* [PATCH v2] x86/sgx: Remove redundant if conditions in sgx_encl_create
@ 2021-01-20 3:53 Tianjia Zhang
2021-01-20 17:47 ` Sean Christopherson
0 siblings, 1 reply; 4+ messages in thread
From: Tianjia Zhang @ 2021-01-20 3:53 UTC (permalink / raw)
To: Jarkko Sakkinen, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, Sean Christopherson, x86, linux-sgx,
linux-kernel, 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>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
---
arch/x86/kernel/cpu/sgx/ioctl.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 1c6ecf9fbeff..efad2fb61c76 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -66,9 +66,12 @@ 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. */
+
+ if (WARN_ONCE(!va_page,
+ "the tail page of the VA page list had free slots\n"))
+ 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 related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] x86/sgx: Remove redundant if conditions in sgx_encl_create
2021-01-20 3:53 [PATCH v2] x86/sgx: Remove redundant if conditions in sgx_encl_create Tianjia Zhang
@ 2021-01-20 17:47 ` Sean Christopherson
2021-01-21 0:30 ` Jarkko Sakkinen
2021-01-24 6:33 ` Tianjia Zhang
0 siblings, 2 replies; 4+ messages in thread
From: Sean Christopherson @ 2021-01-20 17:47 UTC (permalink / raw)
To: Tianjia Zhang
Cc: Jarkko Sakkinen, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, x86, linux-sgx, linux-kernel, Jia Zhang
On Wed, Jan 20, 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>
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
> arch/x86/kernel/cpu/sgx/ioctl.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index 1c6ecf9fbeff..efad2fb61c76 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -66,9 +66,12 @@ 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. */
> +
> + if (WARN_ONCE(!va_page,
> + "the tail page of the VA page list had free slots\n"))
IMO it's worth trimming down the message to keep this on a single line. The
newline isn't necessary, and this code expects a completely empty list, e.g. it
can be reworded to something like:
if (WARN_ONCE(!va_page, "non-empty VA page list before ECREATE"))
> + 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] 4+ messages in thread
* Re: [PATCH v2] x86/sgx: Remove redundant if conditions in sgx_encl_create
2021-01-20 17:47 ` Sean Christopherson
@ 2021-01-21 0:30 ` Jarkko Sakkinen
2021-01-24 6:33 ` Tianjia Zhang
1 sibling, 0 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2021-01-21 0:30 UTC (permalink / raw)
To: Sean Christopherson
Cc: Tianjia Zhang, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, x86, linux-sgx, linux-kernel, Jia Zhang
On Wed, Jan 20, 2021 at 09:47:53AM -0800, Sean Christopherson wrote:
> On Wed, Jan 20, 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>
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> > ---
> > arch/x86/kernel/cpu/sgx/ioctl.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> > index 1c6ecf9fbeff..efad2fb61c76 100644
> > --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> > @@ -66,9 +66,12 @@ 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. */
> > +
> > + if (WARN_ONCE(!va_page,
> > + "the tail page of the VA page list had free slots\n"))
>
> IMO it's worth trimming down the message to keep this on a single line. The
> newline isn't necessary, and this code expects a completely empty list, e.g. it
> can be reworded to something like:
>
> if (WARN_ONCE(!va_page, "non-empty VA page list before ECREATE"))
Agreed. If I recall correctly, these days you can have at least 100
characters per line (if not more, cannot recall the exact number).
/Jarkko
>
> > + 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] 4+ messages in thread
* Re: [PATCH v2] x86/sgx: Remove redundant if conditions in sgx_encl_create
2021-01-20 17:47 ` Sean Christopherson
2021-01-21 0:30 ` Jarkko Sakkinen
@ 2021-01-24 6:33 ` Tianjia Zhang
1 sibling, 0 replies; 4+ messages in thread
From: Tianjia Zhang @ 2021-01-24 6:33 UTC (permalink / raw)
To: Sean Christopherson
Cc: Jarkko Sakkinen, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, x86, linux-sgx, linux-kernel, Jia Zhang
On 1/21/21 1:47 AM, Sean Christopherson wrote:
> On Wed, Jan 20, 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>
>> Suggested-by: Sean Christopherson <seanjc@google.com>
>> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
>> ---
>> arch/x86/kernel/cpu/sgx/ioctl.c | 9 ++++++---
>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
>> index 1c6ecf9fbeff..efad2fb61c76 100644
>> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
>> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
>> @@ -66,9 +66,12 @@ 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. */
>> +
>> + if (WARN_ONCE(!va_page,
>> + "the tail page of the VA page list had free slots\n"))
>
> IMO it's worth trimming down the message to keep this on a single line. The
> newline isn't necessary, and this code expects a completely empty list, e.g. it
> can be reworded to something like:
>
> if (WARN_ONCE(!va_page, "non-empty VA page list before ECREATE"))
>
Thanks for your suggestion, I have resubmitted a set of patches.
Best regards,
Tianjia
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-01-20 3:53 [PATCH v2] x86/sgx: Remove redundant if conditions in sgx_encl_create Tianjia Zhang
2021-01-20 17:47 ` Sean Christopherson
2021-01-21 0:30 ` Jarkko Sakkinen
2021-01-24 6:33 ` Tianjia Zhang
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