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[SCSI] libfc: convert rport lookup to be RCU safe

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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@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
This commit is contained in:
Joe Eykholt 2010-07-20 15:19:37 -07:00 committed by James Bottomley
parent 519e5135e2
commit 42e9041467
3 changed files with 23 additions and 7 deletions
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6
drivers/scsi/libfc/fc_disc.c
View File

@ -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)

22
drivers/scsi/libfc/fc_rport.c
View File

@ -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;
@ -146,10 +148,22 @@ 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);
}

2
include/scsi/libfc.h
View File

@ -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;
};
/**