[PATCH -mm 2/3] lockdep: mark rwsem_acquire_read as recursive

From: Vladimir Davydov
Date: Sun Apr 06 2014 - 11:34:19 EST

rw_semaphore implementation allows recursing calls to down_read, but
lockdep thinks that it doesn't. As a result, it will complain
false-positively, e.g. if we do not observe some predefined locking
order when taking an rw semaphore for reading and a mutex.

This patch makes lockdep think rw semaphore is read-recursive, just like
rw spin lock.

Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
include/linux/lockdep.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 008388f920d7..4b95fe85375e 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -500,7 +500,7 @@ static inline void print_irqtrace_events(struct task_struct *curr)

#define rwsem_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define rwsem_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
-#define rwsem_acquire_read(l, s, t, i) lock_acquire_shared(l, s, t, NULL, i)
+#define rwsem_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
#define rwsem_release(l, n, i) lock_release(l, n, i)

#define lock_map_acquire(l) lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)

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