From: Jason Gunthorpe <jgg@ziepe.ca>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: linux-rdma@vger.kernel.org, timur@codeaurora.org,
sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Selvin Xavier <selvin.xavier@broadcom.com>,
Devesh Sharma <devesh.sharma@broadcom.com>,
Somnath Kotur <somnath.kotur@broadcom.com>,
Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>,
Doug Ledford <dledford@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/6] RDMA/bnxt_re: Eliminate duplicate barriers on weakly-ordered archs
Date: Tue, 20 Mar 2018 09:23:59 -0600 [thread overview]
Message-ID: <20180320152359.GL19744@ziepe.ca> (raw)
In-Reply-To: <3e6cfa25-6b9f-24ff-499a-6df2740b658b@codeaurora.org>
On Tue, Mar 20, 2018 at 10:08:16AM -0500, Sinan Kaya wrote:
> Never mind, it will break some architectures. I'll only change the first one.
>
> (1) On some systems, I/O stores are not strongly ordered across all CPUs, and
> so for _all_ general drivers locks should be used and mmiowb() must be
> issued prior to unlocking the critical section.
I think the kernel could do well to have a spin_unlock_mmiowb()
function. We have this patern quite a bit.
Arches like x86 can just make it == spin_unlock, while PPC and ARM can
add their extra barriers.
Then we can safely and efficiently use _realxed within such a
spinlock region.
Jason
WARNING: multiple messages have this Message-ID (diff)
From: jgg@ziepe.ca (Jason Gunthorpe)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 1/6] RDMA/bnxt_re: Eliminate duplicate barriers on weakly-ordered archs
Date: Tue, 20 Mar 2018 09:23:59 -0600 [thread overview]
Message-ID: <20180320152359.GL19744@ziepe.ca> (raw)
In-Reply-To: <3e6cfa25-6b9f-24ff-499a-6df2740b658b@codeaurora.org>
On Tue, Mar 20, 2018 at 10:08:16AM -0500, Sinan Kaya wrote:
> Never mind, it will break some architectures. I'll only change the first one.
>
> (1) On some systems, I/O stores are not strongly ordered across all CPUs, and
> so for _all_ general drivers locks should be used and mmiowb() must be
> issued prior to unlocking the critical section.
I think the kernel could do well to have a spin_unlock_mmiowb()
function. We have this patern quite a bit.
Arches like x86 can just make it == spin_unlock, while PPC and ARM can
add their extra barriers.
Then we can safely and efficiently use _realxed within such a
spinlock region.
Jason
next prev parent reply other threads:[~2018-03-20 15:23 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 2:47 [PATCH v4 0/6] ib: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 2:47 ` [PATCH v4 1/6] RDMA/bnxt_re: " Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 14:48 ` Jason Gunthorpe
2018-03-20 14:48 ` Jason Gunthorpe
2018-03-20 15:00 ` Sinan Kaya
2018-03-20 15:00 ` Sinan Kaya
2018-03-20 15:08 ` Sinan Kaya
2018-03-20 15:08 ` Sinan Kaya
2018-03-20 15:23 ` Jason Gunthorpe [this message]
2018-03-20 15:23 ` Jason Gunthorpe
2018-03-20 15:20 ` Jason Gunthorpe
2018-03-20 15:20 ` Jason Gunthorpe
