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authorPaul E. McKenney <paulmck@kernel.org>2020-07-01 12:30:02 -0700
committerPaul E. McKenney <paulmck@kernel.org>2020-08-24 18:38:34 -0700
commit980205ee8489d53c4380f7762debac87312b0fb3 (patch)
tree5788b2b43ca6e0a9fb7a5ece6dcd197bd8319990 /kernel/scftorture.c
parentb93e21a51e1c8ed3816da888d34f88193ad1b917 (diff)
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: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/scftorture.c')
-rw-r--r--kernel/scftorture.c26
1 files changed, 23 insertions, 3 deletions
diff --git a/kernel/scftorture.c b/kernel/scftorture.c
index 9b42271d64f1..3519ad1b3278 100644
--- a/kernel/scftorture.c
+++ b/kernel/scftorture.c
@@ -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))))
- atomic_inc(&n_mb_in_errs);
+ 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)