Re: [PATCH tip/core/rcu 37/55] rcutorture: Abstract torture_create_kthread()

[Josh Triplett <josh@joshtriplett.org>]

On Mon, Feb 17, 2014 at 02:12:41PM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> 
> Creation of kthreads is not RCU-specific, so this commit abstracts
> out torture_create_kthread(), saving a few tens of lines of code in
> the process.
> 
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

One comment below.

>  include/linux/torture.h |  8 +++-
>  kernel/rcu/rcutorture.c | 98 ++++++++++---------------------------------------
>  kernel/torture.c        | 80 +++++++++++++++++-----------------------
>  3 files changed, 60 insertions(+), 126 deletions(-)
> 
> diff --git a/include/linux/torture.h b/include/linux/torture.h
> index db9bc7756a32..e5264c6ecfeb 100644
> --- a/include/linux/torture.h
> +++ b/include/linux/torture.h
> @@ -47,7 +47,7 @@
>  #define VERBOSE_TOROUT_STRING(s) \
>  	do { if (verbose) pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s); } while (0)
>  #define VERBOSE_TOROUT_ERRSTRING(s) \
> -	do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
> +	do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! %s\n", torture_type, s); } while (0)

This change is also unrelated, and should not occur in this commit.

- Josh Triplett

>  /* Definitions for a non-string torture-test module parameter. */
>  #define torture_parm(type, name, init, msg) \
> @@ -89,5 +89,11 @@ bool torture_cleanup(void);
>  bool torture_must_stop(void);
>  bool torture_must_stop_irq(void);
>  void torture_kthread_stopping(char *title);
> +int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
> +			     char *f, struct task_struct **tp);
> +
> +#define torture_create_kthread(n, arg, tp) \
> +	_torture_create_kthread(n, (arg), #n, "Creating " #n " task", \
> +				"Failed to create " #n, &(tp))
>  
>  #endif /* __LINUX_TORTURE_H */
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index cf365160b44f..951a5559d9fa 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -1104,19 +1104,9 @@ static int rcu_torture_stall(void *args)
>  /* Spawn CPU-stall kthread, if stall_cpu specified. */
>  static int __init rcu_torture_stall_init(void)
>  {
> -	int ret;
> -
>  	if (stall_cpu <= 0)
>  		return 0;
> -	VERBOSE_TOROUT_STRING("Creating rcu_torture_stall task");
> -	stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
> -	if (IS_ERR(stall_task)) {
> -		ret = PTR_ERR(stall_task);
> -		stall_task = NULL;
> -		return ret;
> -	}
> -	torture_shuffle_task_register(stall_task);
> -	return 0;
> +	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
>  }
>  
>  /* Clean up after the CPU-stall kthread, if one was spawned. */
> @@ -1225,29 +1215,13 @@ static int rcu_torture_barrier_init(void)
>  		return -ENOMEM;
>  	for (i = 0; i < n_barrier_cbs; i++) {
>  		init_waitqueue_head(&barrier_cbs_wq[i]);
> -		VERBOSE_TOROUT_STRING("Creating rcu_torture_barrier_cbs task");
> -		barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
> -						   (void *)(long)i,
> -						   "rcu_torture_barrier_cbs");
> -		if (IS_ERR(barrier_cbs_tasks[i])) {
> -			ret = PTR_ERR(barrier_cbs_tasks[i]);
> -			VERBOSE_TOROUT_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
> -			barrier_cbs_tasks[i] = NULL;
> +		ret = torture_create_kthread(rcu_torture_barrier_cbs,
> +					     (void *)(long)i,
> +					     barrier_cbs_tasks[i]);
> +		if (ret)
>  			return ret;
> -		}
> -		torture_shuffle_task_register(barrier_cbs_tasks[i]);
>  	}
> -	VERBOSE_TOROUT_STRING("Creating rcu_torture_barrier task");
> -	barrier_task = kthread_run(rcu_torture_barrier, NULL,
> -				   "rcu_torture_barrier");
> -	if (IS_ERR(barrier_task)) {
> -		ret = PTR_ERR(barrier_task);
> -		VERBOSE_TOROUT_ERRSTRING("Failed to create rcu_torture_barrier");
> -		barrier_task = NULL;
> -		return ret;
> -	}
