mirror of
https://github.com/torvalds/linux.git
synced 2024-12-23 11:21:33 +00:00
3bd3706251
In commit:
4b53a3412d ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")
the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.
As an alternative implementation Ingo suggested to use:
struct task_struct {
const cpumask_t *cpus_ptr;
cpumask_t cpus_mask;
};
with
t->cpus_ptr = &t->cpus_mask;
In -RT we then can switch the cpus_ptr to:
t->cpus_ptr = &cpumask_of(task_cpu(p));
in a migration disabled region. The rules are simple:
- Code that 'uses' ->cpus_allowed would use the pointer.
- Code that 'modifies' ->cpus_allowed would use the direct mask.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
141 lines
2.9 KiB
C
141 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
#include <linux/module.h>
|
|
#include <linux/kthread.h>
|
|
|
|
/*
|
|
* Any file that uses trace points, must include the header.
|
|
* But only one file, must include the header by defining
|
|
* CREATE_TRACE_POINTS first. This will make the C code that
|
|
* creates the handles for the trace points.
|
|
*/
|
|
#define CREATE_TRACE_POINTS
|
|
#include "trace-events-sample.h"
|
|
|
|
static const char *random_strings[] = {
|
|
"Mother Goose",
|
|
"Snoopy",
|
|
"Gandalf",
|
|
"Frodo",
|
|
"One ring to rule them all"
|
|
};
|
|
|
|
static void simple_thread_func(int cnt)
|
|
{
|
|
int array[6];
|
|
int len = cnt % 5;
|
|
int i;
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
schedule_timeout(HZ);
|
|
|
|
for (i = 0; i < len; i++)
|
|
array[i] = i + 1;
|
|
array[i] = 0;
|
|
|
|
/* Silly tracepoints */
|
|
trace_foo_bar("hello", cnt, array, random_strings[len],
|
|
current->cpus_ptr);
|
|
|
|
trace_foo_with_template_simple("HELLO", cnt);
|
|
|
|
trace_foo_bar_with_cond("Some times print", cnt);
|
|
|
|
trace_foo_with_template_cond("prints other times", cnt);
|
|
|
|
trace_foo_with_template_print("I have to be different", cnt);
|
|
}
|
|
|
|
static int simple_thread(void *arg)
|
|
{
|
|
int cnt = 0;
|
|
|
|
while (!kthread_should_stop())
|
|
simple_thread_func(cnt++);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct task_struct *simple_tsk;
|
|
static struct task_struct *simple_tsk_fn;
|
|
|
|
static void simple_thread_func_fn(int cnt)
|
|
{
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
schedule_timeout(HZ);
|
|
|
|
/* More silly tracepoints */
|
|
trace_foo_bar_with_fn("Look at me", cnt);
|
|
trace_foo_with_template_fn("Look at me too", cnt);
|
|
}
|
|
|
|
static int simple_thread_fn(void *arg)
|
|
{
|
|
int cnt = 0;
|
|
|
|
while (!kthread_should_stop())
|
|
simple_thread_func_fn(cnt++);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static DEFINE_MUTEX(thread_mutex);
|
|
static int simple_thread_cnt;
|
|
|
|
int foo_bar_reg(void)
|
|
{
|
|
mutex_lock(&thread_mutex);
|
|
if (simple_thread_cnt++)
|
|
goto out;
|
|
|
|
pr_info("Starting thread for foo_bar_fn\n");
|
|
/*
|
|
* We shouldn't be able to start a trace when the module is
|
|
* unloading (there's other locks to prevent that). But
|
|
* for consistency sake, we still take the thread_mutex.
|
|
*/
|
|
simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
|
|
out:
|
|
mutex_unlock(&thread_mutex);
|
|
return 0;
|
|
}
|
|
|
|
void foo_bar_unreg(void)
|
|
{
|
|
mutex_lock(&thread_mutex);
|
|
if (--simple_thread_cnt)
|
|
goto out;
|
|
|
|
pr_info("Killing thread for foo_bar_fn\n");
|
|
if (simple_tsk_fn)
|
|
kthread_stop(simple_tsk_fn);
|
|
simple_tsk_fn = NULL;
|
|
out:
|
|
mutex_unlock(&thread_mutex);
|
|
}
|
|
|
|
static int __init trace_event_init(void)
|
|
{
|
|
simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
|
|
if (IS_ERR(simple_tsk))
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit trace_event_exit(void)
|
|
{
|
|
kthread_stop(simple_tsk);
|
|
mutex_lock(&thread_mutex);
|
|
if (simple_tsk_fn)
|
|
kthread_stop(simple_tsk_fn);
|
|
simple_tsk_fn = NULL;
|
|
mutex_unlock(&thread_mutex);
|
|
}
|
|
|
|
module_init(trace_event_init);
|
|
module_exit(trace_event_exit);
|
|
|
|
MODULE_AUTHOR("Steven Rostedt");
|
|
MODULE_DESCRIPTION("trace-events-sample");
|
|
MODULE_LICENSE("GPL");
|