From 7291edca20215dfdf0eb841881d63753448ef09c Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 2 Aug 2019 21:49:29 -0700 Subject: [PATCH] drivers/acpi/scan.c: document why we don't need the device_hotplug_lock Let's document why the lock is not needed in acpi_scan_init(), right now this is not really obvious. [akpm@linux-foundation.org: fix tpyo] Link: http://lkml.kernel.org/r/20190731135306.31524-1-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Rafael J. Wysocki Cc: Oscar Salvador Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/acpi/scan.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index 0e28270b0fd8..aad6be5c0af0 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. -- 2.30.2