4.9-stable review patch. If anyone has any objections, please let me know.
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From: Matthias Kaehlcke mka@chromium.org
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'
Link: http://lkml.kernel.org/r/20170403190200.70273-1-mka@chromium.org Signed-off-by: Matthias Kaehlcke mka@chromium.org Cc: "Jason A . Donenfeld" Jason@zx2c4.com Cc: Grant Grundler grundler@chromium.org Cc: Michael Davidson md@google.com Cc: Greg Hackmann ghackmann@google.com Cc: Thomas Gleixner tglx@linutronix.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Cc: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/jiffies.h | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-)
--- a/include/linux/jiffies.h +++ b/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);