idr test suite: Create anchor before launching throbber

BugLink: https://bugs.launchpad.net/bugs/1926993
[ Upstream commit 094ffbd1d8eaa27ed426feb8530cb1456348b018 ]

The throbber could race with creation of the anchor entry and cause the
IDR to have zero entries in it, which would cause the test to fail.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
index 4a9b451b7ba031b2dab8ec7cd985f3fdb52144eb..6ce7460f3c7a9caf60da686f22693bd2ebba0346 100644 (file)
--- a/tools/testing/radix-tree/idr-test.c
+++ b/tools/testing/radix-tree/idr-test.c
@@ -301,11 +301,11 @@ void idr_find_test_1(int anchor_id, int throbber_id)
        pthread_t throbber;
        time_t start = time(NULL);
 
-       pthread_create(&throbber, NULL, idr_throbber, &throbber_id);
-
        BUG_ON(idr_alloc(&find_idr, xa_mk_value(anchor_id), anchor_id,
                                anchor_id + 1, GFP_KERNEL) != anchor_id);
 
+       pthread_create(&throbber, NULL, idr_throbber, &throbber_id);
+
        rcu_read_lock();
        do {
                int id = 0;