[PATCH AUTOSEL 5.10 16/22] idr test suite: Take RCU read lock in idr_find_test_1

Sasha Levin
2021-04-05T16:06:08Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

[ Upstream commit 703586410da69eb40062e64d413ca33bd735917a ]

When run on a single CPU, this test would frequently access already-freed
memory. Due to timing, this bug never showed up on multi-CPU tests.

Reported-by: Chris von Recklinghausen <crecklin@redhat.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/radix-tree/idr-test.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
index 44ceff95a9b3..4a9b451b7ba0 100644
--- a/tools/testing/radix-tree/idr-test.c
+++ b/tools/testing/radix-tree/idr-test.c
@@ -306,11 +306,15 @@ void idr_find_test_1(int anchor_id, int throbber_id)
BUG_ON(idr_alloc(&find_idr, xa_mk_value(anchor_id), anchor_id,
anchor_id + 1, GFP_KERNEL) != anchor_id);

+ rcu_read_lock();
do {
int id = 0;
void *entry = idr_get_next(&find_idr, &id);
+ rcu_read_unlock();
BUG_ON(entry != xa_mk_value(id));
+ rcu_read_lock();
} while (time(NULL) < start + 11);
+ rcu_read_unlock();

pthread_join(throbber, NULL);

--
2.30.2