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Subject[PATCH 4.15 005/146] IB/uverbs: Improve lockdep_check
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Gunthorpe <jgg@mellanox.com>

commit 104f268d439b3c21c83708e52946a4d8d37f3d0f upstream.

This is really being used as an assert that the expected usecnt
is being held and implicitly that the usecnt is valid. Rename it to
assert_uverbs_usecnt and tighten the checks to only accept valid
values of usecnt (eg 0 and < -1 are invalid).

The tigher checkes make the assertion cover more cases and is more
likely to find bugs via syzkaller/etc.

Fixes: 3832125624b7 ("IB/core: Add support for idr types")
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/core/rdma_core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -407,13 +407,13 @@ static int __must_check remove_commit_fd
return ret;
}

-static void lockdep_check(struct ib_uobject *uobj, bool exclusive)
+static void assert_uverbs_usecnt(struct ib_uobject *uobj, bool exclusive)
{
#ifdef CONFIG_LOCKDEP
if (exclusive)
- WARN_ON(atomic_read(&uobj->usecnt) > 0);
+ WARN_ON(atomic_read(&uobj->usecnt) != -1);
else
- WARN_ON(atomic_read(&uobj->usecnt) == -1);
+ WARN_ON(atomic_read(&uobj->usecnt) <= 0);
#endif
}

@@ -452,7 +452,7 @@ int __must_check rdma_remove_commit_uobj
WARN(true, "ib_uverbs: Cleanup is running while removing an uobject\n");
return 0;
}
- lockdep_check(uobj, true);
+ assert_uverbs_usecnt(uobj, true);
ret = _rdma_remove_commit_uobject(uobj, RDMA_REMOVE_DESTROY);

up_read(&ucontext->cleanup_rwsem);
@@ -482,7 +482,7 @@ int rdma_explicit_destroy(struct ib_uobj
WARN(true, "ib_uverbs: Cleanup is running while removing an uobject\n");
return 0;
}
- lockdep_check(uobject, true);
+ assert_uverbs_usecnt(uobject, true);
ret = uobject->type->type_class->remove_commit(uobject,
RDMA_REMOVE_DESTROY);
if (ret)
@@ -569,7 +569,7 @@ static void lookup_put_fd_uobject(struct

void rdma_lookup_put_uobject(struct ib_uobject *uobj, bool exclusive)
{
- lockdep_check(uobj, exclusive);
+ assert_uverbs_usecnt(uobj, exclusive);
uobj->type->type_class->lookup_put(uobj, exclusive);
/*
* In order to unlock an object, either decrease its usecnt for

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