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Commitd4f200e

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fbqPeter Zijlstra
authored and
Peter Zijlstra
committed
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 candetect a read-lock/lock-write deadlock in check_noncircular(), we canstill 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 behavioron 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
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‎lib/locking-selftest.c‎

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@@ -396,6 +396,49 @@ static void rwsem_ABBA1(void)
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MU(Y1);// should fail
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}
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/*
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* read_lock(A)
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* spin_lock(B)
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*spin_lock(B)
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*write_lock(A)
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*
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* This test case is aimed at poking whether the chain cache prevents us from
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* detecting a read-lock/lock-write deadlock: if the chain cache doesn't differ
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* read/write locks, the following case may happen
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*
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* { read_lock(A)->lock(B) dependency exists }
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*
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* P0:
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* lock(B);
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* read_lock(A);
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*
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*{ Not a deadlock, B -> A is added in the chain cache }
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*
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*P1:
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*lock(B);
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*write_lock(A);
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*
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*{ B->A found in chain cache, not reported as a deadlock }
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*
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*/
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staticvoidrlock_chaincache_ABBA1(void)
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{
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RL(X1);
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L(Y1);
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U(Y1);
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RU(X1);
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L(Y1);
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RL(X1);
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RU(X1);
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U(Y1);
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L(Y1);
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WL(X1);
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WU(X1);
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U(Y1);// should fail
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}
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/*
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* read_lock(A)
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* spin_lock(B)
@@ -2062,6 +2105,10 @@ void locking_selftest(void)
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pr_cont(" |");
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dotest(rwsem_ABBA3,FAILURE,LOCKTYPE_RWSEM);
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print_testname("chain cached mixed R-L/L-W ABBA");
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pr_cont(" |");
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dotest(rlock_chaincache_ABBA1,FAILURE,LOCKTYPE_RWLOCK);
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printk(" --------------------------------------------------------------------------\n");
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/*

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