[PATCH tip/core/rcu 07/13] rcutorture: Test SRCU cleanup code path

Paul E. McKenney
2015-05-12T22:59:32Z

The current rcutorture testing does not do any cleanup operations.
This works because the srcu_struct is statically allocated, but it
does represent a memory leak of the associated dynamically allocated
->per_cpu_ref per-CPU variables. However, rcutorture currently uses
a statically allocated srcu_struct, which cannot legally be passed to
cleanup_srcu_struct(). Therefore, this commit adds a second form
of srcu (called srcud) that dynamically allocates and frees the
associated per-CPU variables. This commit also adds a ->cleanup()
member to rcu_torture_ops that is invoked at the end of the test,
after ->cb_barriers(). This ->cleanup() pointer is NULL for all
existing tests, and thus only used for scrud. Finally, the SRCU-P
torture-test configuration selects scrud instead of srcu, with SRCU-N
continuing to use srcu, thereby testing both static and dynamic
srcu_struct structures.

Reported-by: "Ahmed, Iftekhar" <ahmedi@onid.oregonstate.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/rcutorture.c | 77 ++++++++++++++++------
.../selftests/rcutorture/configs/rcu/SRCU-P.boot | 2 +-
2 files changed, 59 insertions(+), 20 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 90ff8dfc51e5..59e32684c23b 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -241,6 +241,7 @@ rcu_torture_free(struct rcu_torture *p)
struct rcu_torture_ops {
int ttype;
void (*init)(void);
+ void (*cleanup)(void);
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *rrsp);
void (*readunlock)(int idx);
@@ -477,10 +478,12 @@ static struct rcu_torture_ops rcu_busted_ops = {
*/

DEFINE_STATIC_SRCU(srcu_ctl);
+static struct srcu_struct srcu_ctld;
+static struct srcu_struct *srcu_ctlp = &srcu_ctl;

-static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
+static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
{
- return srcu_read_lock(&srcu_ctl);
+ return srcu_read_lock(srcu_ctlp);
}

static void srcu_read_delay(struct torture_random_state *rrsp)
@@ -499,49 +502,49 @@ static void srcu_read_delay(struct torture_random_state *rrsp)
rcu_read_delay(rrsp);
}

-static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
+static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
{
- srcu_read_unlock(&srcu_ctl, idx);
+ srcu_read_unlock(srcu_ctlp, idx);
}

static unsigned long srcu_torture_completed(void)
{
- return srcu_batches_completed(&srcu_ctl);
+ return srcu_batches_completed(srcu_ctlp);
}

static void srcu_torture_deferred_free(struct rcu_torture *rp)
{
- call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
+ call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
}

static void srcu_torture_synchronize(void)
{
- synchronize_srcu(&srcu_ctl);
+ synchronize_srcu(srcu_ctlp);
}

static void srcu_torture_call(struct rcu_head *head,
void (*func)(struct rcu_head *head))
{
- call_srcu(&srcu_ctl, head, func);
+ call_srcu(srcu_ctlp, head, func);
}

static void srcu_torture_barrier(void)
{
- srcu_barrier(&srcu_ctl);
+ srcu_barrier(srcu_ctlp);
}

static void srcu_torture_stats(void)
{
int cpu;
- int idx = srcu_ctl.completed & 0x1;
+ int idx = srcu_ctlp->completed & 0x1;

pr_alert("%s%s per-CPU(idx=%d):",
torture_type, TORTURE_FLAG, idx);
for_each_possible_cpu(cpu) {
long c0, c1;

- c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
- c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
+ c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
+ c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
}
pr_cont("\n");
@@ -549,7 +552,7 @@ static void srcu_torture_stats(void)

static void srcu_torture_synchronize_expedited(void)
{
- synchronize_srcu_expedited(&srcu_ctl);
+ synchronize_srcu_expedited(srcu_ctlp);
}

static struct rcu_torture_ops srcu_ops = {
@@ -569,6 +572,38 @@ static struct rcu_torture_ops srcu_ops = {
.name = "srcu"
};

+static void srcu_torture_init(void)
+{
+ rcu_sync_torture_init();
+ WARN_ON(init_srcu_struct(&srcu_ctld));
+ srcu_ctlp = &srcu_ctld;
+}
+
+static void srcu_torture_cleanup(void)
+{
+ cleanup_srcu_struct(&srcu_ctld);
+ srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
+}
+
+/* As above, but dynamically allocated. */
+static struct rcu_torture_ops srcud_ops = {
+ .ttype = SRCU_FLAVOR,
+ .init = srcu_torture_init,
+ .cleanup = srcu_torture_cleanup,
+ .readlock = srcu_torture_read_lock,
+ .read_delay = srcu_read_delay,
+ .readunlock = srcu_torture_read_unlock,
+ .started = NULL,
+ .completed = srcu_torture_completed,
+ .deferred_free = srcu_torture_deferred_free,
+ .sync = srcu_torture_synchronize,
+ .exp_sync = srcu_torture_synchronize_expedited,
+ .call = srcu_torture_call,
+ .cb_barrier = srcu_torture_barrier,
+ .stats = srcu_torture_stats,
+ .name = "srcud"
+};
+
/*
* Definitions for sched torture testing.
*/
@@ -1053,7 +1088,7 @@ static void rcu_torture_timer(unsigned long unused)
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
- srcu_read_lock_held(&srcu_ctl));
+ srcu_read_lock_held(srcu_ctlp));
if (p == NULL) {
/* Leave because rcu_torture_writer is not yet underway */
cur_ops->readunlock(idx);
@@ -1127,7 +1162,7 @@ rcu_torture_reader(void *arg)
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
- srcu_read_lock_held(&srcu_ctl));
+ srcu_read_lock_held(srcu_ctlp));
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
cur_ops->readunlock(idx);
@@ -1590,10 +1625,14 @@ rcu_torture_cleanup(void)
rcutorture_booster_cleanup(i);
}

- /* Wait for all RCU callbacks to fire. */
-
+ /*
+ * Wait for all RCU callbacks to fire, then do flavor-specific
+ * cleanup operations.
+ */
if (cur_ops->cb_barrier != NULL)
cur_ops->cb_barrier();
+ if (cur_ops->cleanup != NULL)
+ cur_ops->cleanup();

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

@@ -1670,8 +1709,8 @@ rcu_torture_init(void)
int cpu;
int firsterr = 0;
static struct rcu_torture_ops *torture_ops[] = {
- &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
- RCUTORTURE_TASKS_OPS
+ &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
+ &sched_ops, RCUTORTURE_TASKS_OPS
};

if (!torture_init_begin(torture_type, verbose, &torture_runnable))
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-P.boot b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-P.boot
index 238bfe3bd0cc..84a7d51b7481 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-P.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-P.boot
@@ -1 +1 @@
-rcutorture.torture_type=srcu
+rcutorture.torture_type=srcud
--
1.8.1.5