diff mbox series

x86/sgx: Remove redundant if conditions in sgx_encl_create

Message ID 20210118133358.99311-1-tianjia.zhang@linux.alibaba.com (mailing list archive)
State New, archived
Headers show
Series x86/sgx: Remove redundant if conditions in sgx_encl_create | expand

Commit Message

Tianjia Zhang Jan. 18, 2021, 1:33 p.m. UTC
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(-)

Comments

Sean Christopherson Jan. 19, 2021, 8:29 p.m. UTC | #1
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
>
Jarkko Sakkinen Jan. 20, 2021, 2:39 p.m. UTC | #2
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
> 
>
diff mbox series

Patch

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;