kernel/reboot: Use static handler for register_platform_power_off()

The register_platform_power_off() fails on m68k platform due to the
memory allocation error that happens at a very early boot time when
memory allocator isn't available yet. Fix it by using a static sys-off
handler for the platform-level power-off handlers.

Fixes: f0f7e5265b3b ("m68k: Switch to new sys-off handler API")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/reboot.c b/kernel/reboot.c
index a091145ee7104bb2750f69f0885554c393c7bb62..3b19b123efecb2aee1cc76e5317eb8607b3397e9 100644 (file)
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -315,6 +315,37 @@ static int sys_off_notify(struct notifier_block *nb,
        return handler->sys_off_cb(&data);
 }
 
+static struct sys_off_handler platform_sys_off_handler;
+
+static struct sys_off_handler *alloc_sys_off_handler(int priority)
+{
+       struct sys_off_handler *handler;
+
+       /*
+        * Platforms like m68k can't allocate sys_off handler dynamically
+        * at the early boot time because memory allocator isn't available yet.
+        */
+       if (priority == SYS_OFF_PRIO_PLATFORM) {
+               handler = &platform_sys_off_handler;
+               if (handler->cb_data)
+                       return ERR_PTR(-EBUSY);
+       } else {
+               handler = kzalloc(sizeof(*handler), GFP_KERNEL);
+               if (!handler)
+                       return ERR_PTR(-ENOMEM);
+       }
+
+       return handler;
+}
+
+static void free_sys_off_handler(struct sys_off_handler *handler)
+{
+       if (handler == &platform_sys_off_handler)
+               memset(handler, 0, sizeof(*handler));
+       else
+               kfree(handler);
+}
+
 /**
  *     register_sys_off_handler - Register sys-off handler
  *     @mode: Sys-off mode
@@ -345,9 +376,9 @@ register_sys_off_handler(enum sys_off_mode mode,
        struct sys_off_handler *handler;
        int err;
 
-       handler = kzalloc(sizeof(*handler), GFP_KERNEL);
-       if (!handler)
-               return ERR_PTR(-ENOMEM);
+       handler = alloc_sys_off_handler(priority);
+       if (IS_ERR(handler))
+               return handler;
 
        switch (mode) {
        case SYS_OFF_MODE_POWER_OFF_PREPARE:
@@ -364,7 +395,7 @@ register_sys_off_handler(enum sys_off_mode mode,
                break;
 
        default:
-               kfree(handler);
+               free_sys_off_handler(handler);
                return ERR_PTR(-EINVAL);
        }
 
@@ -391,7 +422,7 @@ register_sys_off_handler(enum sys_off_mode mode,
        }
 
        if (err) {
-               kfree(handler);
+               free_sys_off_handler(handler);
                return ERR_PTR(err);
        }
 
@@ -422,7 +453,7 @@ void unregister_sys_off_handler(struct sys_off_handler *handler)
        /* sanity check, shall never happen */
        WARN_ON(err);
 
-       kfree(handler);
+       free_sys_off_handler(handler);
 }
 EXPORT_SYMBOL_GPL(unregister_sys_off_handler);