Messages in this thread | | | Date | Sun, 19 Jan 2014 11:56:02 -0800 | Subject | Re: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock() | From | Linus Torvalds <> |
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On Sun, Jan 19, 2014 at 12:04 AM, Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > > OK, another approach would be to never add "select ARCH_USE_QUEUE_RWLOCK" > on Alpha, at least if the queued rwlocks really do want to atomically > manipulate bytes. After all, the Alpha systems that I know about don't > have enough CPUs to make queued rwlocks necessary anyway. > > Much simpler solution! > > Is this what you were getting at, or am I missing your point?
You're missing something.
Just make the "writer" field be an "int" on little-endian archiectures (like alpha).
There is no reason for that field to be a "char" to begin with, as far as I can tell, since the padding of the structure means that it doesn't save any space. But even if that wasn't true, we could make an arch-specific type for "minimum type for locking".
So my *point* was that it should be easy enough to just make sure that any data structures used for locking have types that are appropriate for that locking.
Linus
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