From: Sinan Kaya <okaya@codeaurora.org>
To: "Kalderon, Michal" <Michal.Kalderon@cavium.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"timur@codeaurora.org" <timur@codeaurora.org>,
"sulrich@codeaurora.org" <sulrich@codeaurora.org>
Cc: "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"Elior, Ariel" <Ariel.Elior@cavium.com>,
Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 3/3] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2
Date: Tue, 3 Apr 2018 13:47:05 -0400 [thread overview]
Message-ID: <3f8de63a-9036-a5ac-2369-2d9af80bb6ef@codeaurora.org> (raw)
In-Reply-To: <CY1PR0701MB201215C9F38E8760732B595088A50@CY1PR0701MB2012.namprd07.prod.outlook.com>
On 4/3/2018 3:42 AM, Kalderon, Michal wrote:
> The wmb before writel are used to make sure the
> HW observes the changes in memory before we trigger the doorbell.
According to Linus, writel() guarantees observability. No extra
barrier is necessary.
https://www.mail-archive.com/netdev@vger.kernel.org/msg225806.html
There shouldn't be any wmb() in drivers unless it is used for a
very well-known reason.
APIs like readX() and writeX() guarantee observability.
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2018-04-03 17:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1521736009-23387-1-git-send-email-okaya@codeaurora.org>
2018-03-22 16:26 ` [PATCH v5 1/3] RDMA/bnxt_re: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-22 16:26 ` [PATCH v5 2/3] RDMA/i40iw: " Sinan Kaya
2018-03-23 19:15 ` Sinan Kaya
2018-03-22 16:26 ` [PATCH v5 3/3] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2 Sinan Kaya
2018-04-03 2:29 ` Sinan Kaya
2018-04-03 7:42 ` Kalderon, Michal
2018-04-03 17:47 ` Sinan Kaya [this message]
2018-04-03 20:03 ` Jason Gunthorpe
2018-04-04 11:54 ` Kalderon, Michal
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