On Tue, 3 Sep 2013 16:45:45 +0200 Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote: > 2013/9/3 Christoph Lameter <cl@xxxxxxxxx>: > > On Thu, 29 Aug 2013, Steven Rostedt wrote: > > > >> How many places use the this_cpu_*() without preemption disabled? I > >> wouldn't think there's many. I never complained about another variant, > >> so you need to ask those that have. The tough question for me is what > >> that variant name should be ;-) > > > > Tried to add preemption checks but the basic issue is that many of the > > checks themselves use this_cpu_ops. percpu.h is very basic to the > > operation of fundamental primitives for preempt etc. Use of a BUG_ON needs > > a seris of includes in percpu.h that cause more trouble. > > > > If I switch __this_cpu ops to check for preemption then the logic for > > preemption etc must use the raw_this_cpu ops. > > IIUC the issue is that preempt debug checks themselves use per cpu > operations that can result in preempt debug checks? Hence a recursion. > Do you have an example of that? > > Also in this case this must be fixed anyway given the checks that > already exist in smp_processor_id(), __get_cpu_var(), ... Right, that's why there's a raw_smp_processor_id() and __raw_get_cpu_var(). Those two are the ones without checks, and they are called by the non "raw" versions after the check is done. Really, what's so damn hard about this? -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
