Messages in this thread | | | Date | Tue, 20 Mar 2018 09:23:59 -0600 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v4 1/6] RDMA/bnxt_re: Eliminate duplicate barriers on weakly-ordered archs |
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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
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