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Subject[PATCH v1] kernel/reboot: Use static handler for register_platform_power_off()
Date
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>
---
kernel/reboot.c | 43 +++++++++++++++++++++++++++++++++++++------
1 file changed, 37 insertions(+), 6 deletions(-)

diff --git a/kernel/reboot.c b/kernel/reboot.c
index a091145ee710..3b19b123efec 100644
--- 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);

--
2.35.3
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