Patch "i2c: remove __init from i2c_register_board_info()" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

i2c: remove __init from i2c_register_board_info()

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
i2c-remove-__init-from-i2c_register_board_info.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Luis R. Rodriguez" <[email protected]>
Date: Tue, 7 Jun 2016 16:52:27 -0700
Subject: i2c: remove __init from i2c_register_board_info()

From: Luis R. Rodriguez <[email protected]>

commit 5abe9b26847c65a698f38744a52635b287514294 upstream.

As of next-20160607 with allyesconfig we get this linker failure:

MODPOST vmlinux.o
WARNING: vmlinux.o(.text+0x21bc0d): Section mismatch in reference from the function intel_scu_devices_create() to the function .init.text:i2c_register_board_info()

This is caused by the fact that intel_scu_devices_create() calls i2c_register_board_info() and intel_scu_devices_create() is not annotated with __init. This typically involves manual code inspection and if one is certain this is correct we would just peg intel_scu_devices_create() with a __ref annotation.

In this case this would be wrong though as the intel_scu_devices_create() call is exported, and used in the ipc_probe() on drivers/platform/x86/intel_scu_ipc.c. The issue is that even though builtin_pci_driver(ipc_driver) is used this just exposes the probe routine, which can occur at any point in time if this bus supports hotplug. A race can happen between kernel_init_freeable() that calls the init calls (in this case registeres the intel_scu_ipc.c driver, and later free_initmem(), which would free the i2c_register_board_info(). If a probe happens later in boot i2c_register_board_info() would not be present and we should get a page fault.

---
 drivers/i2c/i2c-boardinfo.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

@@ -56,9 +56,7 @@ EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bu
  * The board info passed can safely be __initdata, but be careful of embedded
  * pointers (for platform_data, functions, etc) since that won't be copied.
  */
-int __init
-i2c_register_board_info(int busnum,
-	struct i2c_board_info const *info, unsigned len)
+int i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned len)
 {
 	int status;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/i2c-remove-__init-from-i2c_register_board_info.patch