On Mon, Jun 7, 2021 at 9:26 AM Viresh Kumar [off-list ref] wrote:

Hi Rafael,

On Mon, May 24, 2021 at 7:47 PM Rafael J. Wysocki [off-list ref] wrote:

quoted

On Sat, May 22, 2021 at 12:19 AM Kyle Meyer [off-list ref] wrote:

quoted

quoted

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 7e7450453714..e79a945369d1 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c

@@ -1003,7 +1003,7 @@ static int __init acpi_cpufreq_init(void)

        /* don't keep reloading if cpufreq_driver exists */
        if (cpufreq_get_current_driver())
-               return -EEXIST;
+               return 0;

        pr_debug("%s\n", __func__);

--

Applied as 5.14 material with some edits in the subject and changelog, thanks!

I am not sure how this is supposed to work. If we return 0 from
acpi_cpufreq_init(),
then the driver will never be used, since it's acpi_cpufreq_init()
will never get
called again later.

Unless the module is unloaded and loaded again, that is.

cpufreq drivers don't follow the generic device/driver model where a driver gets
probed again if a device appears and so this is broken.

It is broken anyway as per the changelog of this patch.

On systems with several hundred logical CPUs this really can be troublesome.

Please revert this patch.

Well, you can argue that the problem at hand is outside the kernel and
so it's not a kernel's business to address it.

After all, systemd-udevd could learn to avoid attempting to load the
module again if it fails with -EEXIST, but I'm not sure how different
that really would be from what this patch does, in practice.