scsi: libfc: Fixup disc_mutex handling
The list of attached 'rdata' remote port structures is RCU
protected, so there is no need to take the 'disc_mutex' when
traversing it.
Rather we should be using rcu_read_lock() and kref_get_unless_zero()
to validate the entries.
We need, however, take the disc_mutex when deleting an entry;
otherwise we risk clashes with list_add.
Signed-off-by: Hannes Reinecke <hare@suse.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/libfc/fc_disc.c b/drivers/scsi/libfc/fc_disc.c
index 880a906..ad3965f 100644
--- a/drivers/scsi/libfc/fc_disc.c
+++ b/drivers/scsi/libfc/fc_disc.c
@@ -68,10 +68,14 @@ static void fc_disc_stop_rports(struct fc_disc *disc)
lport = fc_disc_lport(disc);
- mutex_lock(&disc->disc_mutex);
- list_for_each_entry_rcu(rdata, &disc->rports, peers)
- lport->tt.rport_logoff(rdata);
- mutex_unlock(&disc->disc_mutex);
+ rcu_read_lock();
+ list_for_each_entry_rcu(rdata, &disc->rports, peers) {
+ if (kref_get_unless_zero(&rdata->kref)) {
+ lport->tt.rport_logoff(rdata);
+ kref_put(&rdata->kref, lport->tt.rport_destroy);
+ }
+ }
+ rcu_read_unlock();
}
/**
@@ -289,15 +293,19 @@ static void fc_disc_done(struct fc_disc *disc, enum fc_disc_event event)
* Skip ports which were never discovered. These are the dNS port
* and ports which were created by PLOGI.
*/
+ rcu_read_lock();
list_for_each_entry_rcu(rdata, &disc->rports, peers) {
- if (!rdata->disc_id)
+ if (!kref_get_unless_zero(&rdata->kref))
continue;
- if (rdata->disc_id == disc->disc_id)
- lport->tt.rport_login(rdata);
- else
- lport->tt.rport_logoff(rdata);
+ if (rdata->disc_id) {
+ if (rdata->disc_id == disc->disc_id)
+ lport->tt.rport_login(rdata);
+ else
+ lport->tt.rport_logoff(rdata);
+ }
+ kref_put(&rdata->kref, lport->tt.rport_destroy);
}
-
+ rcu_read_unlock();
mutex_unlock(&disc->disc_mutex);
disc->disc_callback(lport, event);
mutex_lock(&disc->disc_mutex);
@@ -592,7 +600,6 @@ static void fc_disc_gpn_id_resp(struct fc_seq *sp, struct fc_frame *fp,
lport = rdata->local_port;
disc = &lport->disc;
- mutex_lock(&disc->disc_mutex);
if (PTR_ERR(fp) == -FC_EX_CLOSED)
goto out;
if (IS_ERR(fp))
@@ -607,16 +614,19 @@ static void fc_disc_gpn_id_resp(struct fc_seq *sp, struct fc_frame *fp,
goto redisc;
pn = (struct fc_ns_gid_pn *)(cp + 1);
port_name = get_unaligned_be64(&pn->fn_wwpn);
+ mutex_lock(&rdata->rp_mutex);
if (rdata->ids.port_name == -1)
rdata->ids.port_name = port_name;
else if (rdata->ids.port_name != port_name) {
FC_DISC_DBG(disc, "GPN_ID accepted. WWPN changed. "
"Port-id %6.6x wwpn %16.16llx\n",
rdata->ids.port_id, port_name);
+ mutex_unlock(&rdata->rp_mutex);
lport->tt.rport_logoff(rdata);
-
+ mutex_lock(&lport->disc.disc_mutex);
new_rdata = lport->tt.rport_create(lport,
rdata->ids.port_id);
+ mutex_unlock(&lport->disc.disc_mutex);
if (new_rdata) {
new_rdata->disc_id = disc->disc_id;
lport->tt.rport_login(new_rdata);
@@ -624,6 +634,7 @@ static void fc_disc_gpn_id_resp(struct fc_seq *sp, struct fc_frame *fp,
goto out;
}
rdata->disc_id = disc->disc_id;
+ mutex_unlock(&rdata->rp_mutex);
lport->tt.rport_login(rdata);
} else if (ntohs(cp->ct_cmd) == FC_FS_RJT) {
FC_DISC_DBG(disc, "GPN_ID rejected reason %x exp %x\n",
@@ -633,10 +644,11 @@ static void fc_disc_gpn_id_resp(struct fc_seq *sp, struct fc_frame *fp,
FC_DISC_DBG(disc, "GPN_ID unexpected response code %x\n",
ntohs(cp->ct_cmd));
redisc:
+ mutex_lock(&disc->disc_mutex);
fc_disc_restart(disc);
+ mutex_unlock(&disc->disc_mutex);
}
out:
- mutex_unlock(&disc->disc_mutex);
kref_put(&rdata->kref, lport->tt.rport_destroy);
}