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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alexander Duyck <alexander.h.duyck@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Peter Zijlstra <peterz@infradead.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Michael Neuling <mikey@neuling.org>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	donald.c.skidmore@intel.com, matthew.vick@intel.com,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	Francois Romieu <romieu@fr.zoreil.com>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	nic_swsd@realtek.com, Will Deacon <will.deacon@arm.com>,
	Michael Ellerman <michael@ellerman.id.au>,
	Tony Luck <tony.luck@intel.com>, Oleg Nesterov <oleg@redhat.com>,
	Martin Schwidefsky <sch>
Subject: Re: [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb()
Date: Tue, 18 Nov 2014 11:43:32 +1100	[thread overview]
Message-ID: <1416271412.18381.20.camel@kernel.crashing.org> (raw)
In-Reply-To: <546A6EB2.6020304@redhat.com>

On Mon, 2014-11-17 at 13:54 -0800, Alexander Duyck wrote:

> What would you think of the name "coherent_*mb()"?  I would prefer to 
> avoid dma in the name since, at least in my mind, that implies MMIO.

I'm lazy, I like typing less, so I like dma_* but I don't object to
coherent_* if at least one more person thinks it makes the semantics
clearer :)

> It also ties in well with dma_alloc_coherent/dma_free_coherent which is 
> what would typically be used to allocate the memory we would be using 
> the barrier to protect anyway.

Agreed.

> > And yes, in the same spirit, it would probably be good to try to
> > eventually get rid of the plain "*mb()" functions, and perhaps call
> > them "mmio_*mb()" to clarify that they are about ordering memory wrt
> > mmio.
> >
> > Hmm?
> >
> >                          Linus
> 
> I will work on pulling all of the coherent barrier cases out of using 
> the plain "*mb()" calls first.  We need to sort that out before we could 
> look at renaming the plain barrier functions.

Makes sense.

Cheers,
Ben.

> - Alex
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alexander Duyck <alexander.h.duyck@redhat.com>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"Network Development" <netdev@vger.kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Mathieu Desnoyers" <mathieu.desnoyers@polymtl.ca>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Heiko Carstens" <heiko.carstens@de.ibm.com>,
	"Ingo Molnar" <mingo@kernel.org>,
	"Michael Neuling" <mikey@neuling.org>,
	"Russell King - ARM Linux" <linux@arm.linux.org.uk>,
	donald.c.skidmore@intel.com, matthew.vick@intel.com,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	"Jeff Kirsher" <jeffrey.t.kirsher@intel.com>,
	"Francois Romieu" <romieu@fr.zoreil.com>,
	"Paul McKenney" <paulmck@linux.vnet.ibm.com>,
	nic_swsd@realtek.com, "Will Deacon" <will.deacon@arm.com>,
	"Michael Ellerman" <michael@ellerman.id.au>,
	"Tony Luck" <tony.luck@intel.com>,
	"Oleg Nesterov" <oleg@redhat.com>,
	"Martin Schwidefsky" <schwidefsky@de.ibm.com>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"David Miller" <davem@davemloft.net>
Subject: Re: [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb()
Date: Tue, 18 Nov 2014 11:43:32 +1100	[thread overview]
Message-ID: <1416271412.18381.20.camel@kernel.crashing.org> (raw)
Message-ID: <20141118004332.UznkgymgqVJseNNgLzyf_7SXvmKJC1fTcNm2I5WnqKs@z> (raw)
In-Reply-To: <546A6EB2.6020304@redhat.com>

On Mon, 2014-11-17 at 13:54 -0800, Alexander Duyck wrote:

> What would you think of the name "coherent_*mb()"?  I would prefer to 
> avoid dma in the name since, at least in my mind, that implies MMIO.

I'm lazy, I like typing less, so I like dma_* but I don't object to
coherent_* if at least one more person thinks it makes the semantics
clearer :)

> It also ties in well with dma_alloc_coherent/dma_free_coherent which is 
> what would typically be used to allocate the memory we would be using 
> the barrier to protect anyway.

Agreed.

> > And yes, in the same spirit, it would probably be good to try to
> > eventually get rid of the plain "*mb()" functions, and perhaps call
> > them "mmio_*mb()" to clarify that they are about ordering memory wrt
> > mmio.
> >
> > Hmm?
> >
> >                          Linus
> 
> I will work on pulling all of the coherent barrier cases out of using 
> the plain "*mb()" calls first.  We need to sort that out before we could 
> look at renaming the plain barrier functions.

Makes sense.

Cheers,
Ben.

