On Tue, 2016-05-24 at 08:11 +0200, Hannes Reinecke wrote:
> Originally libfc would just be initializing the refcount to '1',
> and using the disc_mutex to synchronize if and when the final put
> should be happening.
> This has a race condition as the mutex might be delayed, causing
> other threads to access an invalid structure.
> This patch updates the rport reference counting to increase the
> reference every time 'rport_lookup' is called, and decreases
> the reference correspondingly.
> This removes the need to hold 'disc_mutex' when removing the
> structure, and avoids the above race condition.
>
> Signed-off-by: Hannes Reinecke <h...@suse.com>
> ---
> drivers/scsi/fcoe/fcoe_ctlr.c | 7 +------
> drivers/scsi/libfc/fc_lport.c | 19 ++++++++++-------
> drivers/scsi/libfc/fc_rport.c | 49 ++++++++++++++++++++++-----------
> ----------
> 3 files changed, 38 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c
> b/drivers/scsi/fcoe/fcoe_ctlr.c
> index 3e83d48..ada4bde 100644
> --- a/drivers/scsi/fcoe/fcoe_ctlr.c
> +++ b/drivers/scsi/fcoe/fcoe_ctlr.c
> @@ -2496,14 +2496,13 @@ static int fcoe_ctlr_vn_lookup(struct
> fcoe_ctlr *fip, u32 port_id, u8 *mac)
> struct fcoe_rport *frport;
> int ret = -1;
>
> - rcu_read_lock();
> rdata = lport->tt.rport_lookup(lport, port_id);
> if (rdata) {
> frport = fcoe_ctlr_rport(rdata);
> memcpy(mac, frport->enode_mac, ETH_ALEN);
> ret = 0;
> + kref_put(&rdata->kref, lport->tt.rport_destroy);
> }
> - rcu_read_unlock();
> return ret;
> }
>
> @@ -2585,11 +2584,7 @@ static void fcoe_ctlr_vn_beacon(struct
> fcoe_ctlr *fip,
> fcoe_ctlr_vn_send(fip, FIP_SC_VN_PROBE_REQ,
> fcoe_all_vn2vn, 0);
> return;
> }
> - mutex_lock(&lport->disc.disc_mutex);
> rdata = lport->tt.rport_lookup(lport, new->ids.port_id);
> - if (rdata)
> - kref_get(&rdata->kref);
> - mutex_unlock(&lport->disc.disc_mutex);
> if (rdata) {
> if (rdata->ids.node_name == new->ids.node_name &&
> rdata->ids.port_name == new->ids.port_name) {
> diff --git a/drivers/scsi/libfc/fc_lport.c
> b/drivers/scsi/libfc/fc_lport.c
> index e01a298..b9b44da 100644
> --- a/drivers/scsi/libfc/fc_lport.c
> +++ b/drivers/scsi/libfc/fc_lport.c
> @@ -2090,7 +2090,7 @@ int fc_lport_bsg_request(struct fc_bsg_job
> *job)
> struct fc_rport *rport;
> struct fc_rport_priv *rdata;
> int rc = -EINVAL;
> - u32 did;
> + u32 did, tov;
>
> job->reply->reply_payload_rcv_len = 0;
> if (rsp)
> @@ -2121,15 +2121,20 @@ int fc_lport_bsg_request(struct fc_bsg_job
> *job)
>
> case FC_BSG_HST_CT:
> did = ntoh24(job->request->rqst_data.h_ct.port_id);
> - if (did == FC_FID_DIR_SERV)
> + if (did == FC_FID_DIR_SERV) {
> rdata = lport->dns_rdata;
> - else
> + if (!rdata)
> + break;
> + tov = rdata->e_d_tov;
> + } else {
> rdata = lport->tt.rport_lookup(lport, did);
> + if (!rdata)
> + break;
> + tov = rdata->e_d_tov;
> + kref_put(&rdata->kref, lport-
> >tt.rport_destroy);
> + }
>
> - if (!rdata)
> - break;
> -
> - rc = fc_lport_ct_request(job, lport, did, rdata-
> >e_d_tov);
> + rc = fc_lport_ct_request(job, lport, did, tov);
> break;
>
> case FC_BSG_HST_ELS_NOLOGIN:
> diff --git a/drivers/scsi/libfc/fc_rport.c
> b/drivers/scsi/libfc/fc_rport.c
> index 589ff9a..93f5961 100644
> --- a/drivers/scsi/libfc/fc_rport.c
> +++ b/drivers/scsi/libfc/fc_rport.c
> @@ -95,17 +95,23 @@ static const char *fc_rport_state_names[] = {
> * @lport: The local port to lookup the remote port on
> * @port_id: The remote port ID to look up
> *
> - * The caller must hold either disc_mutex or rcu_read_lock().
