From: Ralf Baechle <ralf@linux-mips.org>
To: Nick Piggin <npiggin@suse.de>, dhowells@redhat.com
Cc: linux-arch@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [rfc] io memory barriers, and getting rid of mmiowb
Date: Wed, 21 Nov 2007 13:50:16 +0000 [thread overview]
Message-ID: <20071121135016.GB15318@linux-mips.org> (raw)
In-Reply-To: <20071120160220.GA22196@wotan.suse.de>
On Tue, Nov 20, 2007 at 05:02:20PM +0100, Nick Piggin wrote:
> + TYPE FULL CACHEABLE (SMP CONDITIONAL) IO
> + ========= ======================= =========================== ============
> + GENERAL mb() smp_mb() io_mb()
> + WRITE wmb() smp_wmb() io_wmb()
> + READ rmb() smp_rmb() io_rmb()
> + DATA DEP. read_barrier_depends() smp_read_barrier_depends()
A while ago I went through the kernel looking at the uses mb(), wmb() and
rmb() and found that every use was either fishy or should have been a
smp_mb(), smp_wmb() or wmp_rmb(). Which leads me to the question if there
is any need for the non-smp_ variants left or can we just bury them?
Ralf
next prev parent reply other threads:[~2007-11-21 13:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-20 16:02 [rfc] io memory barriers, and getting rid of mmiowb Nick Piggin
2007-11-20 16:46 ` David Howells
2007-11-20 16:58 ` Matthew Wilcox
2007-11-20 17:04 ` David Howells
2007-11-21 0:30 ` Nick Piggin
2007-11-21 1:53 ` David Howells
2007-11-22 8:23 ` Nick Piggin
2007-11-21 13:50 ` Ralf Baechle [this message]
2007-11-22 8:04 ` Nick Piggin
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