Commit b6334320 authored by John Stultz's avatar John Stultz Committed by Paul E. McKenney
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locktorture: Add nested_[un]lock() hooks and nlocks parameter 

In order to extend locktorture to support lock nesting, add
nested_lock() and nested_unlock() hooks to the torture ops.

These take a 32bit lockset mask which is generated at random,
so some number of locks will be taken before the main lock is
taken and released afterwards.

Additionally, add nested_locks module parameter to allow
specifying the number of nested locks to be used.

This has been helpful to uncover issues in the proxy-exec
series development.

This was inspired by locktorture extensions originally implemented
by Connor O'Brien, for stress testing the proxy-execution series:
  https://lore.kernel.org/lkml/20221003214501.2050087-12-connoro@google.com/



Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Reviewed-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Co-developed-by: default avatarConnor O'Brien <connoro@google.com>
Signed-off-by: default avatarConnor O'Brien <connoro@google.com>
Signed-off-by: default avatarJohn Stultz <jstultz@google.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent fe15c26e

kernel/locking/locktorture.c

+19 −4
Original line number Diff line number Diff line
@@ -51,6 +51,9 @@ torture_param(int, rt_boost, 2, 
torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");

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 */

#define MAX_NESTED_LOCKS 8



static char *torture_type = "spin_lock";

module_param(torture_type, charp, 0444);
@@ -79,10 +82,12 @@ static void lock_torture_cleanup(void); 
struct lock_torture_ops {

	void (*init)(void);

	void (*exit)(void);

	int (*nested_lock)(int tid, u32 lockset);

	int (*writelock)(int tid);

	void (*write_delay)(struct torture_random_state *trsp);

	void (*task_boost)(struct torture_random_state *trsp);

	void (*writeunlock)(int tid);

	void (*nested_unlock)(int tid, u32 lockset);

	int (*readlock)(int tid);

	void (*read_delay)(struct torture_random_state *trsp);

	void (*readunlock)(int tid);
@@ -684,6 +689,7 @@ static int lock_torture_writer(void *arg) 
	struct lock_stress_stats *lwsp = arg;

	int tid = lwsp - cxt.lwsa;

	DEFINE_TORTURE_RANDOM(rand);

	u32 lockset_mask;



	VERBOSE_TOROUT_STRING("lock_torture_writer task started");

	set_user_nice(current, MAX_NICE);
@@ -692,7 +698,10 @@ static int lock_torture_writer(void *arg) 
		if ((torture_random(&rand) & 0xfffff) == 0)

			schedule_timeout_uninterruptible(1);



		lockset_mask = torture_random(&rand);

		cxt.cur_ops->task_boost(&rand);

		if (cxt.cur_ops->nested_lock)

			cxt.cur_ops->nested_lock(tid, lockset_mask);

		cxt.cur_ops->writelock(tid);

		if (WARN_ON_ONCE(lock_is_write_held))

			lwsp->n_lock_fail++;
@@ -705,6 +714,8 @@ static int lock_torture_writer(void *arg) 
		lock_is_write_held = false;

		WRITE_ONCE(last_lock_release, jiffies);

		cxt.cur_ops->writeunlock(tid);

		if (cxt.cur_ops->nested_unlock)

			cxt.cur_ops->nested_unlock(tid, lockset_mask);



		stutter_wait("lock_torture_writer");

	} while (!torture_must_stop());
@@ -845,11 +856,11 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops, 
				const char *tag)

{

	pr_alert("%s" TORTURE_FLAG

		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",

		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",

		 torture_type, tag, cxt.debug_lock ? " [debug]": "",

		 cxt.nrealwriters_stress, cxt.nrealreaders_stress, stat_interval,

		 verbose, shuffle_interval, stutter, shutdown_secs,

		 onoff_interval, onoff_holdoff);

		 cxt.nrealwriters_stress, cxt.nrealreaders_stress,

		 nested_locks, stat_interval, verbose, shuffle_interval,

		 stutter, shutdown_secs, onoff_interval, onoff_holdoff);

}



static void lock_torture_cleanup(void)
@@ -1068,6 +1079,10 @@ static int __init lock_torture_init(void) 
		}

	}



	/* cap nested_locks to MAX_NESTED_LOCKS */

	if (nested_locks > MAX_NESTED_LOCKS)

		nested_locks = MAX_NESTED_LOCKS;



	if (cxt.cur_ops->readlock) {

		reader_tasks = kcalloc(cxt.nrealreaders_stress,

				       sizeof(reader_tasks[0]),