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Message-ID: <CAJ6HWG7kvWtZHTBMiFAQriUn84E8SYuGmtAGmW8YVwqUyoUYgQ@mail.gmail.com>
Date: Wed, 2 Aug 2023 17:00:18 -0300
From: Leonardo Bras Soares Passos <leobras@...hat.com>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: Will Deacon <will@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Boqun Feng <boqun.feng@...il.com>,
Mark Rutland <mark.rutland@....com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Albert Ou <aou@...s.berkeley.edu>, Guo Ren <guoren@...nel.org>,
linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [RFC PATCH 1/1] riscv/atomic.h: Deduplicate arch_atomic.*
On Thu, May 25, 2023 at 7:07 AM Guo Ren <guoren@...nel.org> wrote:
>
> On Thu, May 25, 2023 at 5:31 PM Leonardo Bras Soares Passos
> <leobras@...hat.com> wrote:
> >
> > Friendly ping?
> >
> > On Wed, Apr 19, 2023 at 3:25 AM Leonardo Bras <leobras@...hat.com> wrote:
> > >
> > > Some functions use mostly the same asm for 32-bit and 64-bit versions.
> > >
> > > Make a macro that is generic enough and avoid code duplication.
> > >
> > > Signed-off-by: Leonardo Bras <leobras@...hat.com>
> > > ---
> > > arch/riscv/include/asm/atomic.h | 164 +++++++++++++++-----------------
> > > 1 file changed, 76 insertions(+), 88 deletions(-)
> > >
> > > diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
> > > index 0dfe9d857a762..85eb2edbc8219 100644
> > > --- a/arch/riscv/include/asm/atomic.h
> > > +++ b/arch/riscv/include/asm/atomic.h
> > > @@ -196,22 +196,28 @@ ATOMIC_OPS(xor, xor, i)
> > > #undef ATOMIC_FETCH_OP
> > > #undef ATOMIC_OP_RETURN
> > >
> > > +#define _arch_atomic_fetch_add_unless(_prev, _rc, counter, _a, _u, sfx) \
> > > +({ \
> > > + __asm__ __volatile__ ( \
> > > + "0: lr." sfx " %[p], %[c]\n" \
> > > + " beq %[p], %[u], 1f\n" \
> > > + " add %[rc], %[p], %[a]\n" \
> > > + " sc." sfx ".rl %[rc], %[rc], %[c]\n" \
> > > + " bnez %[rc], 0b\n" \
> > > + " fence rw, rw\n" \
> > > + "1:\n" \
> > > + : [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter) \
> > > + : [a]"r" (_a), [u]"r" (_u) \
> > > + : "memory"); \
> > > +})
> > > +
> > > /* This is required to provide a full barrier on success. */
> > > static __always_inline int arch_atomic_fetch_add_unless(atomic_t *v, int a, int u)
> > > {
> > > int prev, rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.w %[p], %[c]\n"
> > > - " beq %[p], %[u], 1f\n"
> > > - " add %[rc], %[p], %[a]\n"
> > > - " sc.w.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - : [a]"r" (a), [u]"r" (u)
> > > - : "memory");
> > > + _arch_atomic_fetch_add_unless(prev, rc, v->counter, a, u, "w");
> > > +
> > > return prev;
> > > }
> > > #define arch_atomic_fetch_add_unless arch_atomic_fetch_add_unless
> > > @@ -222,17 +228,8 @@ static __always_inline s64 arch_atomic64_fetch_add_unless(atomic64_t *v, s64 a,
> > > s64 prev;
> > > long rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.d %[p], %[c]\n"
> > > - " beq %[p], %[u], 1f\n"
> > > - " add %[rc], %[p], %[a]\n"
> > > - " sc.d.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - : [a]"r" (a), [u]"r" (u)
> > > - : "memory");
> > > + _arch_atomic_fetch_add_unless(prev, rc, v->counter, a, u, "d");
> > > +
> > > return prev;
> > > }
> > > #define arch_atomic64_fetch_add_unless arch_atomic64_fetch_add_unless
> > > @@ -310,61 +307,79 @@ ATOMIC_OPS()
> > > #undef ATOMIC_OPS
> > > #undef ATOMIC_OP
> > >
> > > +#define _arch_atomic_inc_unless_negative(_prev, _rc, counter, sfx) \
> > > +({ \
> > > + __asm__ __volatile__ ( \
> > > + "0: lr." sfx " %[p], %[c]\n" \
> > > + " bltz %[p], 1f\n" \
> > > + " addi %[rc], %[p], 1\n" \
> > > + " sc." sfx ".rl %[rc], %[rc], %[c]\n" \
> > > + " bnez %[rc], 0b\n" \
> > > + " fence rw, rw\n" \
> > > + "1:\n" \
> > > + : [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter) \
> > > + : \
> > > + : "memory"); \
> > > +})
> > > +
> > > static __always_inline bool arch_atomic_inc_unless_negative(atomic_t *v)
> > > {
> > > int prev, rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.w %[p], %[c]\n"
