[PATCH] simplify update_times (avoid jiffies/jiffies_64 aliasing problem)

Pass ticks to do_timer() and update_times(), and adjust x86_64 and s390
timer interrupt handler with this change.

Currently update_times() calculates ticks by "jiffies - wall_jiffies", but
callers of do_timer() should know how many ticks to update.  Passing ticks
get rid of this redundant calculation.  Also there are another redundancy
pointed out by Martin Schwidefsky.

This cleanup make a barrier added by
5aee405c662ca644980c184774277fc6d0769a84 needless.  So this patch removes
it.

As a bonus, this cleanup make wall_jiffies can be removed easily, since now
wall_jiffies is always synced with jiffies.  (This patch does not really
remove wall_jiffies.  It would be another cleanup patch)

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Hirokazu Takata <takata.hirokazu@renesas.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 1981c6199fa2..abab42e9f5f8 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -166,7 +166,7 @@ EXPORT_SYMBOL(do_settimeofday);
 void account_ticks(struct pt_regs *regs)
 {
         __u64 tmp;
-        __u32 ticks, xticks;
+        __u32 ticks;
 
         /* Calculate how many ticks have passed. */
         if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) {
@@ -204,6 +204,7 @@ void account_ticks(struct pt_regs *regs)
          */
         write_seqlock(&xtime_lock);
         if (S390_lowcore.jiffy_timer > xtime_cc) {
+                __u32 xticks;
                 tmp = S390_lowcore.jiffy_timer - xtime_cc;
                 if (tmp >= 2*CLK_TICKS_PER_JIFFY) {
                         xticks = __div(tmp, CLK_TICKS_PER_JIFFY);
@@ -212,13 +213,11 @@ void account_ticks(struct pt_regs *regs)
                         xticks = 1;
                         xtime_cc += CLK_TICKS_PER_JIFFY;
                 }
-                while (xticks--)
-                        do_timer(regs);
+                do_timer(xticks);
         }
         write_sequnlock(&xtime_lock);
 #else
-        for (xticks = ticks; xticks > 0; xticks--)
-                do_timer(regs);
+        do_timer(ticks);
 #endif
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING