From: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Subject: jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp
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'
Link: http://lkml.kernel.org/r/20170403190200.70273-1-mka@xxxxxxxxxxxx
Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Cc: "Jason A . Donenfeld" <Jason@xxxxxxxxx>
Cc: Grant Grundler <grundler@xxxxxxxxxxxx>
Cc: Michael Davidson <md@xxxxxxxxxx>
Cc: Greg Hackmann <ghackmann@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/jiffies.h | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff -puN include/linux/jiffies.h~jiffiesh-declare-jiffies-and-jiffies_64-with-____cacheline_aligned_in_smp include/linux/jiffies.h
--- a/include/linux/jiffies.h~jiffiesh-declare-jiffies-and-jiffies_64-with-____cacheline_aligned_in_smp
+++ a/include/linux/jiffies.h
@@ -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);
_
--
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