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/tools/perf/ui/ui.h

#ifndef _PERF_UI_H_
#define _PERF_UI_H_ 1

#include <pthread.h>
#include <stdbool.h>
#include <linux/compiler.h>

extern pthread_mutex_t ui__lock;
extern void *perf_gtk_handle;

extern int use_browser;

void setup_browser(bool fallback_to_pager);
void exit_browser(bool wait_for_ok);

#ifdef HAVE_SLANG_SUPPORT
int ui__init(void);
void ui__exit(bool wait_for_ok);
#else
static inline int ui__init(void)
{
	return -1;
}
static inline void ui__exit(bool wait_for_ok __maybe_unused) {}
#endif

void ui__refresh_dimensions(bool force);

struct option;

int stdio__config_color(const struct option *opt, const char *mode, int unset);

#endif /* _PERF_UI_H_ */