Hello Ingo, Arjan.
I'm playing with lockdep and have a question about rw-sems.
down_read_trylock() looks like
int down_read_trylock(struct rw_semaphore *sem)
{
int ret = __down_read_trylock(sem);
if (ret == 1)
rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
return ret;
}
i.e. it calls rwsem_acquire_read() with trylock == 1.
But down_write_trylock() -
int down_write_trylock(struct rw_semaphore *sem)
{
int ret = __down_write_trylock(sem);
if (ret == 1)
rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
return ret;
}
- calls lockdep with trylock set to 0. Why?
I've already caught a fake warning when trying to write-lock
an mm->mmap_sem with another mm's mmap_sem write-locked. With the
patch attached everything works, fine.
Did I miss something?
--- ./kernel/rwsem.c.pbonrem 2007-03-06 19:09:50.000000000 +0300
+++ ./kernel/rwsem.c 2007-04-06 14:02:18.000000000 +0400
@@ -60,7 +60,7 @@ int down_write_trylock(struct rw_semapho
int ret = __down_write_trylock(sem);
if (ret == 1)
- rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+ rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_);
return ret;
}
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