Messages in this thread | | | Date | Tue, 20 Sep 2011 09:57:32 -0500 (CDT) | From | Christoph Lameter <> | Subject | Re: [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write() |
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On Tue, 20 Sep 2011, Valdis.Kletnieks@vt.edu wrote:
> On Mon, 19 Sep 2011 23:06:17 EDT, Steven Rostedt said: > > > It is really confusing to know which version to use. I'm confused by the > > this_cpu_*() compared with __this_cpu_*(). I'm guessing that most places > > should use __this_cpu*(). But really this_cpu() should be the default, > > and the places that can have it outside of preemption should have > > another name. Maybe use the raw_this_cpu() or safe_this_cpu(), as there > > is an irqsafe_this_cpu(). Maybe make a preemptsafe_cpu_*(). There should > > only be a very few locations that are OK to have preemption enabled when > > calling the this_cpu() code. Lets have those have the funny names and > > not be the default "this_cpu_*()".
this_cpu_xx functions are made for those locations that have preemption enabled. If you can use those function (classic case is a per cpu counter increment in the network subsystem) then you can avoid preempt disable/enable or get_cpu/put_cpu.
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