> -	torture_shuffle_task_register(barrier_task);
> -	return 0;
> +	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
>  }
>  
>  /* Clean up after RCU barrier testing. */
> @@ -1515,17 +1489,10 @@ rcu_torture_init(void)
>  
>  	/* Start up the kthreads. */
>  
> -	VERBOSE_TOROUT_STRING("Creating rcu_torture_writer task");
> -	writer_task = kthread_create(rcu_torture_writer, NULL,
> -				     "rcu_torture_writer");
> -	if (IS_ERR(writer_task)) {
> -		firsterr = PTR_ERR(writer_task);
> -		VERBOSE_TOROUT_ERRSTRING("Failed to create writer");
> -		writer_task = NULL;
> +	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
> +					  writer_task);
> +	if (firsterr)
>  		goto unwind;
> -	}
> -	torture_shuffle_task_register(writer_task);
> -	wake_up_process(writer_task);
>  	fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
>  				   GFP_KERNEL);
>  	if (fakewriter_tasks == NULL) {
> @@ -1534,16 +1501,10 @@ rcu_torture_init(void)
>  		goto unwind;
>  	}
>  	for (i = 0; i < nfakewriters; i++) {
> -		VERBOSE_TOROUT_STRING("Creating rcu_torture_fakewriter task");
> -		fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
> -						  "rcu_torture_fakewriter");
> -		if (IS_ERR(fakewriter_tasks[i])) {
> -			firsterr = PTR_ERR(fakewriter_tasks[i]);
> -			VERBOSE_TOROUT_ERRSTRING("Failed to create fakewriter");
> -			fakewriter_tasks[i] = NULL;
> +		firsterr = torture_create_kthread(rcu_torture_fakewriter,
> +						  NULL, fakewriter_tasks[i]);
> +		if (firsterr)
>  			goto unwind;
> -		}
> -		torture_shuffle_task_register(fakewriter_tasks[i]);
>  	}
>  	reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
>  			       GFP_KERNEL);
> @@ -1553,28 +1514,16 @@ rcu_torture_init(void)
>  		goto unwind;
>  	}
>  	for (i = 0; i < nrealreaders; i++) {
> -		VERBOSE_TOROUT_STRING("Creating rcu_torture_reader task");
> -		reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
> -					      "rcu_torture_reader");
> -		if (IS_ERR(reader_tasks[i])) {
> -			firsterr = PTR_ERR(reader_tasks[i]);
> -			VERBOSE_TOROUT_ERRSTRING("Failed to create reader");
> -			reader_tasks[i] = NULL;
> +		firsterr = torture_create_kthread(rcu_torture_reader, NULL,
> +						  reader_tasks[i]);
> +		if (firsterr)
>  			goto unwind;
> -		}
> -		torture_shuffle_task_register(reader_tasks[i]);
>  	}
>  	if (stat_interval > 0) {
> -		VERBOSE_TOROUT_STRING("Creating rcu_torture_stats task");
> -		stats_task = kthread_run(rcu_torture_stats, NULL,
> -					"rcu_torture_stats");
> -		if (IS_ERR(stats_task)) {
> -			firsterr = PTR_ERR(stats_task);
> -			VERBOSE_TOROUT_ERRSTRING("Failed to create stats");
> -			stats_task = NULL;
> +		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
> +						  stats_task);
> +		if (firsterr)
>  			goto unwind;
> -		}
> -		torture_shuffle_task_register(stats_task);
>  	}
>  	if (test_no_idle_hz) {
>  		firsterr = torture_shuffle_init(shuffle_interval * HZ);
> @@ -1592,16 +1541,9 @@ rcu_torture_init(void)
>  		fqs_duration = 0;
>  	if (fqs_duration) {
>  		/* Create the fqs thread */
> -		VERBOSE_TOROUT_STRING("Creating rcu_torture_fqs task");
> -		fqs_task = kthread_run(rcu_torture_fqs, NULL,
> -				       "rcu_torture_fqs");
> -		if (IS_ERR(fqs_task)) {
> -			firsterr = PTR_ERR(fqs_task);
> -			VERBOSE_TOROUT_ERRSTRING("Failed to create fqs");
> -			fqs_task = NULL;
> +		torture_create_kthread(rcu_torture_fqs, NULL, fqs_task);
> +		if (firsterr)
>  			goto unwind;
> -		}
> -		torture_shuffle_task_register(fqs_task);
>  	}
>  	if (test_boost_interval < 1)
>  		test_boost_interval = 1;
> diff --git a/kernel/torture.c b/kernel/torture.c
> index 6f1c6600d183..94760f0f2923 100644
> --- a/kernel/torture.c
> +++ b/kernel/torture.c
> @@ -180,23 +180,16 @@ torture_onoff(void *arg)
>   */
>  int torture_onoff_init(long ooholdoff, long oointerval)
>  {
> -#ifdef CONFIG_HOTPLUG_CPU
