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/net/6lowpan/nhc_dest.c

/*
 *	6LoWPAN IPv6 Destination Options Header compression according to
 *	RFC6282
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#include "nhc.h"

#define LOWPAN_NHC_DEST_IDLEN	1
#define LOWPAN_NHC_DEST_ID_0	0xe6
#define LOWPAN_NHC_DEST_MASK_0	0xfe

static void dest_nhid_setup(struct lowpan_nhc *nhc)
{
	nhc->id[0] = LOWPAN_NHC_DEST_ID_0;
	nhc->idmask[0] = LOWPAN_NHC_DEST_MASK_0;
}

LOWPAN_NHC(nhc_dest, "RFC6282 Destination Options", NEXTHDR_DEST, 0,
	   dest_nhid_setup, LOWPAN_NHC_DEST_IDLEN, NULL, NULL);

module_lowpan_nhc(nhc_dest);
MODULE_DESCRIPTION("6LoWPAN next header RFC6282 Destination Options compression");
MODULE_LICENSE("GPL");