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IB/uverbs: Hold the uobj write lock after allocate

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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);