Let's document why the lock is not needed in acpi_scan_init(), right now this is not really obvious. Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Oscar Salvador <osalvador@xxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> --- @Andrew, can you drop "drivers/acpi/scan.c: acquire device_hotplug_lock in acpi_scan_init()" and add this patch instead? Thanks --- drivers/acpi/scan.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index 0e28270b0fd8..8444af6cd514 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -2204,6 +2204,12 @@ int __init acpi_scan_init(void) acpi_gpe_apply_masked_gpes(); acpi_update_all_gpes(); + /* + * Although we call__add_memory() that is documented to require the + * device_hotplug_lock, it is not necessary here because this is an + * early code when userspace or any other code path cannot trigger + * hotplug/hotunplug operations. + */ mutex_lock(&acpi_scan_lock); /* * Enumerate devices in the ACPI namespace. -- 2.21.0
