From: Jason Gunthorpe <jgg@ziepe.ca>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Arnd Bergmann <arnd@arndb.de>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
Sinan Kaya <okaya@codeaurora.org>,
David Laight <David.Laight@aculab.com>, Oliver <oohall@gmail.com>,
Alexander Duyck <alexander.h.duyck@redhat.com>,
"open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)"
<linuxppc-dev@lists.ozlabs.org>
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
WARNING: multiple messages have this Message-ID (diff)
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: 216+ 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 3:40 ` Oliver
2018-03-21 13:53 ` Sinan Kaya
2018-03-21 13:53 ` Sinan Kaya
2018-03-21 13:58 ` Sinan Kaya
2018-03-21 13:58 ` Sinan Kaya
2018-03-26 13:43 ` Arnd Bergmann
2018-03-26 13:43 ` Arnd Bergmann
2018-03-26 16:00 ` Sinan Kaya
2018-03-26 16:00 ` Sinan Kaya
2018-03-21 14:35 ` David Laight
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 8:20 ` Gabriel Paubert
2018-03-22 9:25 ` Oliver
2018-03-22 9:25 ` Oliver
2018-03-22 11:25 ` Gabriel Paubert
2018-03-22 11:25 ` Gabriel Paubert
2018-03-22 10:37 ` David Laight
2018-03-22 10:37 ` David Laight
2018-03-22 4:24 ` Benjamin Herrenschmidt
2018-03-22 4:24 ` Benjamin Herrenschmidt
2018-03-22 10:15 ` Oliver
2018-03-22 10:15 ` Oliver
2018-03-22 13:52 ` Benjamin Herrenschmidt
2018-03-22 13:52 ` Benjamin Herrenschmidt
2018-03-22 17:51 ` Sinan Kaya
2018-03-22 17:51 ` Sinan Kaya
2018-03-23 0:16 ` Benjamin Herrenschmidt
2018-03-23 0:16 ` Benjamin Herrenschmidt
2018-03-23 13:42 ` Sinan Kaya
2018-03-23 13:42 ` Sinan Kaya
2018-03-24 1:22 ` Benjamin Herrenschmidt
2018-03-24 1:22 ` Benjamin Herrenschmidt
2018-03-24 15:06 ` Sinan Kaya
2018-03-24 15:06 ` Sinan Kaya
2018-03-26 11:44 ` Will Deacon
2018-03-26 11:44 ` Will Deacon
2018-03-26 12:11 ` okaya
2018-03-26 12:11 ` okaya
2018-03-26 12:42 ` Sinan Kaya
2018-03-26 12:42 ` Sinan Kaya
2018-03-23 16:35 ` Jason Gunthorpe
2018-03-23 16:35 ` Jason Gunthorpe
2018-03-24 1:23 ` Benjamin Herrenschmidt
2018-03-24 1:23 ` Benjamin Herrenschmidt
2018-03-26 11:08 ` David Laight
2018-03-26 11:08 ` David Laight
2018-03-26 16:54 ` Jason Gunthorpe
2018-03-26 16:54 ` Jason Gunthorpe
2018-03-26 19:44 ` Arnd Bergmann
2018-03-26 19:44 ` Arnd Bergmann
2018-03-26 20:25 ` Jason Gunthorpe
2018-03-26 20:25 ` Jason Gunthorpe
2018-03-26 20:43 ` Arnd Bergmann
2018-03-26 20:43 ` Arnd Bergmann
2018-03-26 21:09 ` Jason Gunthorpe
2018-03-26 21:09 ` Jason Gunthorpe
2018-03-26 21:30 ` Arnd Bergmann
2018-03-26 21:30 ` Arnd Bergmann
2018-03-26 21:46 ` Sinan Kaya
2018-03-26 21:46 ` Sinan Kaya
2018-03-26 22:01 ` Benjamin Herrenschmidt
2018-03-26 22:01 ` Benjamin Herrenschmidt
2018-03-26 22:08 ` Sinan Kaya
2018-03-26 22:08 ` Sinan Kaya
2018-03-26 22:28 ` Benjamin Herrenschmidt
2018-03-26 22:28 ` Benjamin Herrenschmidt
2018-03-26 22:27 ` Jason Gunthorpe
2018-03-26 22:27 ` Jason Gunthorpe
2018-03-26 22:36 ` Benjamin Herrenschmidt
2018-03-26 22:36 ` Benjamin Herrenschmidt
2018-03-26 22:42 ` Benjamin Herrenschmidt
2018-03-26 22:42 ` Benjamin Herrenschmidt
2018-03-26 22:50 ` Jason Gunthorpe [this message]
2018-03-26 22:50 ` Jason Gunthorpe
2018-03-26 23:59 ` Benjamin Herrenschmidt
2018-03-26 23:59 ` Benjamin Herrenschmidt
2018-03-27 1:39 ` Jason Gunthorpe
2018-03-27 1:39 ` Jason Gunthorpe
2018-03-27 7:56 ` Arnd Bergmann
2018-03-27 7:56 ` Arnd Bergmann
2018-03-27 8:56 ` Benjamin Herrenschmidt
2018-03-27 8:56 ` Benjamin Herrenschmidt
