Commit 980205ee authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

scftorture: Add smp_call_function_many() memory-ordering checks 



This commit adds checks for memory misordering across calls to and
returns from smp_call_function_many() in the case where the caller waits.
Misordering results in a splat.

Note that in contrast to smp_call_function_single(), this code does not
test memory ordering into the handler in the no-wait case because none
of the handlers would be able to free the scf_check structure without
introducing heavy synchronization to work out which was last.

[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent b93e21a5

kernel/scftorture.c

+23 −3
Original line number Diff line number Diff line
@@ -240,8 +240,11 @@ static void scf_handler(void *scfc_in) 
	unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));

	struct scf_check *scfcp = scfc_in;



	if (likely(scfcp) && WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))

	if (likely(scfcp)) {

		WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.

		if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))

			atomic_inc(&n_mb_in_errs);

	}

	this_cpu_inc(scf_invoked_count);

	if (longwait <= 0) {

		if (!(r & 0xffc0))
@@ -325,11 +328,28 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
		}

		break;

	case SCF_PRIM_MANY:

		if (scfsp->scfs_wait) {

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

			if (WARN_ON_ONCE(!scfcp))

				atomic_inc(&n_alloc_errs);

		}

		if (scfsp->scfs_wait)

			scfp->n_many_wait++;

		else

			scfp->n_many++;

		smp_call_function_many(cpu_online_mask, scf_handler, NULL, scfsp->scfs_wait);

		if (scfcp) {

			scfcp->scfc_cpu = -1;

			scfcp->scfc_wait = true;

			scfcp->scfc_out = false;

			scfcp->scfc_in = true;

		}

		smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);

		if (scfcp) {

			if (WARN_ON_ONCE(!scfcp->scfc_out))

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

			else

				kfree(scfcp);

		}

		break;

	case SCF_PRIM_ALL:

		if (scfsp->scfs_wait)

CRA Git | Maintained and supported by SUSTech CRA and CCSE