Re: [PATCH for-next v3 2/8] RDMA/rxe: Warn if refcnt zero in rxe_put

Jason Gunthorpe
2023-03-24T14:18:14Z

On Sat, Mar 04, 2023 at 11:45:28AM -0600, Bob Pearson wrote:
> This patch adds a WARN_ON if the reference count of the object
> passed to __rxe_put() is <= 0. This can only happen if there is a
> bug in the rxe driver but has bad consequences if there is.
>
> Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
> ---
> drivers/infiniband/sw/rxe/rxe_pool.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
> index 3f6bd672cc2d..1b160e36b751 100644
> --- a/drivers/infiniband/sw/rxe/rxe_pool.c
> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c
> @@ -244,6 +244,8 @@ int __rxe_get(struct rxe_pool_elem *elem)
>
> int __rxe_put(struct rxe_pool_elem *elem)
> {
> + if (WARN_ON(kref_read(&elem->ref_cnt) <= 0))
> + return 0;
> return kref_put(&elem->ref_cnt, rxe_elem_release);

refcount debugging in kref_put already does this kind of stuff, don't
need to open code it.

Jason