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/ipv4.h

#ifndef IPV4_H
#define IPV4_H

#include <asm/byteorder.h>

#include "built_in.h"

struct ipv4hdr {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__extension__ uint8_t h_ihl:4,
			      h_version:4;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__extension__ uint8_t h_version:4,
			      h_ihl:4;
#else
# error "Please fix <asm/byteorder.h>"
#endif
	uint8_t h_tos;
	uint16_t h_tot_len;
	uint16_t h_id;
	uint16_t h_frag_off;
	uint8_t h_ttl;
	uint8_t h_protocol;
	uint16_t h_check;
	uint32_t h_saddr;
	uint32_t h_daddr;
} __packed;

#endif /* IPV4_H */