releases/2.6.32.17/fix-spinaphore-down_spin.patch

   1 From b70f4e85bfc4d7000036355b714a92d5c574f1be Mon Sep 17 00:00:00 2001
   2 From: Tony Luck <tony.luck@intel.com>
   3 Date: Wed, 30 Jun 2010 10:46:16 -0700
   4 Subject: [IA64] Fix spinaphore down_spin()
   5
   6 From: Tony Luck <tony.luck@intel.com>
   7
   8 commit b70f4e85bfc4d7000036355b714a92d5c574f1be upstream.
   9
  10 Typo in down_spin() meant it only read the low 32 bits of the
  11 "serve" value, instead of the full 64 bits. This results in the
  12 system hanging when the values in ticket/serve get larger than
  13 32-bits. A big enough system running the right test can hit this
  14 in a just a few hours.
  15
  16 Broken since 883a3acf5b0d4782ac35981227a0d094e8b44850
  17     [IA64] Re-implement spinaphores using ticket lock concepts
  18
  19 Reported via IRC by Bjorn Helgaas
  20
  21 Signed-off-by: Tony Luck <tony.luck@intel.com>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  23
  24 ---
  25  arch/ia64/mm/tlb.c |    2 +-
  26  1 file changed, 1 insertion(+), 1 deletion(-)
  27
  28 --- a/arch/ia64/mm/tlb.c
  29 +++ b/arch/ia64/mm/tlb.c
  30 @@ -120,7 +120,7 @@ static inline void down_spin(struct spin
  31         ia64_invala();
  32
  33         for (;;) {
  34 -               asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
  35 +               asm volatile ("ld8.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
  36                 if (time_before(t, serve))
  37                         return;
  38                 cpu_relax();