Commit 5d248bb3 authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Paul E. McKenney
Browse files

torture: Add lock_torture writer_fifo module parameter 



This commit adds a module parameter that causes the locktorture writer
to run at real-time priority.

To use it:
insmod /lib/modules/torture.ko random_shuffle=1
insmod /lib/modules/locktorture.ko torture_type=mutex_lock rt_boost=1 rt_boost_factor=50 nested_locks=3 writer_fifo=1
													^^^^^^^^^^^^^

A predecessor to this patch has been helpful to uncover issues with the
proxy-execution series.

[ paulmck: Remove locktorture-specific code from kernel/torture.c. ]

Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: kernel-team@android.com
Signed-off-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
[jstultz: Include header change to build, reword commit message]
Signed-off-by: default avatarJohn Stultz <jstultz@google.com>
Acked-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 67d5404d

Documentation/admin-guide/kernel-parameters.txt

+4 −0
Original line number Diff line number Diff line
@@ -2918,6 +2918,10 @@ 
	locktorture.torture_type= [KNL]

			Specify the locking implementation to test.



	locktorture.writer_fifo= [KNL]

			Run the write-side locktorture kthreads at

			sched_set_fifo() real-time priority.



	locktorture.verbose= [KNL]

			Enable additional printk() statements.

kernel/locking/locktorture.c

+7 −5
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable"); 
torture_param(int, rt_boost, 2,

		   "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");

torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");

torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority");

torture_param(int, verbose, 1, "Enable verbose debugging printk()s");

torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");

/* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */
@@ -809,6 +810,7 @@ static int lock_torture_writer(void *arg) 
	bool skip_main_lock;



	VERBOSE_TOROUT_STRING("lock_torture_writer task started");

	if (!rt_task(current))

		set_user_nice(current, MAX_NICE);



	do {
@@ -1015,8 +1017,7 @@ static void lock_torture_cleanup(void) 


	if (writer_tasks) {

		for (i = 0; i < cxt.nrealwriters_stress; i++)

			torture_stop_kthread(lock_torture_writer,

					     writer_tasks[i]);

			torture_stop_kthread(lock_torture_writer, writer_tasks[i]);

		kfree(writer_tasks);

		writer_tasks = NULL;

	}
@@ -1244,8 +1245,9 @@ static int __init lock_torture_init(void) 
			goto create_reader;



		/* Create writer. */

		firsterr = torture_create_kthread(lock_torture_writer, &cxt.lwsa[i],

						  writer_tasks[i]);

		firsterr = torture_create_kthread_cb(lock_torture_writer, &cxt.lwsa[i],

						     writer_tasks[i],

						     writer_fifo ? sched_set_fifo : NULL);

		if (torture_init_error(firsterr))

			goto unwind;

kernel/torture.c

+2 −1
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <linux/ktime.h>

#include <asm/byteorder.h>

#include <linux/torture.h>

#include <linux/sched/rt.h>

#include "rcu/rcu.h"



MODULE_LICENSE("GPL");
@@ -734,7 +735,7 @@ bool stutter_wait(const char *title) 
	cond_resched_tasks_rcu_qs();

	spt = READ_ONCE(stutter_pause_test);

	for (; spt; spt = READ_ONCE(stutter_pause_test)) {

		if (!ret) {

		if (!ret && !rt_task(current)) {

			sched_set_normal(current, MAX_NICE);

			ret = true;

		}