tree be96c432f97e0390d615acf0a162671705d6570e
parent c0758146adbe39514e75ac860ce7e49f865c2297
author Bryan Sutula <Bryan.Sutula@hp.com> 1128531726 -0600
committer Tony Luck <tony.luck@intel.com> 1128636251 -0700

[IA64] Avoid kernel hang during CMC interrupt storm

I've noticed a kernel hang during a storm of CMC interrupts, which was
tracked down to the continual execution of the interrupt handler.

There's code in the CMC handler that's supposed to disable CMC
interrupts and switch to polling mode when it sees a bunch of CMCs.
Because disabling CMCs across all CPUs isn't safe in interrupt context,
the disable is done with a schedule_work().  But with continual CMC
interrupts, the schedule_work() never gets executed.

The following patch immediately disables CMC interrupts for the current
CPU.  This then allows (at least) one CPU to ignore CMC interrupts,
execute the schedule_work() code, and disable CMC interrupts on the rest
of the CPUs.

Acked-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Bryan Sutula <Bryan.Sutula@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>