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/nfc/Kconfig

#
# NFC sybsystem configuration
#

menuconfig NFC
	depends on NET
	depends on RFKILL || !RFKILL
	tristate "NFC subsystem support"
	default n
	help
	  Say Y here if you want to build support for NFC (Near field
	  communication) devices.

	  To compile this support as a module, choose M here: the module will
	  be called nfc.

config NFC_DIGITAL
	depends on NFC
	select CRC_CCITT
	select CRC_ITU_T
	tristate "NFC Digital Protocol stack support"
	default n
	help
	  Say Y if you want to build NFC digital protocol stack support.
	  This is needed by NFC chipsets whose firmware only implement
	  the NFC analog layer.

	  To compile this support as a module, choose M here: the module will
	  be called nfc_digital.

source "net/nfc/nci/Kconfig"
source "net/nfc/hci/Kconfig"

source "drivers/nfc/Kconfig"