cpufreq: return EEXIST instead of EBUSY for second registering

On systems that support intel_pstate, acpi_cpufreq fails to load, and
udev keeps trying until trace gets filled up and kernel crashes.

The root cause is driver return ret from cpufreq_register_driver(),
because when some other driver takes over before, it will return
EBUSY and then udev will keep trying ...

cpufreq_register_driver() should return EEXIST instead so that the
system can boot without appending intel_pstate=disable and still use
intel_pstate.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 82ecbe39dfb0b6e8ada2fe72e3365107b1d79b72..89b3c52cd5c3a61a7961358dea59009c3ce2de02 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2104,7 +2104,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
        write_lock_irqsave(&cpufreq_driver_lock, flags);
        if (cpufreq_driver) {
                write_unlock_irqrestore(&cpufreq_driver_lock, flags);
-               return -EBUSY;
+               return -EEXIST;
        }
        cpufreq_driver = driver_data;
        write_unlock_irqrestore(&cpufreq_driver_lock, flags);