netdev - Re: [PATCH tip/core/rcu 21/21] drivers/vhost: Remove now-redundant read_barrier

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Message-ID: <20171205215700.GV3165@worktop.lehotels.local>
Date:   Tue, 5 Dec 2017 22:57:00 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, rostedt@...dmis.org,
        dhowells@...hat.com, edumazet@...gle.com, fweisbec@...il.com,
        oleg@...hat.com, Jason Wang <jasowang@...hat.com>,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH tip/core/rcu 21/21] drivers/vhost: Remove now-redundant
 read_barrier_depends()

On Tue, Dec 05, 2017 at 11:24:49PM +0200, Michael S. Tsirkin wrote:
> READ_ONCE is really all over the place (some code literally replaced all
> memory accesses with READ/WRITE ONCE).

Yeah, so? Complain to the compiler people for forcing us into that.

> Would an API like WRITE_POINTER()/smp_store_pointer make sense,
> and READ_POINTER for symmetry?

No, the whole point of the exercise was to get away from the fact that
dependent loads are special.