On Wed, Mar 15, 2023 at 3:05 PM Bob Pearson <rpearsonhpe@xxxxxxxxx> wrote: > > On 3/15/23 13:41, Joel Fernandes wrote: > > On Wed, Mar 15, 2023 at 2:38 PM Bob Pearson <rpearsonhpe@xxxxxxxxx> wrote: > >> > >> On 3/15/23 13:19, Joel Fernandes (Google) wrote: > >>> The k[v]free_rcu() macro's single-argument form is deprecated. > >>> Therefore switch to the new k[v]free_rcu_mightsleep() variant. The goal > >>> is to avoid accidental use of the single-argument forms, which can > >>> introduce functionality bugs in atomic contexts and latency bugs in > >>> non-atomic contexts. > >>> > >>> There is no functionality change with this patch. > >>> > >>> Link: https://lore.kernel.org/rcu/20230201150815.409582-1-urezki@xxxxxxxxx > >>> Acked-by: Zhu Yanjun <zyjzyj2000@xxxxxxxxx> > >>> Reviewed-by: Bob Pearson <rpearsonhpe@xxxxxxxxx> > >>> Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > >>> Fixes: 72a03627443d ("RDMA/rxe: Remove rxe_alloc()") > >>> Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > >>> --- > >>> drivers/infiniband/sw/rxe/rxe_mr.c | 2 +- > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c > >>> index b10aa1580a64..ae3a100e18fb 100644 > >>> --- a/drivers/infiniband/sw/rxe/rxe_mr.c > >>> +++ b/drivers/infiniband/sw/rxe/rxe_mr.c > >>> @@ -731,7 +731,7 @@ int rxe_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata) > >>> return -EINVAL; > >>> > >>> rxe_cleanup(mr); > >>> - kfree_rcu(mr); > >>> + kfree_rcu_mightsleep(mr); > >>> return 0; > >>> } > >>> > >> Please replace kfree_rcu_mightsleep() by kfree(). There is no need to delay the kfree(mr). > > > > I thought you said either was Ok, but yeah that's fine with me. I was > > trying to play it safe ;-). An extra GP may not hurt, but not having > > one when it is needed might. I will update it to just be kfree. > > Thanks. The reason to not add the pause is that it really isn't required and will just make > people think that it is. With the current state of the driver the mr cleanup code will disable > looking up the mr from its rkey or lkey and then wait until all the references to the mr are dropped > before calling kfree. This will always work (unless a new bug is introduced) so no reason to > add the rcu delay. > Sounds good! I updated it in my queue, and I will repost it in the future pending test results and other comments. thanks, - Joel
