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Date: Wed, 6 Sep 2017 16:28:18 +0800 From: Boqun Feng <boqun.feng@...il.com> To: linux-kernel@...r.kernel.org Cc: Ingo Molnar <mingo@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Gautham R Shenoy <ego@...ux.vnet.ibm.com>, Byungchul Park <byungchul.park@....com>, Boqun Feng <boqun.feng@...il.com> Subject: [RFC tip/locking v2 07/13] lockdep: Support deadlock detection for recursive read in check_noncircular() Currently, lockdep only has limit support for deadlock detection for recursive read locks. The basic idea of the detection is: Since we make __bfs() able to traverse only the strong dependency paths, so we report a circular deadlock if we could find a circle of a strong dependency path. Signed-off-by: Boqun Feng <boqun.feng@...il.com> --- kernel/locking/lockdep.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index d9959f25247a..8a09b1a02342 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1345,6 +1345,14 @@ static inline int hlock_equal(struct lock_list *entry, void *data) (hlock->read == 2 || !entry->is_rr); } +static inline int hlock_conflict(struct lock_list *entry, void *data) +{ + struct held_lock *hlock = (struct held_lock *)data; + + return hlock_class(hlock) == entry->class && + (hlock->read != 2 || !entry->is_rr); +} + static noinline int print_circular_bug(struct lock_list *this, struct lock_list *target, struct held_lock *check_src, @@ -1459,18 +1467,18 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) } /* - * Prove that the dependency graph starting at <entry> can not + * Prove that the dependency graph starting at <root> can not * lead to <target>. Print an error and return BFS_RMATCH if it does. */ static noinline enum bfs_result -check_noncircular(struct lock_list *root, struct lock_class *target, +check_noncircular(struct lock_list *root, struct held_lock *target, struct lock_list **target_entry) { enum bfs_result result; debug_atomic_inc(nr_cyclic_checks); - result = __bfs_forwards(root, target, class_equal, target_entry); + result = __bfs_forwards(root, target, hlock_conflict, target_entry); return result; } -- 2.14.1
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