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From: Greg KH on 30 Jul 2010 14:10
2.6.34-stable review patch. If anyone has any objections, please let us know.

------------------

From: Tony Luck <tony.luck(a)intel.com>

commit b70f4e85bfc4d7000036355b714a92d5c574f1be upstream.

Typo in down_spin() meant it only read the low 32 bits of the
"serve" value, instead of the full 64 bits. This results in the
system hanging when the values in ticket/serve get larger than
32-bits. A big enough system running the right test can hit this
in a just a few hours.

Broken since 883a3acf5b0d4782ac35981227a0d094e8b44850
[IA64] Re-implement spinaphores using ticket lock concepts

Reported via IRC by Bjorn Helgaas

Signed-off-by: Tony Luck <tony.luck(a)intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
arch/ia64/mm/tlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -121,7 +121,7 @@ static inline void down_spin(struct spin
ia64_invala();

for (;;) {
- asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
+ asm volatile ("ld8.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
if (time_before(t, serve))
return;
cpu_relax();


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