jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp
authorMatthias Kaehlcke <mka@chromium.org>
Mon, 8 May 2017 22:55:05 +0000 (15:55 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 9 May 2017 00:15:10 +0000 (17:15 -0700)
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'
  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>

index 624215cebee5235a3375549f62e026b3c7e41f74..36872fbb815d72203e14582e3dab6ba5051ee8a7 100644 (file)
@@ -1,6 +1,7 @@
+#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 clock_tick_rate);
 /* 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);