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libfc: Update rport reference counting
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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 <hare@suse.com>
Acked-by: Vasu Dev <vasu.dev@intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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Hannes Reinecke authored and Martin K. Petersen committed Jul 13, 2016
1 parent 7e1ee44 commit baa6719
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Showing 3 changed files with 38 additions and 37 deletions.
7 changes: 1 addition & 6 deletions drivers/scsi/fcoe/fcoe_ctlr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
}

Expand Down Expand Up @@ -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) {
Expand Down
19 changes: 12 additions & 7 deletions drivers/scsi/libfc/fc_lport.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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:
Expand Down
49 changes: 25 additions & 24 deletions drivers/scsi/libfc/fc_rport.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
}

/**
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -702,7 +706,7 @@ static void fc_rport_flogi_resp(struct fc_seq *sp, struct fc_frame *fp,
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");
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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:
Expand All @@ -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));
Expand All @@ -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);
}
Expand Down Expand Up @@ -923,7 +926,7 @@ static void fc_rport_plogi_resp(struct fc_seq *sp, struct fc_frame *fp,
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
Expand Down Expand Up @@ -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:
Expand All @@ -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;
}

Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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);
Expand All @@ -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);
}

Expand Down

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