From: Joe Eykholt <jeykholt@xxxxxxxxx>
To allow LLD to do lookups on rports without grabbing a mutex,
make them RCU-safe. The caller of lport->tt.rport_lookup will
have the choice of holding disc_mutex or the rcu_read_lock().
Signed-off-by: Joe Eykholt <jeykholt@xxxxxxxxx>
Signed-off-by: Robert Love <robert.w.love@xxxxxxxxx>
---
drivers/scsi/libfc/fc_disc.c | 6 +++---
drivers/scsi/libfc/fc_rport.c | 22 ++++++++++++++++++----
include/scsi/libfc.h | 2 ++
3 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/libfc/fc_disc.c b/drivers/scsi/libfc/fc_disc.c
index c7985da..d0fa9a0 100644
--- a/drivers/scsi/libfc/fc_disc.c
+++ b/drivers/scsi/libfc/fc_disc.c
@@ -63,12 +63,12 @@ static void fc_disc_restart(struct fc_disc *);
void fc_disc_stop_rports(struct fc_disc *disc)
{
struct fc_lport *lport;
- struct fc_rport_priv *rdata, *next;
+ struct fc_rport_priv *rdata;
lport = disc->lport;
mutex_lock(&disc->disc_mutex);
- list_for_each_entry_safe(rdata, next, &disc->rports, peers)
+ list_for_each_entry_rcu(rdata, &disc->rports, peers)
lport->tt.rport_logoff(rdata);
mutex_unlock(&disc->disc_mutex);
}
@@ -292,7 +292,7 @@ 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.
*/
- list_for_each_entry(rdata, &disc->rports, peers) {
+ list_for_each_entry_rcu(rdata, &disc->rports, peers) {
if (!rdata->disc_id)
continue;
if (rdata->disc_id == disc->disc_id)
diff --git a/drivers/scsi/libfc/fc_rport.c b/drivers/scsi/libfc/fc_rport.c
index 363cde3..6b56973 100644
--- a/drivers/scsi/libfc/fc_rport.c
+++ b/drivers/scsi/libfc/fc_rport.c
@@ -95,13 +95,15 @@ static const char *fc_rport_state_names[] = {
* fc_rport_lookup() - Lookup a remote port by port_id
* @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().
*/
static struct fc_rport_priv *fc_rport_lookup(const struct fc_lport *lport,
u32 port_id)
{
struct fc_rport_priv *rdata;
- list_for_each_entry(rdata, &lport->disc.rports, peers)
+ list_for_each_entry_rcu(rdata, &lport->disc.rports, peers)
if (rdata->ids.port_id == port_id)
return rdata;
return NULL;
@@ -146,11 +148,23 @@ static struct fc_rport_priv *fc_rport_create(struct fc_lport *lport,
INIT_DELAYED_WORK(&rdata->retry_work, fc_rport_timeout);
INIT_WORK(&rdata->event_work, fc_rport_work);
if (port_id != FC_FID_DIR_SERV)
- list_add(&rdata->peers, &lport->disc.rports);
+ list_add_rcu(&rdata->peers, &lport->disc.rports);
return rdata;
}
/**
+ * fc_rport_free_rcu() - Free a remote port
+ * @rcu: The rcu_head structure inside the remote port
+ */
+static void fc_rport_free_rcu(struct rcu_head *rcu)
+{
+ struct fc_rport_priv *rdata;
+
+ rdata = container_of(rcu, struct fc_rport_priv, rcu);
+ kfree(rdata);
+}
+
+/**
* fc_rport_destroy() - Free a remote port after last reference is released
* @kref: The remote port's kref
*/
@@ -159,7 +173,7 @@ static void fc_rport_destroy(struct kref *kref)
struct fc_rport_priv *rdata;
rdata = container_of(kref, struct fc_rport_priv, kref);
- kfree(rdata);
+ call_rcu(&rdata->rcu, fc_rport_free_rcu);
}
/**
@@ -334,7 +348,7 @@ static void fc_rport_work(struct work_struct *work)
mutex_unlock(&rdata->rp_mutex);
} else {
FC_RPORT_DBG(rdata, "work delete\n");
- list_del(&rdata->peers);
+ list_del_rcu(&rdata->peers);
mutex_unlock(&rdata->rp_mutex);
kref_put(&rdata->kref, lport->tt.rport_destroy);
}
diff --git a/include/scsi/libfc.h b/include/scsi/libfc.h
index 6d78df7..b0310b9 100644
--- a/include/scsi/libfc.h
+++ b/include/scsi/libfc.h
@@ -195,6 +195,7 @@ struct fc_rport_libfc_priv {
* @rp_mutex: The mutex that protects the remote port
* @retry_work: Handle for retries
* @event_callback: Callback when READY, FAILED or LOGO states complete
+ * @rcu: Structure used for freeing in an RCU-safe manner
*/
struct fc_rport_priv {
struct fc_lport *local_port;
@@ -217,6 +218,7 @@ struct fc_rport_priv {
struct list_head peers;
struct work_struct event_work;
u32 supported_classes;
+ struct rcu_head rcu;
};
/**
--
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