2018-03-27 9:44 ` Arnd Bergmann
2018-03-27 9:44 ` Arnd Bergmann
2018-03-27 10:00 ` Will Deacon
2018-03-27 10:00 ` Will Deacon
2018-03-27 11:23 ` Benjamin Herrenschmidt
2018-03-27 11:23 ` Benjamin Herrenschmidt
2018-03-27 12:22 ` okaya
2018-03-27 12:22 ` okaya
2018-03-27 14:12 ` Jason Gunthorpe
2018-03-27 14:12 ` Jason Gunthorpe
2018-03-27 21:27 ` Benjamin Herrenschmidt
2018-03-27 21:27 ` Benjamin Herrenschmidt
2018-03-27 9:57 ` Will Deacon
2018-03-27 9:57 ` Will Deacon
2018-03-27 10:05 ` Arnd Bergmann
2018-03-27 10:05 ` Arnd Bergmann
2018-03-27 10:09 ` Will Deacon
2018-03-27 10:09 ` Will Deacon
2018-03-27 10:53 ` Arnd Bergmann
2018-03-27 10:53 ` Arnd Bergmann
2018-03-27 11:02 ` Will Deacon
2018-03-27 11:02 ` Will Deacon
2018-03-27 11:05 ` Arnd Bergmann
2018-03-27 11:05 ` Arnd Bergmann
2018-03-27 11:25 ` Benjamin Herrenschmidt
2018-03-27 11:25 ` Benjamin Herrenschmidt
2018-03-27 13:20 ` David Laight
2018-03-27 13:20 ` David Laight
2018-03-27 13:46 ` Sinan Kaya
2018-03-27 13:46 ` Sinan Kaya
2018-03-27 14:36 ` Will Deacon
2018-03-27 14:36 ` Will Deacon
2018-03-27 21:29 ` Benjamin Herrenschmidt
2018-03-27 21:29 ` Benjamin Herrenschmidt
2018-03-28 8:53 ` Will Deacon
2018-03-28 8:53 ` Will Deacon
2018-03-28 9:00 ` David Laight
2018-03-28 9:00 ` David Laight
2018-03-28 9:09 ` Will Deacon
2018-03-28 9:09 ` Will Deacon
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 9:50 ` Benjamin Herrenschmidt
2018-03-28 9:50 ` Benjamin Herrenschmidt
2018-03-28 9:55 ` Arnd Bergmann
2018-03-28 9:55 ` Arnd Bergmann
2018-03-28 10:01 ` Benjamin Herrenschmidt
2018-03-28 10:01 ` Benjamin Herrenschmidt
2018-03-28 10:13 ` Will Deacon
2018-03-28 10:13 ` Will Deacon
2018-03-28 16:57 ` Jason Gunthorpe
2018-03-28 16:57 ` Jason Gunthorpe
2018-03-29 9:19 ` Will Deacon
2018-03-29 9:19 ` Will Deacon
2018-03-29 14:45 ` Jason Gunthorpe
2018-03-29 14:45 ` Jason Gunthorpe
2018-03-29 14:58 ` David Laight
2018-03-29 14:58 ` David Laight
2018-03-29 16:40 ` Jason Gunthorpe
2018-03-29 16:40 ` Jason Gunthorpe
2018-03-27 21:24 ` Benjamin Herrenschmidt
2018-03-27 21:24 ` Benjamin Herrenschmidt
2018-03-27 11:21 ` Benjamin Herrenschmidt
2018-03-27 11:21 ` Benjamin Herrenschmidt
2018-03-27 9:42 ` Will Deacon
2018-03-27 9:42 ` Will Deacon
2018-03-27 11:20 ` Benjamin Herrenschmidt
2018-03-27 11:20 ` Benjamin Herrenschmidt
2018-03-27 11:24 ` Will Deacon
2018-03-27 11:24 ` Will Deacon
2018-03-27 14:24 ` Jason Gunthorpe
2018-03-27 14:24 ` Jason Gunthorpe
2018-03-27 14:16 ` Jason Gunthorpe
2018-03-27 14:16 ` Jason Gunthorpe
2018-03-26 22:00 ` Benjamin Herrenschmidt
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 19:54 ` Arnd Bergmann
2018-03-27 20:46 ` 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 6:53 ` Linus Torvalds
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 11:30 ` David Laight
2018-03-28 15:12 ` Benjamin Herrenschmidt
2018-03-28 16:16 ` David Laight
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
2018-03-26 21:26 ` Benjamin Herrenschmidt
2018-03-27 21:54 Alexander Duyck
2018-03-27 22:35 ` Sinan Kaya
2018-03-27 23:43 ` Benjamin Herrenschmidt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180326225046.GL15554@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=David.Laight@aculab.com \
--cc=alexander.h.duyck@redhat.com \
--cc=arnd@arndb.de \
--cc=benh@kernel.crashing.org \
--cc=linux-rdma@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=okaya@codeaurora.org \
--cc=oohall@gmail.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.