From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
This clarifies the design intention that time between allocate and
commit has the uobj exclusive to the caller. We already guarantee
this by delaying publishing the uobj pointer via idr_insert,
fd_install, list_add, etc.
Additionally holding the usecnt lock during this period provides
extra clarity and more protection against future mistakes.
Fixes: 3832125624b7 ("IB/core: Add support for idr types")
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
---
drivers/infiniband/core/rdma_core.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
index 85b5ee4defa4..82afb0cdcca3 100644
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -141,7 +141,12 @@ static struct ib_uobject *alloc_uobj(struct ib_ucontext *context,
*/
uobj->context = context;
uobj->type = type;
- atomic_set(&uobj->usecnt, 0);
+ /*
+ * Allocated objects start out as write locked to deny any other
+ * syscalls from accessing them until they are commited. See
+ * rdma_alloc_commit_uobject
+ */
+ atomic_set(&uobj->usecnt, -1);
kref_init(&uobj->ref);
return uobj;
@@ -527,6 +532,10 @@ int rdma_alloc_commit_uobject(struct ib_uobject *uobj)
return ret;
}
+ /* matches atomic_set(-1) in alloc_uobj */
+ lockdep_check(uobj, true);
+ atomic_set(&uobj->usecnt, 0);
+
uobj->type->type_class->alloc_commit(uobj);
up_read(&uobj->context->cleanup_rwsem);
--
2.16.1
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