Patch "jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp" has been added to the 4.9-stable tree

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

jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp

to the 4.9-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:
jiffies.h-declare-jiffies-and-jiffies_64-with-____cacheline_aligned_in_smp.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Matthias Kaehlcke <[email protected]>
Date: Mon, 8 May 2017 15:55:05 -0700
Subject: jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp

From: Matthias Kaehlcke <[email protected]>

commit 7c30f352c852bae2715ad65ac4a38ca9af7d7696 upstream.

jiffies_64 is defined in kernel/time/timer.c with ____cacheline_aligned_in_smp, however this macro is not part of the declaration of jiffies and jiffies_64 in jiffies.h.

As a result clang generates the following warning:

kernel/time/timer.c:57:26: error: section does not match previous declaration [-Werror,-Wsection]

  __visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
                           ^
  include/linux/cache.h:39:36: note: expanded from macro '__cacheline_aligned_in_smp'
                                     ^
  include/linux/cache.h:34:4: note: expanded from macro '__cacheline_aligned'
                   __section__(".data..cacheline_aligned")))
                   ^
  include/linux/jiffies.h:77:12: note: previous attribute is here
  extern u64 __jiffy_data jiffies_64;
             ^

include/linux/jiffies.h:70:38: note: expanded from macro '__jiffy_data'

---
 include/linux/jiffies.h |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

@@ -1,6 +1,7 @@
 #ifndef _LINUX_JIFFIES_H
 #define _LINUX_JIFFIES_H
 
+#include <linux/cache.h>
 #include <linux/math64.h>
 #include <linux/kernel.h>
 #include <linux/types.h>

@@ -63,19 +64,13 @@ extern int register_refined_jiffies(long
 /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
 #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
 
-/* some arch's have a small-data section that can be accessed register-relative
- * but that can only take up to, say, 4-byte variables. jiffies being part of
- * an 8-byte variable may not be correctly accessed unless we force the issue
- */
-#define __jiffy_data  __attribute__((section(".data")))
-
 /*
  * The 64-bit value is not atomic - you MUST NOT read it
  * without sampling the sequence number in jiffies_lock.
  * get_jiffies_64() will do this for you as appropriate.
  */
-extern u64 __jiffy_data jiffies_64;
-extern unsigned long volatile __jiffy_data jiffies;
+extern u64 __cacheline_aligned_in_smp jiffies_64;
+extern unsigned long volatile __cacheline_aligned_in_smp jiffies;
 
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void);

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

queue-4.9/dm-ioctl-remove-double-parentheses.patch queue-4.9/genirq-use-cpumask_available-for-check-of-cpumask-variable.patch queue-4.9/fs-compat-remove-warning-from-compatible_ioctl.patch queue-4.9/jiffies.h-declare-jiffies-and-jiffies_64-with-____cacheline_aligned_in_smp.patch queue-4.9/selinux-remove-unnecessary-check-of-array-base-in-selinux_set_mapping.patch queue-4.9/pci-make-pci_rom_address_mask-a-32-bit-constant.patch queue-4.9/frv-declare-jiffies-to-be-located-in-the-.data-section.patch queue-4.9/cpumask-add-helper-cpumask_available.patch