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/sock.h

#ifndef SOCK_H
#define SOCK_H

extern int af_socket(int af);
extern int pf_socket(void);
extern int pf_socket_type(uint32_t type);
extern void set_nonblocking(int fd);
extern int set_nonblocking_sloppy(int fd);
extern int set_reuseaddr(int fd);
extern void set_sock_qdisc_bypass(int fd, int verbose);
extern void set_sock_prio(int fd, int prio);
extern void set_tcp_nodelay(int fd);
extern void set_socket_keepalive(int fd);
extern int set_ipv6_only(int fd);
extern void set_mtu_disc_dont(int fd);
extern void set_system_socket_memory(int *vals, size_t len);
extern void reset_system_socket_memory(int *vals, size_t len);

#endif /* SOCK_H */