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From: David Laight <David.Laight@ACULAB.COM>
To: 'Nicholas Piggin' <npiggin@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
	"paulus@samba.org" <paulus@samba.org>,
	"anton@samba.org" <anton@samba.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: RE: [PATCH v9 14/14] powerpc: rewrite local_t using soft_irq
Date: Fri, 4 Aug 2017 15:18:08 +0000	[thread overview]
Message-ID: <063D6719AE5E284EB5DD2968C1650D6DD004B4AD@AcuExch.aculab.com> (raw)
In-Reply-To: <20170804190429.3383e932@roar.ozlabs.ibm.com>

From: Nicholas Piggin
> Sent: 04 August 2017 10:04
> On Fri, 04 Aug 2017 11:40:43 +1000
> Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>=20
> > On Fri, 2017-08-04 at 03:50 +1000, Nicholas Piggin wrote:
> > > Hey, so... why are any of these implemented in asm? We should
> > > just do them all in C, right? I looked a bit harder at code gen
> > > and a couple of them are still emitting larx/stcx.
> >
> > As long as we can guarantee that the C compiler won't play games
> > moving stuff around. But yes, I tend to agree.
>=20
>=20
> I believe so. I mean we already depend on the same pattern for any
> other sequence of local_irq_disable(); c code; local_irq_enable();
> so we'd have other problems if we couldn't.

I'd guess that a "memory" clobber on the irq_disable/enable would be enough=
.
It could be restricted to the memory area being updated.

	David

      reply	other threads:[~2017-08-04 15:18 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-03  3:49 [PATCH v9 00/14]powerpc: "paca->soft_enabled" based local atomic operation implementation Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 01/14] powerpc: Add #defs for paca->soft_enabled flags Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 02/14] powerpc: move set_soft_enabled() and rename Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 03/14] powerpc: Use soft_enabled_set api to update paca->soft_enabled Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 04/14] powerpc: Add soft_enabled manipulation functions Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 05/14] powerpc/irq: Cleanup hard_irq_disable() macro Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 06/14] powerpc/irq: Fix arch_local_irq_disable() in book3s Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 07/14] powerpc: Modify soft_enable from flag to mask Madhavan Srinivasan
2017-08-03  4:44   ` Nicholas Piggin
2017-08-03  3:49 ` [PATCH v9 08/14] powerpc: Rename soft_enabled to soft_disable_mask Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 09/14] powerpc: Avoid using EXCEPTION_PROLOG_1 macro in MASKABLE_* Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 10/14] powerpc: Add support to take additional parameter in MASKABLE_* macro Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 11/14] Add support to mask perf interrupts and replay them Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 12/14] powerpc:Add new kconfig IRQ_DEBUG_SUPPORT Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 13/14] powerpc: Add new set of soft_disable_mask_ functions Madhavan Srinivasan
2017-08-03  3:49 ` [PATCH v9 14/14] powerpc: rewrite local_t using soft_irq Madhavan Srinivasan
2017-08-03 17:50   ` Nicholas Piggin
2017-08-04  1:40     ` Benjamin Herrenschmidt
2017-08-04  9:04       ` Nicholas Piggin
2017-08-04 15:18         ` David Laight [this message]

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