Messages in this thread |  | | Date | Mon, 13 Apr 2015 11:21:46 -0700 | Subject | Re: [PATCH v5 05/10] seqlock: Better document raw_write_seqcount_latch() | From | Linus Torvalds <> |
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On Mon, Apr 13, 2015 at 10:43 AM, Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > > A shorthand for READ_ONCE + smp_read_barrier_depends() is the shiny > new lockless_dereference()
Related side note - I think people should get used to seeing "smp_load_acquire()". It has well-defined memory ordering properties and should generally perform well on most architectures. It's (much) stronger than lockless_dereference(), and together with smp_store_release() you can make rather clear guarantees about passing data locklessly from one CPU to another.
I'd like to see us use more of the pattern of
- one thread does:
.. allocate/create some data smp_store_release() to "expose it"
- another thread does:
smp_load_acquire() to read index/pointer/flag/whatever .. use the data any damn way you want ..
and we should probably aim to prefer that pattern over a lot of our traditional memory barriers.
Linus
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