x86/mce: Make timer handling more robust

Erik reported that on a preproduction hardware a CMCI storm triggers the
BUG_ON in add_timer_on(). The reason is that the per CPU MCE timer is
started by the CMCI logic before the MCE CPU hotplug callback starts the
timer with add_timer_on(). So the timer is already queued which triggers
the BUG.

Using add_timer_on() is pretty pointless in this code because the timer is
strictlty per CPU, initialized as pinned and all operations which arm the
timer happen on the CPU to which the timer belongs.

Simplify the whole machinery by using mod_timer() instead of add_timer_on()
which avoids the problem because mod_timer() can handle already queued
timers. Use __start_timer() everywhere so the earliest armed expiry time is
preserved.

Reported-by: Erik Veijola <erik.veijola@intel.com>
Tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701310936080.3457@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

path: root/net/iucv/Kconfig

config IUCV
	depends on S390
	def_tristate y if S390
	prompt "IUCV support (S390 - z/VM only)"
	help
	  Select this option if you want to use inter-user communication
	  under VM or VIF. If you run on z/VM, say "Y" to enable a fast
	  communication link between VM guests.

config AFIUCV
	depends on S390
	def_tristate m if QETH_L3 || IUCV
	prompt "AF_IUCV Socket support (S390 - z/VM and HiperSockets transport)"
	help
	  Select this option if you want to use AF_IUCV socket applications
	  based on z/VM inter-user communication vehicle or based on
	  HiperSockets.