2018-03-20 15:30 ` Sinan Kaya
2018-03-20 15:30 ` Sinan Kaya
2018-03-20 16:02 ` Jason Gunthorpe
2018-03-20 16:02 ` Jason Gunthorpe
2018-03-20 2:47 ` [PATCH v4 2/6] IB/mlx4: " Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 14:48 ` Jason Gunthorpe
2018-03-20 14:48 ` Jason Gunthorpe
2018-03-20 2:47 ` [PATCH v4 3/6] RDMA/i40iw: " Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 14:56 ` Jason Gunthorpe
2018-03-20 14:56 ` Jason Gunthorpe
2018-03-21 13:38 ` Shiraz Saleem
2018-03-21 13:38 ` Shiraz Saleem
2018-03-21 20:02 ` Jason Gunthorpe
2018-03-21 20:02 ` Jason Gunthorpe
2018-03-21 21:01 ` Sinan Kaya
2018-03-21 21:01 ` Sinan Kaya
2018-03-20 2:47 ` [PATCH v4 4/6] infiniband: cxgb4: " Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 14:51 ` Jason Gunthorpe
2018-03-20 14:51 ` Jason Gunthorpe
2018-03-20 15:10 ` Steve Wise
2018-03-20 15:10 ` Steve Wise
2018-03-20 15:38 ` Steve Wise
2018-03-20 15:38 ` Steve Wise
2018-03-22 6:44 ` kbuild test robot
2018-03-22 6:44 ` kbuild test robot
2018-03-22 12:24 ` okaya
2018-03-22 12:24 ` okaya at codeaurora.org
2018-03-22 12:48 ` okaya
2018-03-22 12:48 ` okaya at codeaurora.org
2018-03-22 14:33 ` Sinan Kaya
2018-03-22 14:33 ` Sinan Kaya
2018-03-22 14:40 ` Steve Wise
2018-03-22 14:40 ` Steve Wise
2018-03-22 14:52 ` Sinan Kaya
2018-03-22 14:52 ` Sinan Kaya
2018-03-22 16:28 ` Steve Wise
2018-03-22 16:28 ` Steve Wise
2018-03-22 19:44 ` Casey Leedom
2018-03-22 19:44 ` Casey Leedom
2018-03-22 20:16 ` Jason Gunthorpe
2018-03-22 20:16 ` Jason Gunthorpe
2018-03-22 20:45 ` Casey Leedom
2018-03-22 20:45 ` Casey Leedom
2018-03-22 21:25 ` Jason Gunthorpe
2018-03-22 21:25 ` Jason Gunthorpe
2018-03-22 21:27 ` Sinan Kaya
2018-03-22 21:27 ` Sinan Kaya
2018-03-22 22:02 ` Casey Leedom
2018-03-22 22:02 ` Casey Leedom
[not found] ` <437ab002-b8db-24aa-583e-0e61d61aaa97@codeaurora.org>
2018-03-22 18:46 ` Jason Gunthorpe
2018-03-22 18:46 ` Jason Gunthorpe
2018-03-22 18:48 ` Jason Gunthorpe
2018-03-22 18:48 ` Jason Gunthorpe
2018-03-22 18:58 ` Sinan Kaya
2018-03-22 18:58 ` Sinan Kaya
2018-03-23 4:14 ` kbuild test robot
2018-03-23 4:14 ` kbuild test robot
2018-03-20 2:47 ` [PATCH v4 5/6] IB/nes: " Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 14:54 ` Jason Gunthorpe
2018-03-20 14:54 ` Jason Gunthorpe
2018-03-20 15:23 ` Sinan Kaya
2018-03-20 15:23 ` Sinan Kaya
2018-03-20 16:01 ` Jason Gunthorpe
2018-03-20 16:01 ` Jason Gunthorpe
2018-03-20 16:08 ` Sinan Kaya
2018-03-20 16:08 ` Sinan Kaya
2018-03-20 16:29 ` Jason Gunthorpe
2018-03-20 16:29 ` Jason Gunthorpe
2018-03-20 2:47 ` [PATCH v4 6/6] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2 Sinan Kaya
2018-03-20 2:47 ` Sinan Kaya
2018-03-20 7:38 ` Kalderon, Michal
2018-03-20 7:38 ` Kalderon, Michal
2018-03-20 14:55 ` Jason Gunthorpe
2018-03-20 14:55 ` Jason Gunthorpe
2018-03-21 20:08 ` [PATCH v4 0/6] ib: Eliminate duplicate barriers on weakly-ordered archs Jason Gunthorpe
2018-03-21 20:08 ` Jason Gunthorpe
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