| Message ID | 20180523133533.1076-11-mark.rutland@arm.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | atomics: API cleanups | expand |
Hi Mark, Mark Rutland <mark.rutland@arm.com> writes: > As a step towards unifying the atomic/atomic64/atomic_long APIs, this > patch converts the arch/powerpc implementation of atomic64_add_unless() > into an implementation of atomic64_fetch_add_unless(). > > A wrapper in <linux/atomic.h> will build atomic_add_unless() atop of > this, provided it is given a preprocessor definition. > > No functional change is intended as a result of this patch. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Michael Ellerman <mpe@ellerman.id.au> > --- > arch/powerpc/include/asm/atomic.h | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h > index b5646c079c16..233dbf31911c 100644 > --- a/arch/powerpc/include/asm/atomic.h > +++ b/arch/powerpc/include/asm/atomic.h > @@ -525,7 +525,7 @@ static __inline__ long atomic64_dec_if_positive(atomic64_t *v) > #define atomic64_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new)) > > /** > - * atomic64_add_unless - add unless the number is a given value > + * atomic64_fetch_add_unless - add unless the number is a given value > * @v: pointer of type atomic64_t > * @a: the amount to add to v... > * @u: ...unless v is equal to u. > @@ -533,13 +533,13 @@ static __inline__ long atomic64_dec_if_positive(atomic64_t *v) > * Atomically adds @a to @v, so long as it was not @u. > * Returns the old value of @v. Comment was wrong, but is right now. Win. > */ > -static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) > +static __inline__ long atomic64_fetch_add_unless(atomic64_t *v, long a, long u) > { > long t; > > __asm__ __volatile__ ( > PPC_ATOMIC_ENTRY_BARRIER > -"1: ldarx %0,0,%1 # atomic_fetch_add_unless\n\ > +"1: ldarx %0,0,%1 # atomic64_fetch_add_unless\n\ > cmpd 0,%0,%3 \n\ > beq 2f \n\ > add %0,%2,%0 \n" We overwrite t here with the new value ... > @@ -552,8 +552,9 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) But then in the context above here we do: " subf %0,%2,%0 \n\ Which puts the old value back into t. > : "r" (&v->counter), "r" (a), "r" (u) > : "cc", "memory"); > > - return t != u; > + return t; ie. this is correct. I'm not sure why we wrote it that way, to add and then subtract, but that's not your problem. So LGTM. Acked-by: Michael Ellerman <mpe@ellerman.id.au> cheers
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h index b5646c079c16..233dbf31911c 100644 --- a/arch/powerpc/include/asm/atomic.h +++ b/arch/powerpc/include/asm/atomic.h @@ -525,7 +525,7 @@ static __inline__ long atomic64_dec_if_positive(atomic64_t *v) #define atomic64_xchg_relaxed(v, new) xchg_relaxed(&((v)->counter), (new)) /** - * atomic64_add_unless - add unless the number is a given value + * atomic64_fetch_add_unless - add unless the number is a given value * @v: pointer of type atomic64_t * @a: the amount to add to v... * @u: ...unless v is equal to u. @@ -533,13 +533,13 @@ static __inline__ long atomic64_dec_if_positive(atomic64_t *v) * Atomically adds @a to @v, so long as it was not @u. * Returns the old value of @v. */ -static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) +static __inline__ long atomic64_fetch_add_unless(atomic64_t *v, long a, long u) { long t; __asm__ __volatile__ ( PPC_ATOMIC_ENTRY_BARRIER -"1: ldarx %0,0,%1 # atomic_fetch_add_unless\n\ +"1: ldarx %0,0,%1 # atomic64_fetch_add_unless\n\ cmpd 0,%0,%3 \n\ beq 2f \n\ add %0,%2,%0 \n" @@ -552,8 +552,9 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) : "r" (&v->counter), "r" (a), "r" (u) : "cc", "memory"); - return t != u; + return t; } +#define atomic64_fetch_add_unless atomic64_fetch_add_unless /** * atomic_inc64_not_zero - increment unless the number is zero
As a step towards unifying the atomic/atomic64/atomic_long APIs, this patch converts the arch/powerpc implementation of atomic64_add_unless() into an implementation of atomic64_fetch_add_unless(). A wrapper in <linux/atomic.h> will build atomic_add_unless() atop of this, provided it is given a preprocessor definition. No functional change is intended as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/include/asm/atomic.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) -- 2.11.0