tracing: Fix hwlat kthread migration

The hwlat tracer creates a kernel thread at start of the tracer. It is
pinned to a single CPU and will move to the next CPU after each period of
running. If the user modifies the migration thread's affinity, it will not
change after that happens.

The original code created the thread at the first instance it was called,
but later was changed to destroy the thread after the tracer was finished,
and would not be created until the next instance of the tracer was
established. The code that initialized the affinity was only called on the
initial instantiation of the tracer. After that, it was not initialized, and
the previous affinity did not match the current newly created one, making
it appear that the user modified the thread's affinity when it did not, and
the thread failed to migrate again.

Cc: stable@vger.kernel.org
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

path: root/protos.h

#ifndef PROTOS_H
#define PROTOS_H

struct protocol;

extern struct protocol arp_ops;
extern struct protocol ethernet_ops;
extern struct protocol icmpv4_ops;
extern struct protocol icmpv6_ops;
extern struct protocol igmp_ops;
extern struct protocol ip_auth_ops;
extern struct protocol ip_esp_ops;
extern struct protocol ipv4_ops;
extern struct protocol ipv6_ops;
extern struct protocol ipv6_dest_opts_ops;
extern struct protocol ipv6_fragm_ops;
extern struct protocol ipv6_hop_by_hop_ops;
extern struct protocol ipv6_in_ipv4_ops;
extern struct protocol ipv6_mobility_ops;
extern struct protocol ipv6_no_next_header_ops;
extern struct protocol ipv6_routing_ops;
extern struct protocol lldp_ops;
extern struct protocol none_ops;
extern struct protocol tcp_ops;
extern struct protocol udp_ops;
extern struct protocol vlan_ops;
extern struct protocol ieee80211_ops;
extern struct protocol QinQ_ops;
extern struct protocol mpls_uc_ops;

#endif /* PROTOS_H */