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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
This commit is contained in:
Boqun Feng 2020-08-07 15:42:32 +08:00 committed by Peter Zijlstra
parent 621c9dac0e
commit d4f200e579
1 changed files with 47 additions and 0 deletions
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47
lib/locking-selftest.c
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@ -396,6 +396,49 @@ static void rwsem_ABBA1(void)
MU(Y1); // should fail
}
/*
* 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)
@ -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");
/*