DPDK patches and discussions
 help / color / mirror / Atom feed
From: Thomas Monjalon <thomas@monjalon.net>
To: Gavin Hu <gavin.hu@arm.com>
Cc: dev@dpdk.org, "Ananyev,
	Konstantin" <konstantin.ananyev@intel.com>,
	"nd@arm.com" <nd@arm.com>,
	"jerinj@marvell.com" <jerinj@marvell.com>,
	"hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>,
	"nipun.gupta@nxp.com" <nipun.gupta@nxp.com>,
	"Honnappa.Nagarahalli@arm.com" <Honnappa.Nagarahalli@arm.com>,
	"i.maximets@samsung.com" <i.maximets@samsung.com>,
	"chaozhu@linux.vnet.ibm.com" <chaozhu@linux.vnet.ibm.com>,
	"stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3 1/1] ring: enforce reading the tail before reading ring slots
Date: Thu, 28 Mar 2019 01:21:55 +0100	[thread overview]
Message-ID: <1963883.zIr16fWVUr@xps> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB977258013655C014@irsmsx105.ger.corp.intel.com>

> > In weak memory models, like arm64, reading the prod.tail may get
> > reordered after reading the ring slots, which corrupts the ring and
> > stale data is observed.
> > 
> > This issue was reported by NXP on 8-A72 DPAA2 board. The problem is most
> > likely caused by missing the acquire semantics when reading
> > prod.tail (in SC dequeue) which makes it possible to read a
> > stale value from the ring slots.
> > 
> > For MP (and MC) case, rte_atomic32_cmpset() already provides the required
> > ordering. For SP case, the control depependency between if-statement(which
> > depends on the read of r->cons.tail) and the later stores to the ring slots
> > make RMB unnecessary. About the control dependency, read more at:
> > https://www.cl.cam.ac.uk/~pes20/ppc-supplemental/test7.pdf
> > 
> > This patch is adding the required read barrier to prevent reading the ring
> > slots get reordered before reading prod.tail for SC case.
> > 
> > Fixes: c9fb3c62896f ("ring: move code in a new header file")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: gavin hu <gavin.hu@arm.com>
> > Reviewed-by: Ola Liljedahl <Ola.Liljedahl@arm.com>
> > Tested-by: Nipun Gupta <nipun.gupta@nxp.com>
> 
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

Applied, thanks

  parent reply	other threads:[~2019-03-28  0:22 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-06  3:07 [dpdk-dev] [PATCH v1] ring: enforce reading the tails before ring operations gavin hu
     [not found] ` <CGME20190306114906eucas1p19c2572b1fe777e1eb0ca96d2e47295bd@eucas1p1.samsung.com>
2019-03-06 11:49   ` [dpdk-dev] [v1] " Ilya Maximets
2019-03-07  6:50     ` Gavin Hu (Arm Technology China)
2019-03-07  6:45 ` [dpdk-dev] [PATCH v2] " gavin hu
2019-03-07  8:52   ` Ilya Maximets
2019-03-07  9:27     ` Gavin Hu (Arm Technology China)
2019-03-07  9:48       ` Ilya Maximets
2019-03-07 10:44         ` Gavin Hu (Arm Technology China)
2019-03-07 11:17           ` Ananyev, Konstantin
2019-03-08  3:21             ` Honnappa Nagarahalli
2019-03-08  5:27               ` Gavin Hu (Arm Technology China)
2019-03-08 16:33                 ` Ananyev, Konstantin
2019-03-10 20:47                   ` Honnappa Nagarahalli
2019-03-11 13:58                     ` Ananyev, Konstantin
2019-03-08  4:23           ` Gavin Hu (Arm Technology China)
2019-03-08  5:06             ` Honnappa Nagarahalli
2019-03-08 12:13             ` Ananyev, Konstantin
2019-03-08 15:05               ` Gavin Hu (Arm Technology China)
2019-03-08 15:50                 ` Ananyev, Konstantin
2019-03-08 23:18                   ` Thomas Monjalon
2019-03-08 23:48                     ` Honnappa Nagarahalli
2019-03-09 10:28                       ` Gavin Hu (Arm Technology China)
2019-03-12 16:58 ` [dpdk-dev] [PATCH v3 0/1] ring: enforce reading the tail before reading ring slots Gavin Hu
2019-03-12 16:58 ` [dpdk-dev] [PATCH v3 1/1] " Gavin Hu
2019-03-13  8:12   ` Nipun Gupta
2019-03-15 13:26   ` Ananyev, Konstantin
2019-03-15 13:26     ` Ananyev, Konstantin
2019-03-28  0:21     ` Thomas Monjalon [this message]
2019-03-28  0:21       ` Thomas Monjalon

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=1963883.zIr16fWVUr@xps \
    --to=thomas@monjalon.net \
    --cc=Honnappa.Nagarahalli@arm.com \
    --cc=chaozhu@linux.vnet.ibm.com \
    --cc=dev@dpdk.org \
    --cc=gavin.hu@arm.com \
    --cc=hemant.agrawal@nxp.com \
    --cc=i.maximets@samsung.com \
    --cc=jerinj@marvell.com \
    --cc=konstantin.ananyev@intel.com \
    --cc=nd@arm.com \
    --cc=nipun.gupta@nxp.com \
    --cc=stable@dpdk.org \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).