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authorBoqun Feng <boqun.feng@gmail.com>2020-08-07 15:42:32 +0800
committerPeter Zijlstra <peterz@infradead.org>2020-08-26 12:42:06 +0200
commitd4f200e579e96051f1f081f795820787826eb234 (patch)
treeaa3051bc538092205afceffe8c9933e4b8da7a1a /lib/locking-selftest.c
parent621c9dac0eea7607cb9a57cc9ba47fbcd4e644c9 (diff)
lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior
As our chain cache doesn't differ read/write locks, so even we can detect a read-lock/lock-write deadlock in check_noncircular(), we can still be fooled if a read-lock/lock-read case(which is not a deadlock) comes first. So introduce this test case to test specific to the chain cache behavior on detecting recursive read lock related deadlocks. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-14-boqun.feng@gmail.com
Diffstat (limited to 'lib/locking-selftest.c')
-rw-r--r--lib/locking-selftest.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index caadc4dd3368..002d1ec09852 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -400,6 +400,49 @@ static void rwsem_ABBA1(void)
* read_lock(A)
* spin_lock(B)
* spin_lock(B)
+ * write_lock(A)
+ *
+ * This test case is aimed at poking whether the chain cache prevents us from
+ * detecting a read-lock/lock-write deadlock: if the chain cache doesn't differ
+ * read/write locks, the following case may happen
+ *
+ * { read_lock(A)->lock(B) dependency exists }
+ *
+ * P0:
+ * lock(B);
+ * read_lock(A);
+ *
+ * { Not a deadlock, B -> A is added in the chain cache }
+ *
+ * P1:
+ * lock(B);
+ * write_lock(A);
+ *
+ * { B->A found in chain cache, not reported as a deadlock }
+ *
+ */
+static void rlock_chaincache_ABBA1(void)
+{
+ RL(X1);
+ L(Y1);
+ U(Y1);
+ RU(X1);
+
+ L(Y1);
+ RL(X1);
+ RU(X1);
+ U(Y1);
+
+ L(Y1);
+ WL(X1);
+ WU(X1);
+ U(Y1); // should fail
+}
+
+/*
+ * read_lock(A)
+ * spin_lock(B)
+ * spin_lock(B)
* read_lock(A)
*/
static void rlock_ABBA2(void)
@@ -2062,6 +2105,10 @@ void locking_selftest(void)
pr_cont(" |");
dotest(rwsem_ABBA3, FAILURE, LOCKTYPE_RWSEM);
+ print_testname("chain cached mixed R-L/L-W ABBA");
+ pr_cont(" |");
+ dotest(rlock_chaincache_ABBA1, FAILURE, LOCKTYPE_RWLOCK);
+
printk(" --------------------------------------------------------------------------\n");
/*