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/include/acpi/acpi_io.h

#ifndef _ACPI_IO_H_
#define _ACPI_IO_H_

#include <linux/io.h>

#include <asm/acpi.h>

#ifndef acpi_os_ioremap
static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
					    acpi_size size)
{
       return ioremap_cache(phys, size);
}
#endif

extern bool acpi_permanent_mmap;

void __iomem *__ref
acpi_os_map_iomem(acpi_physical_address phys, acpi_size size);
void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size);
void __iomem *acpi_os_get_iomem(acpi_physical_address phys, unsigned int size);

int acpi_os_map_generic_address(struct acpi_generic_address *addr);
void acpi_os_unmap_generic_address(struct acpi_generic_address *addr);

#endif