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/net/ipcomp.h

#ifndef _NET_IPCOMP_H
#define _NET_IPCOMP_H

#include <linux/types.h>

#define IPCOMP_SCRATCH_SIZE     65400

struct crypto_comp;

struct ipcomp_data {
	u16 threshold;
	struct crypto_comp * __percpu *tfms;
};

struct ip_comp_hdr;
struct sk_buff;
struct xfrm_state;

int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb);
int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb);
void ipcomp_destroy(struct xfrm_state *x);
int ipcomp_init_state(struct xfrm_state *x);

static inline struct ip_comp_hdr *ip_comp_hdr(const struct sk_buff *skb)
{
	return (struct ip_comp_hdr *)skb_transport_header(skb);
}

#endif