From: Jason Gunthorpe <jgg@ziepe.ca>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Sinan Kaya <okaya@codeaurora.org>, Arnd Bergmann <arnd@arndb.de>,
David Laight <David.Laight@aculab.com>, Oliver <oohall@gmail.com>,
"open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)"
<linuxppc-dev@lists.ozlabs.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
Alexander Duyck <alexander.h.duyck@redhat.com>,
Will Deacon <will.deacon@arm.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: RFC on writel and writel_relaxed
Date: Mon, 26 Mar 2018 16:50:46 -0600 [thread overview]
Message-ID: <20180326225046.GL15554@ziepe.ca> (raw)
In-Reply-To: <1522103771.7364.20.camel@kernel.crashing.org>
On Tue, Mar 27, 2018 at 09:36:11AM +1100, Benjamin Herrenschmidt wrote:
> On Mon, 2018-03-26 at 16:27 -0600, Jason Gunthorpe wrote:
> > > Otherwise almost all drivers out there are broken which I very much
> > > doubt :-)
> >
> > But.. Sinan is right, you look anywhere in the driver tree and you
> > find stuff like this:
> >
> > drivers/net/ethernet/intel/i40e/i40e_txrx.c
> >
> > /* Force memory writes to complete before letting h/w
> > * know there are new descriptors to fetch.
> > */
> > wmb();
> >
> >
> > It is *systemic*
>
> Yes, because they all copied e1000e :-) If you look at the comment in
> there, it does say it's only for weakly ordered archs such as ia64, and
> even then, probably predates Linus strong statement on the matter.
Hahah, sure I'll buy that..
But still, if this really is the case, a *strong* statement in
barriers.txt to that effect (and not an example demanding the wmb()!)
would be very helpful for those of us that have to review driver code!
Jason
next prev parent reply other threads:[~2018-03-26 22:50 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-21 3:07 RFC on writel and writel_relaxed Sinan Kaya
2018-03-21 3:40 ` Oliver
2018-03-21 13:53 ` Sinan Kaya
2018-03-21 13:58 ` Sinan Kaya
2018-03-26 13:43 ` Arnd Bergmann
2018-03-26 16:00 ` Sinan Kaya
2018-03-21 14:35 ` David Laight
2018-03-21 15:04 ` Sinan Kaya
2018-03-22 5:24 ` Oliver
2018-03-22 8:20 ` Gabriel Paubert
2018-03-22 9:25 ` Oliver
2018-03-22 11:25 ` Gabriel Paubert
2018-03-22 10:37 ` David Laight
2018-03-22 4:24 ` Benjamin Herrenschmidt
2018-03-22 10:15 ` Oliver
2018-03-22 13:52 ` Benjamin Herrenschmidt
2018-03-22 17:51 ` Sinan Kaya
2018-03-23 0:16 ` Benjamin Herrenschmidt
2018-03-23 13:42 ` Sinan Kaya
2018-03-24 1:22 ` Benjamin Herrenschmidt
2018-03-24 15:06 ` Sinan Kaya
2018-03-26 11:44 ` Will Deacon
2018-03-26 12:11 ` okaya
2018-03-26 12:42 ` Sinan Kaya
2018-03-23 16:35 ` Jason Gunthorpe
2018-03-24 1:23 ` Benjamin Herrenschmidt
2018-03-26 11:08 ` David Laight
2018-03-26 16:54 ` Jason Gunthorpe
2018-03-26 19:44 ` Arnd Bergmann
2018-03-26 20:25 ` Jason Gunthorpe
2018-03-26 20:43 ` Arnd Bergmann
2018-03-26 21:09 ` Jason Gunthorpe
2018-03-26 21:30 ` Arnd Bergmann
2018-03-26 21:46 ` Sinan Kaya
2018-03-26 22:01 ` Benjamin Herrenschmidt
2018-03-26 22:08 ` Sinan Kaya
2018-03-26 22:28 ` Benjamin Herrenschmidt
2018-03-26 22:27 ` Jason Gunthorpe
2018-03-26 22:36 ` Benjamin Herrenschmidt
2018-03-26 22:42 ` Benjamin Herrenschmidt
2018-03-26 22:50 ` Jason Gunthorpe [this message]
