the VA page list had free slots. */
> +
> + list_add(&va_page->list, &encl->va_pages);
>
> /* The extra page goes to SECS. */
> encl_size = secs->size + PAGE_SIZE;
> --
> 2.19.1.3.ge56e4f7
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-20 14:47 UTC | newest]
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2021-01-18 13:33 [PATCH] x86/sgx: Remove redundant if conditions in sgx_encl_create Tianjia Zhang
2021-01-19 20:29 ` Sean Christopherson
2021-01-20 14:39 ` Jarkko Sakkinen
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