On 02/14/2014 11:05 PM, Bjorn Helgaas wrote: > On Fri, Feb 14, 2014 at 12:55 AM, Srivatsa S. Bhat > <srivatsa.b...@linux.vnet.ibm.com> wrote: >> Subsystems that want to register CPU hotplug callbacks, as well as perform >> initialization for the CPUs that are already online, often do it as shown >> below: >> >> get_online_cpus(); >> >> for_each_online_cpu(cpu) >> init_cpu(cpu); >> >> register_cpu_notifier(&foobar_cpu_notifier); >> >> put_online_cpus(); >> >> This is wrong, since it is prone to ABBA deadlocks involving the >> cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently >> with CPU hotplug operations). >> >> Instead, the correct and race-free way of performing the callback >> registration is: >> >> cpu_notifier_register_begin(); >> >> for_each_online_cpu(cpu) >> init_cpu(cpu); >> >> /* Note the use of the double underscored version of the API */ >> __register_cpu_notifier(&foobar_cpu_notifier); >> >> cpu_notifier_register_done(); >> >> >> Fix the amd-bus code in x86 by using this latter form of callback >> registration. >> >> Cc: Bjorn Helgaas <bhelg...@google.com> >> Cc: Thomas Gleixner <t...@linutronix.de> >> Cc: Ingo Molnar <mi...@kernel.org> >> Cc: "H. Peter Anvin" <h...@zytor.com> >> Cc: x...@kernel.org >> Cc: linux-...@vger.kernel.org >> Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com> > > This looks fine to me. > > Acked-by: Bjorn Helgaas <bhelg...@google.com> > > I think it makes sense for you to merge it along with all your other > similar changes. I don't foresee any conflicts with things in my PCI > tree. >
Great! Thank you! Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