> + * The reference count of the fc_rport_priv structure is
> + * increased by one.
> */
> static struct fc_rport_priv *fc_rport_lookup(const struct fc_lport
> *lport,
> u32 port_id)
> {
> - struct fc_rport_priv *rdata;
> + struct fc_rport_priv *rdata = NULL, *tmp_rdata;
>
> - list_for_each_entry_rcu(rdata, &lport->disc.rports, peers)
> - if (rdata->ids.port_id == port_id)
> - return rdata;
> - return NULL;
> + rcu_read_lock();
> + list_for_each_entry_rcu(tmp_rdata, &lport->disc.rports,
> peers)
> + if (tmp_rdata->ids.port_id == port_id &&
> + kref_get_unless_zero(&tmp_rdata->kref)) {
> + rdata = tmp_rdata;
> + break;
> + }
> + rcu_read_unlock();
> + return rdata;
> }
>
> /**
> @@ -340,7 +346,6 @@ static void fc_rport_work(struct work_struct
> *work)
> fc_remote_port_delete(rport);
> }
>
> - mutex_lock(&lport->disc.disc_mutex);
> mutex_lock(&rdata->rp_mutex);
> if (rdata->rp_state == RPORT_ST_DELETE) {
> if (port_id == FC_FID_DIR_SERV) {
> @@ -370,7 +375,6 @@ static void fc_rport_work(struct work_struct
> *work)
> fc_rport_enter_ready(rdata);
> mutex_unlock(&rdata->rp_mutex);
> }
> - mutex_unlock(&lport->disc.disc_mutex);
> break;
>
> default:
> @@ -702,7 +706,7 @@ out:
> err:
> mutex_unlock(&rdata->rp_mutex);
> put:
> - kref_put(&rdata->kref, rdata->local_port->tt.rport_destroy);
> + kref_put(&rdata->kref, lport->tt.rport_destroy);
> return;
> bad:
> FC_RPORT_DBG(rdata, "Bad FLOGI response\n");
> @@ -762,8 +766,6 @@ static void fc_rport_recv_flogi_req(struct
> fc_lport *lport,
> FC_RPORT_ID_DBG(lport, sid, "Received FLOGI request\n");
>
> disc = &lport->disc;
> - mutex_lock(&disc->disc_mutex);
> -
> if (!lport->point_to_multipoint) {
> rjt_data.reason = ELS_RJT_UNSUP;
> rjt_data.explan = ELS_EXPL_NONE;
> @@ -808,7 +810,7 @@ static void fc_rport_recv_flogi_req(struct
> fc_lport *lport,
> mutex_unlock(&rdata->rp_mutex);
> rjt_data.reason = ELS_RJT_FIP;
> rjt_data.explan = ELS_EXPL_NOT_NEIGHBOR;
> - goto reject;
> + goto reject_put;
> case RPORT_ST_FLOGI:
> case RPORT_ST_PLOGI_WAIT:
> case RPORT_ST_PLOGI:
> @@ -825,13 +827,13 @@ static void fc_rport_recv_flogi_req(struct
> fc_lport *lport,
> mutex_unlock(&rdata->rp_mutex);
> rjt_data.reason = ELS_RJT_BUSY;
> rjt_data.explan = ELS_EXPL_NONE;
> - goto reject;
> + goto reject_put;
> }
> if (fc_rport_login_complete(rdata, fp)) {
> mutex_unlock(&rdata->rp_mutex);
> rjt_data.reason = ELS_RJT_LOGIC;
> rjt_data.explan = ELS_EXPL_NONE;
> - goto reject;
> + goto reject_put;
> }
>
> fp = fc_frame_alloc(lport, sizeof(*flp));
