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Message-ID: <YAjLOWvDblzFICS2@kernel.org>
Date: Thu, 21 Jan 2021 02:30:49 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org,
Jia Zhang <zhang.jia@...ux.alibaba.com>
Subject: Re: [PATCH v2] x86/sgx: Remove redundant if conditions in
sgx_encl_create
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@...ux.alibaba.com>
> > Suggested-by: Sean Christopherson <seanjc@...gle.com>
> > Signed-off-by: Tianjia Zhang <tianjia.zhang@...ux.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
> >
>
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