> > > - " bltz %[p], 1f\n"
> > > - " addi %[rc], %[p], 1\n"
> > > - " sc.w.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - :
> > > - : "memory");
> > > + _arch_atomic_inc_unless_negative(prev, rc, v->counter, "w");
> > > +
> > > return !(prev < 0);
> > > }
> > >
> > > #define arch_atomic_inc_unless_negative arch_atomic_inc_unless_negative
> > >
> > > +#define _arch_atomic_dec_unless_positive(_prev, _rc, counter, sfx) \
> > > +({ \
> > > + __asm__ __volatile__ ( \
> > > + "0: lr." sfx " %[p], %[c]\n" \
> > > + " bgtz %[p], 1f\n" \
> > > + " addi %[rc], %[p], -1\n" \
> > > + " sc." sfx ".rl %[rc], %[rc], %[c]\n" \
> > > + " bnez %[rc], 0b\n" \
> > > + " fence rw, rw\n" \
> > > + "1:\n" \
> > > + : [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter) \
> > > + : \
> > > + : "memory"); \
> > > +})
> > > +
> > > static __always_inline bool arch_atomic_dec_unless_positive(atomic_t *v)
> > > {
> > > int prev, rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.w %[p], %[c]\n"
> > > - " bgtz %[p], 1f\n"
> > > - " addi %[rc], %[p], -1\n"
> > > - " sc.w.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - :
> > > - : "memory");
> > > + _arch_atomic_dec_unless_positive(prev, rc, v->counter, "w");
> > > +
> > > return !(prev > 0);
> > > }
> > >
> > > #define arch_atomic_dec_unless_positive arch_atomic_dec_unless_positive
> > >
> > > +#define _arch_atomic_dec_if_positive(_prev, _rc, counter, sfx) \
> > > +({ \
> > > + __asm__ __volatile__ ( \
> > > + "0: lr." sfx " %[p], %[c]\n" \
> > > + " addi %[rc], %[p], -1\n" \
> > > + " bltz %[rc], 1f\n" \
> > > + " sc." sfx ".rl %[rc], %[rc], %[c]\n" \
> > > + " bnez %[rc], 0b\n" \
> > > + " fence rw, rw\n" \
> > > + "1:\n" \
> > > + : [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter) \
> > > + : \
> > > + : "memory"); \
> > > +})
> > > +
> > > static __always_inline int arch_atomic_dec_if_positive(atomic_t *v)
> > > {
> > > int prev, rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.w %[p], %[c]\n"
> > > - " addi %[rc], %[p], -1\n"
> > > - " bltz %[rc], 1f\n"
> > > - " sc.w.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - :
> > > - : "memory");
> > > + _arch_atomic_dec_if_positive(prev, rc, v->counter, "w");
> > > +
> > > return prev - 1;
> > > }
> > >
> > > @@ -376,17 +391,8 @@ static __always_inline bool arch_atomic64_inc_unless_negative(atomic64_t *v)
> > > s64 prev;
> > > long rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.d %[p], %[c]\n"
> > > - " bltz %[p], 1f\n"
> > > - " addi %[rc], %[p], 1\n"
> > > - " sc.d.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - :
> > > - : "memory");
> > > + _arch_atomic_inc_unless_negative(prev, rc, v->counter, "d");
> > > +
> > > return !(prev < 0);
> > > }
> > >
> > > @@ -397,17 +403,8 @@ static __always_inline bool arch_atomic64_dec_unless_positive(atomic64_t *v)
> > > s64 prev;
> > > long rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.d %[p], %[c]\n"
> > > - " bgtz %[p], 1f\n"
> > > - " addi %[rc], %[p], -1\n"
> > > - " sc.d.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - :
> > > - : "memory");
> > > + _arch_atomic_dec_unless_positive(prev, rc, v->counter, "d");
> > > +
> > > return !(prev > 0);
> > > }
> > >
> > > @@ -418,17 +415,8 @@ static __always_inline s64 arch_atomic64_dec_if_positive(atomic64_t *v)
> > > s64 prev;
> > > long rc;
> > >
> > > - __asm__ __volatile__ (
> > > - "0: lr.d %[p], %[c]\n"
> > > - " addi %[rc], %[p], -1\n"
> > > - " bltz %[rc], 1f\n"
> > > - " sc.d.rl %[rc], %[rc], %[c]\n"
> > > - " bnez %[rc], 0b\n"
> > > - " fence rw, rw\n"
> > > - "1:\n"
> > > - : [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)
> > > - :
> > > - : "memory");
> > > + _arch_atomic_dec_if_positive(prev, rc, v->counter, "d");
> > > +
> > > return prev - 1;
> > > }
> > >
> > > --
> > > 2.40.0
> > >
> >
> A safe cleanup, no problem found.
>
> Reviewed-by: Guo Ren <guoren@...nel.org>
>
>
Hello Palmer,
Any improvements you suggest for this patch?
Best regards,
Leonardo Bras
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