> -	int ret;
> +	int ret = 0;
>  
> +#ifdef CONFIG_HOTPLUG_CPU
>  	onoff_holdoff = ooholdoff;
>  	onoff_interval = oointerval;
>  	if (onoff_interval <= 0)
>  		return 0;
> -	VERBOSE_TOROUT_STRING("Creating torture_onoff task");
> -	onoff_task = kthread_run(torture_onoff, NULL, "torture_onoff");
> -	if (IS_ERR(onoff_task)) {
> -		ret = PTR_ERR(onoff_task);
> -		onoff_task = NULL;
> -		return ret;
> -	}
> -	torture_shuffle_task_register(onoff_task);
> +	ret = torture_create_kthread(torture_onoff, NULL, onoff_task);
>  #endif /* #ifdef CONFIG_HOTPLUG_CPU */
> -	return 0;
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(torture_onoff_init);
>  
> @@ -379,8 +372,6 @@ static int torture_shuffle(void *arg)
>   */
>  int torture_shuffle_init(long shuffint)
>  {
> -	int ret;
> -
>  	shuffle_interval = shuffint;
>  
>  	shuffle_idle_cpu = -1;
> @@ -391,17 +382,7 @@ int torture_shuffle_init(long shuffint)
>  	}
>  
>  	/* Create the shuffler thread */
> -	VERBOSE_TOROUT_STRING("Creating torture_shuffle task");
> -	shuffler_task = kthread_run(torture_shuffle, NULL, "torture_shuffle");
> -	if (IS_ERR(shuffler_task)) {
> -		ret = PTR_ERR(shuffler_task);
> -		free_cpumask_var(shuffle_tmp_mask);
> -		VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
> -		shuffler_task = NULL;
> -		return ret;
> -	}
> -	torture_shuffle_task_register(shuffler_task);
> -	return 0;
> +	return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
>  }
>  EXPORT_SYMBOL_GPL(torture_shuffle_init);
>  
> @@ -483,25 +464,16 @@ static int torture_shutdown(void *arg)
>   */
>  int torture_shutdown_init(int ssecs, void (*cleanup)(void))
>  {
> -	int ret;
> +	int ret = 0;
>  
>  	shutdown_secs = ssecs;
>  	torture_shutdown_hook = cleanup;
>  	if (shutdown_secs > 0) {
> -		VERBOSE_TOROUT_STRING("Creating torture_shutdown task");
>  		shutdown_time = jiffies + shutdown_secs * HZ;
> -		shutdown_task = kthread_create(torture_shutdown, NULL,
> -					       "torture_shutdown");
> -		if (IS_ERR(shutdown_task)) {
> -			ret = PTR_ERR(shutdown_task);
> -			VERBOSE_TOROUT_ERRSTRING("Failed to create shutdown");
> -			shutdown_task = NULL;
> -			return ret;
> -		}
> -		torture_shuffle_task_register(shutdown_task);
> -		wake_up_process(shutdown_task);
> +		ret = torture_create_kthread(torture_shutdown, NULL,
> +					     shutdown_task);
>  	}
> -	return 0;
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(torture_shutdown_init);
>  
> @@ -595,16 +567,8 @@ int torture_stutter_init(int s)
>  	int ret;
>  
>  	stutter = s;
> -	VERBOSE_TOROUT_STRING("Creating torture_stutter task");
> -	stutter_task = kthread_run(torture_stutter, NULL, "torture_stutter");
> -	if (IS_ERR(stutter_task)) {
> -		ret = PTR_ERR(stutter_task);
> -		VERBOSE_TOROUT_ERRSTRING("Failed to create stutter");
> -		stutter_task = NULL;
> -		return ret;
> -	}
> -	torture_shuffle_task_register(stutter_task);
> -	return 0;
> +	ret = torture_create_kthread(torture_stutter, NULL, stutter_task);
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(torture_stutter_init);
>  
> @@ -714,3 +678,25 @@ void torture_kthread_stopping(char *title)
>  	}
>  }
>  EXPORT_SYMBOL_GPL(torture_kthread_stopping);
> +
> +/*
> + * Create a generic torture kthread that is immediately runnable.  If you
> + * need the kthread to be stopped so that you can do something to it before
> + * it starts, you will need to open-code your own.
> + */
> +int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
> +			    char *f, struct task_struct **tp)
> +{
> +	int ret = 0;
> +
> +	VERBOSE_TOROUT_STRING(m);
> +	*tp = kthread_run(fn, arg, s);
> +	if (IS_ERR(*tp)) {
> +		ret = PTR_ERR(*tp);
> +		VERBOSE_TOROUT_ERRSTRING(f);
> +		*tp = NULL;
> +	}
> +	torture_shuffle_task_register(*tp);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(_torture_create_kthread);
> -- 
> 1.8.1.5
>