* [PATCH] riscv, atomic: Add #define's for the atomic_{cmp, }xchg_*() variants
@ 2018-12-01 0:01 Andrea Parri
2018-12-01 10:23 ` [PATCH] riscv, atomic: Add #define's for the atomic_{cmp,}xchg_*() variants Peter Zijlstra
0 siblings, 1 reply; 2+ messages in thread
From: Andrea Parri @ 2018-12-01 0:01 UTC (permalink / raw)
To: linux-kernel, linux-riscv
Cc: Andrea Parri, Albert Ou, Peter Zijlstra, Boqun Feng,
Palmer Dabbelt, Will Deacon
If an architecture does not define the atomic_{cmp,}xchg_*() variants,
the generic implementation defaults them to the fully-ordered version.
riscv's had its own variants since "the beginning", but it never told
(#define-d these for) the generic implementation: it is time to do so.
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
---
TBH, the delay was not intentional: I've just become aware of it while
working on moving riscv over to queued rwlocks. There's currently one
callsite for the non-fully-ordered variants mentioned above for riscv:
for atomic_cmpxchg_acquire() in kernel/sched/rt.c:rto_start_trylock(),
[before]
51a: 100726af lr.w a3,(a4)
51e: 00069763 bnez a3,52c <.L1\x027>
522: 1af7262f sc.w.rl a2,a5,(a4)
526: fa75 bnez a2,51a <.L\x021>
528: 0330000f fence rw,rw
[after]
51a: 100726af lr.w a3,(a4)
51e: 00069763 bnez a3,52c <.L1\x027>
522: 18f7262f sc.w a2,a5,(a4)
526: fa75 bnez a2,51a <.L\x021>
528: 0230000f fence r,rw
---
arch/riscv/include/asm/atomic.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
index c452359c9cb8a..93826771b616a 100644
--- a/arch/riscv/include/asm/atomic.h
+++ b/arch/riscv/include/asm/atomic.h
@@ -303,6 +303,15 @@ c_t atomic##prefix##_cmpxchg(atomic##prefix##_t *v, c_t o, c_t n) \
ATOMIC_OPS()
+#define atomic_xchg_relaxed atomic_xchg_relaxed
+#define atomic_xchg_acquire atomic_xchg_acquire
+#define atomic_xchg_release atomic_xchg_release
+#define atomic_xchg atomic_xchg
+#define atomic_cmpxchg_relaxed atomic_cmpxchg_relaxed
+#define atomic_cmpxchg_acquire atomic_cmpxchg_acquire
+#define atomic_cmpxchg_release atomic_cmpxchg_release
+#define atomic_cmpxchg atomic_cmpxchg
+
#undef ATOMIC_OPS
#undef ATOMIC_OP
--
2.17.1
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] riscv, atomic: Add #define's for the atomic_{cmp,}xchg_*() variants
2018-12-01 0:01 [PATCH] riscv, atomic: Add #define's for the atomic_{cmp, }xchg_*() variants Andrea Parri
@ 2018-12-01 10:23 ` Peter Zijlstra
0 siblings, 0 replies; 2+ messages in thread
From: Peter Zijlstra @ 2018-12-01 10:23 UTC (permalink / raw)
To: Andrea Parri
Cc: Albert Ou, Boqun Feng, Palmer Dabbelt, Will Deacon, linux-kernel,
linux-riscv
On Sat, Dec 01, 2018 at 01:01:56AM +0100, Andrea Parri wrote:
> If an architecture does not define the atomic_{cmp,}xchg_*() variants,
> the generic implementation defaults them to the fully-ordered version.
>
> riscv's had its own variants since "the beginning", but it never told
> (#define-d these for) the generic implementation: it is time to do so.
>
> Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
> Cc: Palmer Dabbelt <palmer@sifive.com>
> Cc: Albert Ou <aou@eecs.berkeley.edu>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/riscv/include/asm/atomic.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
> index c452359c9cb8a..93826771b616a 100644
> --- a/arch/riscv/include/asm/atomic.h
> +++ b/arch/riscv/include/asm/atomic.h
> @@ -303,6 +303,15 @@ c_t atomic##prefix##_cmpxchg(atomic##prefix##_t *v, c_t o, c_t n) \
>
> ATOMIC_OPS()
>
> +#define atomic_xchg_relaxed atomic_xchg_relaxed
> +#define atomic_xchg_acquire atomic_xchg_acquire
> +#define atomic_xchg_release atomic_xchg_release
> +#define atomic_xchg atomic_xchg
> +#define atomic_cmpxchg_relaxed atomic_cmpxchg_relaxed
> +#define atomic_cmpxchg_acquire atomic_cmpxchg_acquire
> +#define atomic_cmpxchg_release atomic_cmpxchg_release
> +#define atomic_cmpxchg atomic_cmpxchg
> +
> #undef ATOMIC_OPS
> #undef ATOMIC_OP
>
> --
> 2.17.1
>
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2018-12-01 10:23 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-12-01 0:01 [PATCH] riscv, atomic: Add #define's for the atomic_{cmp, }xchg_*() variants Andrea Parri
2018-12-01 10:23 ` [PATCH] riscv, atomic: Add #define's for the atomic_{cmp,}xchg_*() variants Peter Zijlstra
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).