Commit 34e8c483 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

scftorture: Add smp_call_function() memory-ordering checks 



This commit adds checks for memory misordering across calls to and
returns from smp_call_function() 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 980205ee

kernel/scftorture.c

+17 −8
Original line number Diff line number Diff line
@@ -297,11 +297,13 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
		cpus_read_lock();

	else

		preempt_disable();

	switch (scfsp->scfs_prim) {

	case SCF_PRIM_SINGLE:

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

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

		if (WARN_ON_ONCE(!scfcp))

			atomic_inc(&n_alloc_errs);

	}

	switch (scfsp->scfs_prim) {

	case SCF_PRIM_SINGLE:

		cpu = torture_random(trsp) % nr_cpu_ids;

		if (scfsp->scfs_wait)

			scfp->n_single_wait++;
@@ -328,11 +330,6 @@ 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
@@ -356,7 +353,19 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra 
			scfp->n_all_wait++;

		else

			scfp->n_all++;

		smp_call_function(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(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;

	}

	if (use_cpus_read_lock)

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