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IB/uverbs: Hold the uobj write lock after allocate 

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: 3832125624 ("IB/core: Add support for idr types")
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Jason Gunthorpe 2018-02-13 12:18:36 +02:00
parent 4d39a959bc
commit d9dc7a3500
1 changed files with 10 additions and 1 deletions
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11
drivers/infiniband/core/rdma_core.c
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@ -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 committed. 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);