On Tue, Oct 27, 2020 at 09:20:36AM -0300, Jason Gunthorpe wrote: > There are two flows for handling RDMA_CM_EVENT_ROUTE_RESOLVED, either the > handler triggers a completion and another thread does rdma_connect() or > the handler directly calls rdma_connect(). > > In all cases rdma_connect() needs to hold the handler_mutex, but when > handler's are invoked this is already held by the core code. This causes > ULPs using the 2nd method to deadlock. > > Provide a rdma_connect_locked() and have all ULPs call it from their > handlers. > > Link: https://lore.kernel.org/r/0-v1-75e124dbad74+b05-rdma_connect_locking_jgg@xxxxxxxxxx > Reported-and-tested-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx> > Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state") > Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx> > Acked-by: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > --- > drivers/infiniband/core/cma.c | 40 +++++++++++++++++++++--- > drivers/infiniband/ulp/iser/iser_verbs.c | 2 +- > drivers/infiniband/ulp/rtrs/rtrs-clt.c | 4 +-- > drivers/nvme/host/rdma.c | 4 +-- > include/rdma/rdma_cm.h | 14 ++------- > net/rds/ib_cm.c | 5 +-- > 6 files changed, 46 insertions(+), 23 deletions(-) > > v2: > - Remove extra code from nvme (Chao) > - Fix long lines (CH) > > I've applied this version to rdma-rc - expecting to get these ULPs unbroken for rc2 > release > > Thanks, > Jason > > diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c > index 7c2ab1f2fbea37..193c8902b9db26 100644 > --- a/drivers/infiniband/core/cma.c > +++ b/drivers/infiniband/core/cma.c > @@ -405,10 +405,10 @@ static int cma_comp_exch(struct rdma_id_private *id_priv, > /* > * The FSM uses a funny double locking where state is protected by both > * the handler_mutex and the spinlock. State is not allowed to change > - * away from a handler_mutex protected value without also holding > + * to/from a handler_mutex protected value without also holding > * handler_mutex. > */ > - if (comp == RDMA_CM_CONNECT) > + if (comp == RDMA_CM_CONNECT || exch == RDMA_CM_CONNECT) > lockdep_assert_held(&id_priv->handler_mutex); > > spin_lock_irqsave(&id_priv->lock, flags); > @@ -4038,13 +4038,21 @@ static int cma_connect_iw(struct rdma_id_private *id_priv, > return ret; > } > > -int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param) > +/** > + * rdma_connect_locked - Initiate an active connection request. > + * @id: Connection identifier to connect. > + * @conn_param: Connection information used for connected QPs. > + * > + * Same as rdma_connect() but can only be called from the > + * RDMA_CM_EVENT_ROUTE_RESOLVED handler callback. > + */ > +int rdma_connect_locked(struct rdma_cm_id *id, > + struct rdma_conn_param *conn_param) > { > struct rdma_id_private *id_priv = > container_of(id, struct rdma_id_private, id); > int ret; > > - mutex_lock(&id_priv->handler_mutex); > if (!cma_comp_exch(id_priv, RDMA_CM_ROUTE_RESOLVED, RDMA_CM_CONNECT)) { > ret = -EINVAL; > goto err_unlock; Not a big deal, but his label is not correct anymore. Thanks