> @@ -851,12 +853,13 @@ static void fc_rport_recv_flogi_req(struct
> fc_lport *lport,
> fc_rport_state_enter(rdata, RPORT_ST_PLOGI_WAIT);
> out:
> mutex_unlock(&rdata->rp_mutex);
> - mutex_unlock(&disc->disc_mutex);
> + kref_put(&rdata->kref, lport->tt.rport_destroy);
> fc_frame_free(rx_fp);
> return;
>
> +reject_put:
> + kref_put(&rdata->kref, lport->tt.rport_destroy);
> reject:
> - mutex_unlock(&disc->disc_mutex);
> lport->tt.seq_els_rsp_send(rx_fp, ELS_LS_RJT, &rjt_data);
> fc_frame_free(rx_fp);
> }
> @@ -923,7 +926,7 @@ out:
> fc_frame_free(fp);
> err:
> mutex_unlock(&rdata->rp_mutex);
> - kref_put(&rdata->kref, rdata->local_port->tt.rport_destroy);
> + kref_put(&rdata->kref, lport->tt.rport_destroy);
> }
>
> static bool
> @@ -1477,14 +1480,11 @@ static void fc_rport_recv_els_req(struct
> fc_lport *lport, struct fc_frame *fp)
> struct fc_rport_priv *rdata;
> struct fc_seq_els_data els_data;
>
> - mutex_lock(&lport->disc.disc_mutex);
> rdata = lport->tt.rport_lookup(lport, fc_frame_sid(fp));
> - if (!rdata) {
> - mutex_unlock(&lport->disc.disc_mutex);
> + if (!rdata)
> goto reject;
> - }
> +
> mutex_lock(&rdata->rp_mutex);
> - mutex_unlock(&lport->disc.disc_mutex);
>
> switch (rdata->rp_state) {
> case RPORT_ST_PRLI:
> @@ -1494,6 +1494,7 @@ static void fc_rport_recv_els_req(struct
> fc_lport *lport, struct fc_frame *fp)
> break;
> default:
> mutex_unlock(&rdata->rp_mutex);
> + kref_put(&rdata->kref, lport->tt.rport_destroy);
> goto reject;
> }
>
> @@ -1524,6 +1525,7 @@ static void fc_rport_recv_els_req(struct
> fc_lport *lport, struct fc_frame *fp)
> }
>
> mutex_unlock(&rdata->rp_mutex);
> + kref_put(&rdata->kref, rdata->local_port->tt.rport_destroy);
> return;
>
> reject:
> @@ -1907,7 +1909,6 @@ static void fc_rport_recv_logo_req(struct
> fc_lport *lport, struct fc_frame *fp)
>
> sid = fc_frame_sid(fp);
>
> - mutex_lock(&lport->disc.disc_mutex);
> rdata = lport->tt.rport_lookup(lport, sid);
> if (rdata) {
> mutex_lock(&rdata->rp_mutex);
> @@ -1916,10 +1917,10 @@ static void fc_rport_recv_logo_req(struct
> fc_lport *lport, struct fc_frame *fp)
>
> fc_rport_enter_delete(rdata, RPORT_EV_LOGO);
> mutex_unlock(&rdata->rp_mutex);
> + kref_put(&rdata->kref, rdata->local_port-
> >tt.rport_destroy);
> } else
> FC_RPORT_ID_DBG(lport, sid,
> "Received LOGO from non-logged-in
> port\n");
> - mutex_unlock(&lport->disc.disc_mutex);
> fc_frame_free(fp);
> }
Looks good.
Acked-by: Vasu Dev <vasu....@intel.com>
>
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