Messages in this thread | | | Date | Tue, 21 Nov 2006 08:39:39 +0100 | From | Jens Axboe <> | Subject | Re: [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync |
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On Mon, Nov 20 2006, Alan Stern wrote: > On Mon, 20 Nov 2006, Jens Axboe wrote: > > > > > Must we introduce memory allocations in srcu_read_lock()? It makes it > > > > much harder and nastier for me to use. I'd much prefer a failing > > > > init_srcu(), seems like a much better API. > > > > > > Paul agrees with you that allocation failures in init_srcu() should be > > > passed back to the caller, and I certainly don't mind doing so. > > > > > > However we can't remove the memory allocation in srcu_read_lock(). That > > > was the point which started this whole thread: the per-cpu allocation > > > cannot be done statically, and some users of a static SRCU structure can't > > > easily call init_srcu() early enough. > > > > > > Once the allocation succeeds, the overhead in srcu_read_lock() is minimal. > > > > It's not about the overhead, it's about a potentially problematic > > allocation. > > I'm not sure what you mean by "problematic allocation". If you > successfully call init_srcu_struct then the allocation will be taken care > of. Later calls to srcu_read_lock won't experience any slowdowns or > problems.
That requires init_srcu_struct() to return the error. If it does that, I'm fine with it.
> Does this answer your objection? If not, can you explain in more detail > what other features you would like?
It does, if the allocation failure in init_srcu_struct() is signalled.
-- Jens Axboe
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