Commit d7d4102f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'scftorture.2024.11.16a' of... 

Merge tag 'scftorture.2024.11.16a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull scftorture updates from Paul McKenney:

 - Avoid divide operation

 - Fix cleanup code waiting for IPI handlers

 - Move memory allocations out of preempt-disable region of code for
   PREEMPT_RT compatibility

 - Use a lockless list to avoid freeing memory while interrupts are
   disabled, again for PREEMPT_RT compatibility

 - Make lockless list scf_add_to_free_list() correctly handle freeing a
   NULL pointer

* tag 'scftorture.2024.11.16a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  scftorture: Handle NULL argument passed to scf_add_to_free_list().
  scftorture: Use a lock-less list to free memory.
  scftorture: Move memory allocation outside of preempt_disable region.
  scftorture: Wait until scf_cleanup_handler() completes.
  scftorture: Avoid additional div operation.
parents 26c9fdd6 f946cae8

kernel/scftorture.c

+44 −10
Original line number Diff line number Diff line
@@ -97,6 +97,7 @@ struct scf_statistics { 
static struct scf_statistics *scf_stats_p;

static struct task_struct *scf_torture_stats_task;

static DEFINE_PER_CPU(long long, scf_invoked_count);

static DEFINE_PER_CPU(struct llist_head, scf_free_pool);



// Data for random primitive selection

#define SCF_PRIM_RESCHED	0
@@ -133,6 +134,7 @@ struct scf_check { 
	bool scfc_wait;

	bool scfc_rpc;

	struct completion scfc_completion;

	struct llist_node scf_node;

};



// Use to wait for all threads to start.
@@ -148,6 +150,33 @@ static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand); 


extern void resched_cpu(int cpu); // An alternative IPI vector.



static void scf_add_to_free_list(struct scf_check *scfcp)

{

	struct llist_head *pool;

	unsigned int cpu;



	if (!scfcp)

		return;

	cpu = raw_smp_processor_id() % nthreads;

	pool = &per_cpu(scf_free_pool, cpu);

	llist_add(&scfcp->scf_node, pool);

}



static void scf_cleanup_free_list(unsigned int cpu)

{

	struct llist_head *pool;

	struct llist_node *node;

	struct scf_check *scfcp;



	pool = &per_cpu(scf_free_pool, cpu);

	node = llist_del_all(pool);

	while (node) {

		scfcp = llist_entry(node, struct scf_check, scf_node);

		node = node->next;

		kfree(scfcp);

	}

}



// Print torture statistics.  Caller must ensure serialization.

static void scf_torture_stats_print(void)

{
@@ -296,7 +325,7 @@ static void scf_handler(void *scfc_in) 
		if (scfcp->scfc_rpc)

			complete(&scfcp->scfc_completion);

	} else {

		kfree(scfcp);

		scf_add_to_free_list(scfcp);

	}

}
@@ -320,10 +349,6 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
	struct scf_check *scfcp = NULL;

	struct scf_selector *scfsp = scf_sel_rand(trsp);



	if (use_cpus_read_lock)

		cpus_read_lock();

	else

		preempt_disable();

	if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {

		scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);

		if (!scfcp) {
@@ -337,6 +362,10 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
			scfcp->scfc_rpc = false;

		}

	}

	if (use_cpus_read_lock)

		cpus_read_lock();

	else

		preempt_disable();

	switch (scfsp->scfs_prim) {

	case SCF_PRIM_RESCHED:

		if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) {
@@ -363,7 +392,7 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
				scfp->n_single_wait_ofl++;

			else

				scfp->n_single_ofl++;

			kfree(scfcp);

			scf_add_to_free_list(scfcp);

			scfcp = NULL;

		}

		break;
@@ -391,7 +420,7 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
				preempt_disable();

		} else {

			scfp->n_single_rpc_ofl++;

			kfree(scfcp);

			scf_add_to_free_list(scfcp);

			scfcp = NULL;

		}

		break;
@@ -428,7 +457,7 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
			pr_warn("%s: Memory-ordering failure, scfs_prim: %d.\n", __func__, scfsp->scfs_prim);

			atomic_inc(&n_mb_out_errs); // Leak rather than trash!

		} else {

			kfree(scfcp);

			scf_add_to_free_list(scfcp);

		}

		barrier(); // Prevent race-reduction compiler optimizations.

	}
@@ -463,7 +492,7 @@ static int scftorture_invoker(void *arg) 


	// Make sure that the CPU is affinitized appropriately during testing.

	curcpu = raw_smp_processor_id();

	WARN_ONCE(curcpu != scfp->cpu % nr_cpu_ids,

	WARN_ONCE(curcpu != cpu,

		  "%s: Wanted CPU %d, running on %d, nr_cpu_ids = %d\n",

		  __func__, scfp->cpu, curcpu, nr_cpu_ids);
@@ -479,6 +508,8 @@ static int scftorture_invoker(void *arg) 
	VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);



	do {

		scf_cleanup_free_list(cpu);



		scftorture_invoke_one(scfp, &rand);

		while (cpu_is_offline(cpu) && !torture_must_stop()) {

			schedule_timeout_interruptible(HZ / 5);
@@ -523,12 +554,15 @@ static void scf_torture_cleanup(void) 
			torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);

	else

		goto end;

	smp_call_function(scf_cleanup_handler, NULL, 0);

	smp_call_function(scf_cleanup_handler, NULL, 1);

	torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);

	scf_torture_stats_print();  // -After- the stats thread is stopped!

	kfree(scf_stats_p);  // -After- the last stats print has completed!

	scf_stats_p = NULL;



	for (i = 0; i < nr_cpu_ids; i++)

		scf_cleanup_free_list(i);



	if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))

		scftorture_print_module_parms("End of test: FAILURE");

	else if (torture_onoff_failures())