linux-kernel - Re: [PATCH v4 05/17] arm64: hibernate: remove gotos in create_safe_exec

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Date:   Tue, 10 Sep 2019 10:12:54 +0100
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     Matthias Brugger <mbrugger@...e.com>
Cc:     James Morris <jmorris@...ei.org>, Sasha Levin <sashal@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        kexec mailing list <kexec@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>, will@...nel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Marc Zyngier <marc.zyngier@....com>,
        James Morse <james.morse@....com>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Bhupesh Sharma <bhsharma@...hat.com>,
        linux-mm <linux-mm@...ck.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v4 05/17] arm64: hibernate: remove gotos in create_safe_exec_page

> On 09/09/2019 20:12, Pavel Tatashin wrote:
> > Usually, gotos are used to handle cleanup after exception, but
> > in case of create_safe_exec_page there are no clean-ups. So,
> > simply return the errors directly.
> >
>
> While at it, how about also cleaning up swsusp_arch_resume() which has the same
> issue.

Thank you for suggestion. I will do cleanups in swsusp_arch_resume() as well.

Pasha

>
> Regards,
> Matthias
>
> > Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
> > Reviewed-by: James Morse <james.morse@....com>
> > ---
> >  arch/arm64/kernel/hibernate.c | 34 +++++++++++-----------------------
> >  1 file changed, 11 insertions(+), 23 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
> > index 47a861e0cb0c..7bbeb33c700d 100644
> > --- a/arch/arm64/kernel/hibernate.c
> > +++ b/arch/arm64/kernel/hibernate.c
> > @@ -198,7 +198,6 @@ static int create_safe_exec_page(void *src_start, size_t length,
> >                                unsigned long dst_addr,
> >                                phys_addr_t *phys_dst_addr)
> >  {
> > -     int rc = 0;
> >       pgd_t *trans_pgd;
> >       pgd_t *pgdp;
> >       pud_t *pudp;
> > @@ -206,47 +205,37 @@ static int create_safe_exec_page(void *src_start, size_t length,
> >       pte_t *ptep;
> >       unsigned long dst = get_safe_page(GFP_ATOMIC);
> >
> > -     if (!dst) {
> > -             rc = -ENOMEM;
> > -             goto out;
> > -     }
> > +     if (!dst)
> > +             return -ENOMEM;
> >
> >       memcpy((void *)dst, src_start, length);
> >       __flush_icache_range(dst, dst + length);
> >
> >       trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
> > -     if (!trans_pgd) {
> > -             rc = -ENOMEM;
> > -             goto out;
> > -     }
> > +     if (!trans_pgd)
> > +             return -ENOMEM;
> >
> >       pgdp = pgd_offset_raw(trans_pgd, dst_addr);
> >       if (pgd_none(READ_ONCE(*pgdp))) {
> >               pudp = (void *)get_safe_page(GFP_ATOMIC);
> > -             if (!pudp) {
> > -                     rc = -ENOMEM;
> > -                     goto out;
> > -             }
> > +             if (!pudp)
> > +                     return -ENOMEM;
> >               pgd_populate(&init_mm, pgdp, pudp);
> >       }
> >
> >       pudp = pud_offset(pgdp, dst_addr);
> >       if (pud_none(READ_ONCE(*pudp))) {
> >               pmdp = (void *)get_safe_page(GFP_ATOMIC);
> > -             if (!pmdp) {
> > -                     rc = -ENOMEM;
> > -                     goto out;
> > -             }
> > +             if (!pmdp)
> > +                     return -ENOMEM;
> >               pud_populate(&init_mm, pudp, pmdp);
> >       }
> >
> >       pmdp = pmd_offset(pudp, dst_addr);
> >       if (pmd_none(READ_ONCE(*pmdp))) {
> >               ptep = (void *)get_safe_page(GFP_ATOMIC);
> > -             if (!ptep) {
> > -                     rc = -ENOMEM;
> > -                     goto out;
> > -             }
> > +             if (!ptep)
> > +                     return -ENOMEM;
> >               pmd_populate_kernel(&init_mm, pmdp, ptep);
> >       }
> >
> > @@ -272,8 +261,7 @@ static int create_safe_exec_page(void *src_start, size_t length,
> >
> >       *phys_dst_addr = virt_to_phys((void *)dst);
> >
> > -out:
> > -     return rc;
> > +     return 0;
> >  }
> >
> >  #define dcache_clean_range(start, end)       __flush_dcache_area(start, (end - start))
> >