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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=66vHYoqa6whG3krPCX3D1qlK8K0wfzKnD+NhnstScx4=; b=KM4V7tqpcZshEeF3kHydV1O8EMoWy99wLyfcfJLQT5ffp1vS0F24HfIqVO25EWLKQv uO+wWidZukxaRlFWNKhy07W6klWVa8nF/ZC6jM/BZZidEhrQs04gtHXsbywMba+OnjX/ SqTh71e/cvngc8cc9P0gnMHywPDtk+/xtp1AbMGF8aIH90XCByn7r52WCTpXDn/DTgTo lqsSy8qeO0NRziTpFEeIaGaGfPamdJQPEDR6RkyipyQo1zCjx/62gf5aKa4r0IachY3C 2H5iQKbXO38cWAwXGJ7b5O8oTp+zaIoE1lg7hvn+kX7vBgq+URi6RUp6T9qhpyq/uplM QO2g== X-Gm-Message-State: AOAM531Igg/VZybkuB2F30kp9h1vJGTuBx55CF9rxPab6EsISn6UKGUN lNoeMI7sGHRXV6gE6vsk2LBtz0lGHKH+z23zkliUCw== X-Google-Smtp-Source: ABdhPJwovVYMOgNA6lm9ValuONtBFeUvdbi0QJpCmUz1VYt5VbCBXmATuHDW5H8plOfkX7+mj2n5DJcOXdjPz0g8ESI= X-Received: by 2002:a50:e40c:: with SMTP id d12mr835831edm.35.1603784036319; Tue, 27 Oct 2020 00:33:56 -0700 (PDT) MIME-Version: 1.0 References: <0-v1-75e124dbad74+b05-rdma_connect_locking_jgg@nvidia.com> In-Reply-To: <0-v1-75e124dbad74+b05-rdma_connect_locking_jgg@nvidia.com> From: Jinpu Wang Date: Tue, 27 Oct 2020 08:33:45 +0100 Message-ID: Subject: Re: [PATCH] RDMA: Add rdma_connect_locked() To: Jason Gunthorpe X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201027_033359_214113_D693E405 X-CRM114-Status: GOOD ( 27.96 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Max Gurtovoy , rds-devel@oss.oracle.com, Sagi Grimberg , linux-rdma@vger.kernel.org, netdev , Santosh Shilimkar , Guoqing Jiang , linux-nvme@lists.infradead.org, Doug Ledford , Danil Kipnis , Keith Busch , Leon Romanovsky , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Oct 26, 2020 at 3:25 PM 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. > > Reported-by: Guoqing Jiang > Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state" > Signed-off-by: Jason Gunthorpe > --- > drivers/infiniband/core/cma.c | 39 +++++++++++++++++++++--- > drivers/infiniband/ulp/iser/iser_verbs.c | 2 +- > drivers/infiniband/ulp/rtrs/rtrs-clt.c | 4 +-- > drivers/nvme/host/rdma.c | 10 +++--- > include/rdma/rdma_cm.h | 13 +------- > net/rds/ib_cm.c | 5 +-- > 6 files changed, 47 insertions(+), 26 deletions(-) > > Seems people are not testing these four ULPs against rdma-next.. Here is a > quick fix for the issue: > > https://lore.kernel.org/r/3b1f7767-98e2-93e0-b718-16d1c5346140@cloud.ionos.com > > Jason > > diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c > index 7c2ab1f2fbea37..2eaaa1292fb847 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 +4038,20 @@ 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; > @@ -4071,6 +4078,30 @@ int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param) > err_state: > cma_comp_exch(id_priv, RDMA_CM_CONNECT, RDMA_CM_ROUTE_RESOLVED); > err_unlock: > + return ret; > +} > +EXPORT_SYMBOL(rdma_connect_locked); > + > +/** > + * rdma_connect - Initiate an active connection request. > + * @id: Connection identifier to connect. > + * @conn_param: Connection information used for connected QPs. > + * > + * Users must have resolved a route for the rdma_cm_id to connect with by having > + * called rdma_resolve_route before calling this routine. > + * > + * This call will either connect to a remote QP or obtain remote QP information > + * for unconnected rdma_cm_id's. The actual operation is based on the > + * rdma_cm_id's port space. > + */ > +int rdma_connect(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); > + ret = rdma_connect_locked(id, conn_param); > mutex_unlock(&id_priv->handler_mutex); > return ret; > } > diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c > index 2f3ebc0a75d924..2bd18b00689341 100644 > --- a/drivers/infiniband/ulp/iser/iser_verbs.c > +++ b/drivers/infiniband/ulp/iser/iser_verbs.c > @@ -620,7 +620,7 @@ static void iser_route_handler(struct rdma_cm_id *cma_id) > conn_param.private_data = (void *)&req_hdr; > conn_param.private_data_len = sizeof(struct iser_cm_hdr); > > - ret = rdma_connect(cma_id, &conn_param); > + ret = rdma_connect_locked(cma_id, &conn_param); > if (ret) { > iser_err("failure connecting: %d\n", ret); > goto failure; > diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c > index 776e89231c52f7..f298adc02acba2 100644 > --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c > +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c > @@ -1674,9 +1674,9 @@ static int rtrs_rdma_route_resolved(struct rtrs_clt_con *con) > uuid_copy(&msg.sess_uuid, &sess->s.uuid); > uuid_copy(&msg.paths_uuid, &clt->paths_uuid); > > - err = rdma_connect(con->c.cm_id, ¶m); > + err = rdma_connect_locked(con->c.cm_id, ¶m); > if (err) > - rtrs_err(clt, "rdma_connect(): %d\n", err); > + rtrs_err(clt, "rdma_connect_locked(): %d\n", err); > > return err; > } For rtrs, looks good to me! Thanks for the quick fix. Acked-by: Jack Wang _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme