Messages in this thread | | | Subject | Re: [PATCH v5 3/3] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2 | From | Sinan Kaya <> | Date | Tue, 3 Apr 2018 13:47:05 -0400 |
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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.
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