> - Alex
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/



WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alexander Duyck <alexander.h.duyck@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Peter Zijlstra <peterz@infradead.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Michael Neuling <mikey@neuling.org>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	donald.c.skidmore@intel.com, matthew.vick@intel.com,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	Francois Romieu <romieu@fr.zoreil.com>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	nic_swsd@realtek.com, Will Deacon <will.deacon@arm.com>,
	Michael Ellerman <michael@ellerman.id.au>,
	Tony Luck <tony.luck@intel.com>, Oleg Nesterov <oleg@redhat.com>,
	Martin Schwidefsky <sch
Subject: Re: [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb()
Date: Tue, 18 Nov 2014 11:43:32 +1100	[thread overview]
Message-ID: <1416271412.18381.20.camel@kernel.crashing.org> (raw)
In-Reply-To: <546A6EB2.6020304@redhat.com>

On Mon, 2014-11-17 at 13:54 -0800, Alexander Duyck wrote:

> What would you think of the name "coherent_*mb()"?  I would prefer to 
> avoid dma in the name since, at least in my mind, that implies MMIO.

I'm lazy, I like typing less, so I like dma_* but I don't object to
coherent_* if at least one more person thinks it makes the semantics
clearer :)

> It also ties in well with dma_alloc_coherent/dma_free_coherent which is 
> what would typically be used to allocate the memory we would be using 
> the barrier to protect anyway.

Agreed.

> > And yes, in the same spirit, it would probably be good to try to
> > eventually get rid of the plain "*mb()" functions, and perhaps call
> > them "mmio_*mb()" to clarify that they are about ordering memory wrt
> > mmio.
> >
> > Hmm?
> >
> >                          Linus
> 
> I will work on pulling all of the coherent barrier cases out of using 
> the plain "*mb()" calls first.  We need to sort that out before we could 
> look at renaming the plain barrier functions.

Makes sense.

Cheers,
Ben.

> - Alex
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

  reply	other threads:[~2014-11-18  0:43 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-17 17:17 [PATCH 0/4] Add lightweight memory barriers fast_rmb() and fast_wmb() Alexander Duyck
2014-11-17 17:17 ` [PATCH 1/4] arch: Cleanup read_barrier_depends() and comments Alexander Duyck
2014-11-17 17:18 ` [PATCH 2/4] arch: Add lightweight memory barriers fast_rmb() and fast_wmb() Alexander Duyck
2014-11-17 20:04   ` Benjamin Herrenschmidt
2014-11-17 20:24     ` Alexander Duyck
2014-11-18  0:39       ` Benjamin Herrenschmidt
2014-11-18  3:13         ` Alexander Duyck
2014-11-18 11:58           ` Will Deacon
2014-11-18 11:58             ` Will Deacon
2014-11-18 11:58             ` Will Deacon
2014-11-18 16:20             ` Alexander Duyck
2014-11-18 16:20               ` Alexander Duyck
2014-11-18 16:20               ` Alexander Duyck
2014-11-18 16:48               ` Will Deacon
2014-11-18 16:48                 ` Will Deacon
2014-11-18 16:48                 ` Will Deacon
2014-11-18 21:07           ` Benjamin Herrenschmidt
2014-11-17 20:18   ` Paul E. McKenney
2014-11-17 21:11     ` Alexander Duyck
2014-11-17 23:17       ` Paul E. McKenney
2014-11-18  3:33         ` Alexander Duyck
2014-11-18  0:38     ` Benjamin Herrenschmidt
2014-11-17 20:52   ` Linus Torvalds
2014-11-17 20:52     ` Linus Torvalds
2014-11-17 20:52     ` Linus Torvalds
2014-11-17 21:54     ` Alexander Duyck
2014-11-17 21:54       ` Alexander Duyck
2014-11-17 21:54       ` Alexander Duyck
2014-11-18  0:43       ` Benjamin Herrenschmidt [this message]
2014-11-18  0:43         ` Benjamin Herrenschmidt
2014-11-18  0:43         ` Benjamin Herrenschmidt
2014-11-18  0:41     ` Benjamin Herrenschmidt
2014-11-18  0:41       ` Benjamin Herrenschmidt
2014-11-18  0:41       ` Benjamin Herrenschmidt
2014-11-17 17:18 ` [PATCH 3/4] r8169: Use fast_rmb() and fast_wmb() for DescOwn checks Alexander Duyck
2014-11-17 17:18 ` [PATCH 4/4] fm10k/igb/ixgbe: Use fast_rmb on Rx descriptor reads Alexander Duyck
2014-11-17 21:32   ` Jeff Kirsher
2014-11-18  9:57 ` [PATCH 0/4] Add lightweight memory barriers fast_rmb() and fast_wmb() David Laight
2014-11-18  9:57   ` David Laight
2014-11-18  9:57   ` David Laight
2014-11-18 15:44   ` Alexander Duyck
2014-11-18 15:44     ` Alexander Duyck

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