[PATCH v2] scsi: libsas: cleanup sas_form_port()

* [PATCH v2] scsi: libsas: cleanup sas_form_port()
@ 2022-02-28  9:48 Damien Le Moal
  2022-02-28 10:08 ` John Garry
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Damien Le Moal @ 2022-02-28  9:48 UTC (permalink / raw)
  To: linux-scsi, Martin K . Petersen, John Garry, Dan Carpenter, Jason Yan

Sparse throws a warning about context imbalance ("different lock
contexts for basic block") in sas_form_port() as it gets confused with
the fact that a port is locked within one of the 2 search loop and
unlocked afterward outside of the search loops once the phy is added to
the port. Since this code is not easy to follow, improve it by factoring
out the code adding the phy to the port once the port is locked into the
helper function sas_form_port_add_phy(). This helper can then be called
directly within the port search loops, avoiding confusion and clearing
the sparse warning.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
Changes from v1:
* Renamed helper function to sas_form_port_add_phy()

 drivers/scsi/libsas/sas_port.c | 73 +++++++++++++++++++---------------
 1 file changed, 42 insertions(+), 31 deletions(-)

diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index 67b429dcf1ff..11599c0e3fc3 100644
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -67,6 +67,34 @@ static void sas_resume_port(struct asd_sas_phy *phy)
 	sas_discover_event(port, DISCE_RESUME);
 }
 
+static void sas_form_port_add_phy(struct asd_sas_port *port,
+				  struct asd_sas_phy *phy, bool wideport)
+{
+	list_add_tail(&phy->port_phy_el, &port->phy_list);
+	sas_phy_set_target(phy, port->port_dev);
+	phy->port = port;
+	port->num_phys++;
+	port->phy_mask |= (1U << phy->id);
+
+	if (wideport)
+		pr_debug("phy%d matched wide port%d\n", phy->id,
+			 port->id);
+	else
+		memcpy(port->sas_addr, phy->sas_addr, SAS_ADDR_SIZE);
+
+	if (*(u64 *)port->attached_sas_addr == 0) {
+		port->class = phy->class;
+		memcpy(port->attached_sas_addr, phy->attached_sas_addr,
+		       SAS_ADDR_SIZE);
+		port->iproto = phy->iproto;
+		port->tproto = phy->tproto;
+		port->oob_mode = phy->oob_mode;
+		port->linkrate = phy->linkrate;
+	} else {
+		port->linkrate = max(port->linkrate, phy->linkrate);
+	}
+}
+
 /**
  * sas_form_port - add this phy to a port
  * @phy: the phy of interest
@@ -79,7 +107,7 @@ static void sas_form_port(struct asd_sas_phy *phy)
 	int i;
 	struct sas_ha_struct *sas_ha = phy->ha;
 	struct asd_sas_port *port = phy->port;
-	struct domain_device *port_dev;
+	struct domain_device *port_dev = NULL;
 	struct sas_internal *si =
 		to_sas_internal(sas_ha->core.shost->transportt);
 	unsigned long flags;
@@ -110,8 +138,9 @@ static void sas_form_port(struct asd_sas_phy *phy)
 		if (*(u64 *) port->sas_addr &&
 		    phy_is_wideport_member(port, phy) && port->num_phys > 0) {
 			/* wide port */
-			pr_debug("phy%d matched wide port%d\n", phy->id,
-				 port->id);
+			port_dev = port->port_dev;
+			sas_form_port_add_phy(port, phy, true);
+			spin_unlock(&port->phy_list_lock);
 			break;
 		}
 		spin_unlock(&port->phy_list_lock);
@@ -122,40 +151,22 @@ static void sas_form_port(struct asd_sas_phy *phy)
 			port = sas_ha->sas_port[i];
 			spin_lock(&port->phy_list_lock);
 			if (*(u64 *)port->sas_addr == 0
-				&& port->num_phys == 0) {
-				memcpy(port->sas_addr, phy->sas_addr,
-					SAS_ADDR_SIZE);
+			    && port->num_phys == 0) {
+				port_dev = port->port_dev;
+				sas_form_port_add_phy(port, phy, false);
+				spin_unlock(&port->phy_list_lock);
 				break;
 			}
 			spin_unlock(&port->phy_list_lock);
 		}
-	}
 
-	if (i >= sas_ha->num_phys) {
-		pr_err("%s: couldn't find a free port, bug?\n", __func__);
-		spin_unlock_irqrestore(&sas_ha->phy_port_lock, flags);
-		return;
+		if (i >= sas_ha->num_phys) {
+			pr_err("%s: couldn't find a free port, bug?\n",
+			       __func__);
+			spin_unlock_irqrestore(&sas_ha->phy_port_lock, flags);
+			return;
+		}
 	}
-
-	/* add the phy to the port */
-	port_dev = port->port_dev;
-	list_add_tail(&phy->port_phy_el, &port->phy_list);
-	sas_phy_set_target(phy, port_dev);
-	phy->port = port;
-	port->num_phys++;
-	port->phy_mask |= (1U << phy->id);
-
-	if (*(u64 *)port->attached_sas_addr == 0) {
-		port->class = phy->class;
-		memcpy(port->attached_sas_addr, phy->attached_sas_addr,
-		       SAS_ADDR_SIZE);
-		port->iproto = phy->iproto;
-		port->tproto = phy->tproto;
-		port->oob_mode = phy->oob_mode;
-		port->linkrate = phy->linkrate;
-	} else
-		port->linkrate = max(port->linkrate, phy->linkrate);
-	spin_unlock(&port->phy_list_lock);
 	spin_unlock_irqrestore(&sas_ha->phy_port_lock, flags);
 
 	if (!port->port) {
-- 
2.35.1


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