2018-03-26 23:59 ` Benjamin Herrenschmidt
2018-03-27 1:39 ` Jason Gunthorpe
2018-03-27 7:56 ` Arnd Bergmann
2018-03-27 8:56 ` Benjamin Herrenschmidt
2018-03-27 9:44 ` Arnd Bergmann
2018-03-27 10:00 ` Will Deacon
2018-03-27 11:23 ` Benjamin Herrenschmidt
2018-03-27 12:22 ` okaya
2018-03-27 14:12 ` Jason Gunthorpe
2018-03-27 21:27 ` Benjamin Herrenschmidt
2018-03-27 9:57 ` Will Deacon
2018-03-27 10:05 ` Arnd Bergmann
2018-03-27 10:09 ` Will Deacon
2018-03-27 10:53 ` Arnd Bergmann
2018-03-27 11:02 ` Will Deacon
2018-03-27 11:05 ` Arnd Bergmann
2018-03-27 11:25 ` Benjamin Herrenschmidt
2018-03-27 13:20 ` David Laight
2018-03-27 13:46 ` Sinan Kaya
2018-03-27 14:36 ` Will Deacon
2018-03-27 21:29 ` Benjamin Herrenschmidt
2018-03-28 8:53 ` Will Deacon
2018-03-28 9:00 ` David Laight
2018-03-28 9:09 ` Will Deacon
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 9:50 ` Benjamin Herrenschmidt
2018-03-28 9:55 ` Arnd Bergmann
2018-03-28 10:01 ` Benjamin Herrenschmidt
2018-03-28 10:13 ` Will Deacon
2018-03-28 16:57 ` Jason Gunthorpe
2018-03-29 9:19 ` Will Deacon
2018-03-29 14:45 ` Jason Gunthorpe
2018-03-29 14:58 ` David Laight
2018-03-29 16:40 ` Jason Gunthorpe
2018-03-27 21:24 ` Benjamin Herrenschmidt
2018-03-27 11:21 ` Benjamin Herrenschmidt
2018-03-27 9:42 ` Will Deacon
2018-03-27 11:20 ` Benjamin Herrenschmidt
2018-03-27 11:24 ` Will Deacon
2018-03-27 14:24 ` Jason Gunthorpe
2018-03-27 14:16 ` Jason Gunthorpe
2018-03-26 22:00 ` Benjamin Herrenschmidt
2018-03-27 14:46 ` Sinan Kaya
2018-03-27 15:01 ` Jose Abreu
2018-03-27 15:10 ` Will Deacon
2018-03-27 18:54 ` Alexander Duyck
2018-03-27 19:54 ` Arnd Bergmann
2018-03-27 20:46 ` Arnd Bergmann
2018-03-27 21:33 ` Benjamin Herrenschmidt
2018-03-28 0:39 ` Linus Torvalds
2018-03-28 1:03 ` Benjamin Herrenschmidt
2018-03-28 2:51 ` Linus Torvalds
2018-03-28 3:24 ` Sinan Kaya
2018-03-28 4:41 ` Benjamin Herrenschmidt
2018-03-28 6:14 ` Linus Torvalds
2018-03-28 11:41 ` okaya
2018-03-28 15:13 ` Benjamin Herrenschmidt
2018-03-28 15:55 ` David Miller
2018-03-28 16:23 ` Nicholas Piggin
2018-03-28 21:31 ` Benjamin Herrenschmidt
2018-03-28 22:09 ` Nicholas Piggin
2018-03-29 9:20 ` Will Deacon
2018-03-29 13:56 ` Sinan Kaya
2018-03-29 14:04 ` David Miller
2018-03-29 16:29 ` Arnd Bergmann
2018-03-29 16:59 ` Sinan Kaya
2018-03-30 1:40 ` Benjamin Herrenschmidt
2018-04-02 13:01 ` Sinan Kaya
2018-03-28 4:33 ` Benjamin Herrenschmidt
2018-03-28 6:26 ` Linus Torvalds
2018-03-28 6:42 ` Benjamin Herrenschmidt
2018-03-28 6:53 ` Linus Torvalds
2018-03-28 6:56 ` Benjamin Herrenschmidt
2018-03-28 7:11 ` Arnd Bergmann
2018-03-28 7:42 ` Benjamin Herrenschmidt
2018-03-28 9:07 ` Will Deacon
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 10:13 ` Aw: " Lino Sanfilippo
2018-03-28 10:20 ` Benjamin Herrenschmidt
2018-03-28 11:30 ` David Laight
2018-03-28 15:12 ` Benjamin Herrenschmidt
2018-03-28 16:16 ` David Laight
2018-03-28 1:21 ` Benjamin Herrenschmidt
2018-03-27 21:35 ` Benjamin Herrenschmidt
2018-03-26 21:26 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2018-03-27 21:54 Alexander Duyck
2018-03-27 22:35 ` Sinan Kaya
2018-03-27 23:43 ` Benjamin Herrenschmidt
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