Il 14/02/2014 08:51, Srivatsa S. Bhat ha scritto:
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 kvm code in arm by using this latter form of callback registration. Cc: Christoffer Dall <christoffer.d...@linaro.org> Cc: Gleb Natapov <g...@kernel.org> Cc: Paolo Bonzini <pbonz...@redhat.com> Cc: Russell King <li...@arm.linux.org.uk> Cc: Ingo Molnar <mi...@kernel.org> Cc: kvm...@lists.cs.columbia.edu Cc: k...@vger.kernel.org Cc: linux-arm-ker...@lists.infradead.org Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com> --- arch/arm/kvm/arm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 1d8248e..147b917 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -1050,21 +1050,26 @@ int kvm_arch_init(void *opaque) } } + cpu_notifier_register_begin(); + err = init_hyp_mode(); if (err) goto out_err; - err = register_cpu_notifier(&hyp_init_cpu_nb); + err = __register_cpu_notifier(&hyp_init_cpu_nb); if (err) { kvm_err("Cannot register HYP init CPU notifier (%d)\n", err); goto out_err; } + cpu_notifier_register_done(); + hyp_cpu_pm_init(); kvm_coproc_table_init(); return 0; out_err: + cpu_notifier_register_done(); return err; }
Acked-by: Paolo Bonzini <pbonz...@redhat.com> -- 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/
