Re: [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write()

Andi Kleen
2011-09-20T02:20:31Z

Steven Rostedt <rostedt@goodmis.org> writes:

> I just found out that the this_cpu_*() functions do not perform the
> test to see if the usage is in atomic or not. Thus, the blind
> conversion of the per_cpu(*, smp_processor_id()) and the get_cpu_var()
> code to this_cpu_*() introduce the regression to detect the hard
> to find case where a per cpu variable is used in preempt code that
> migrates and causes bugs.

Didn't preempt-rt recently get changed to not migrate in kernel-preempt
regions. How about just fixing the normal preemption to not do this
either.

Then all these complications wouldn't be necessary and a whole lot
of code related to this could be removed too, and you would still
have less bugs.

-Andi

--
ak@linux.intel.com -- Speaking for myself only