2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Shai Fultheim <s...@scalemp.com>

commit 42fa4250436304d4650fa271f37671f6cee24e08 upstream.

On virtual environments, apic_read could take a long time. As a
result, under certain conditions the ack pending loop may exit
without any queued irqs left, but after more than one second. A
warning will be printed needlessly in this case.

If the loop is about to exit regardless of max_loops, don't
update it.

Signed-off-by: Shai Fultheim <s...@scalemp.com>
[ rebased and reworded the commit message]
Signed-off-by: Ido Yariv <i...@wizery.com>
Acked-by: Thomas Gleixner <t...@linutronix.de>
Link: http://lkml.kernel.org/r/1334873552-31346-1-git-send-email-...@wizery.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
(cherry picked from commit c9f1417be9acae3a9867f8bdab2b7924d76cf6ac)

Signed-off-by: Willy Tarreau <w...@1wt.eu>
---
 arch/x86/kernel/apic/apic.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 1d2d670..be4bf4c 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1250,11 +1250,13 @@ void __cpuinit setup_local_APIC(void)
                               acked);
                        break;
                }
-               if (cpu_has_tsc) {
-                       rdtscll(ntsc);
-                       max_loops = (cpu_khz << 10) - (ntsc - tsc);
-               } else
-                       max_loops--;
+               if (queued) {
+                       if (cpu_has_tsc) {
+                               rdtscll(ntsc);
+                               max_loops = (cpu_khz << 10) - (ntsc - tsc);
+                       } else
+                               max_loops--;
+               }
        } while (queued && max_loops > 0);
        WARN_ON(max_loops <= 0);
 
-- 
1.7.12.2.21.g234cd45.dirty



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