RDMA/rxe: Fix an error handling path in rxe_get_mcg()

The commit in the Fixes tag has shuffled some code.
Now 'mcg_num' is incremented before the kzalloc(). So if the memory
allocation fails, this increment must be undone.

Fixes: a926a903b7dc ("RDMA/rxe: Do not call dev_mc_add/del() under a spinlock")
Link: https://lore.kernel.org/r/fe137cd8b1f17593243aa73d59c18ea71ab9ee36.1653225896.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/sw/rxe/rxe_mcast.c b/drivers/infiniband/sw/rxe/rxe_mcast.c
index 873a9b1..86cc2e1 100644 (file)
--- a/drivers/infiniband/sw/rxe/rxe_mcast.c
+++ b/drivers/infiniband/sw/rxe/rxe_mcast.c
@@ -206,8 +206,10 @@ static struct rxe_mcg *rxe_get_mcg(struct rxe_dev *rxe, union ib_gid *mgid)
 
        /* speculative alloc of new mcg */
        mcg = kzalloc(sizeof(*mcg), GFP_KERNEL);
-       if (!mcg)
-               return ERR_PTR(-ENOMEM);
+       if (!mcg) {
+               err = -ENOMEM;
+               goto err_dec;
+       }
 
        spin_lock_bh(&rxe->mcg_lock);
        /* re-check to see if someone else just added it */