[PATCH v3 0/3] scsi: libsas: Handle errors in 3 functions

[PATCH v3 0/3] scsi: libsas: Handle errors in 3 functions

[Eshaan Deshmukh]

These 3 functions include several uses of BUG_ON() and lack error
management. Change all 3 functions to handle their errors in better
ways.

Eshaan Deshmukh (3):
  scsi: libsas: Handle errors in sas_ex_add_parent_port()
  scsi: libsas: Handle errors in sas_set_ex_phy()
  scsi: libsas: Handle errors in  sas_ex_discover_expander()

 drivers/scsi/libsas/sas_expander.c | 99 ++++++++++++++++++++----------
 1 file changed, 65 insertions(+), 34 deletions(-)

-- 
2.55.0

[PATCH v3 1/3] scsi: libsas: Handle errors in sas_ex_add_parent_port()

[Eshaan Deshmukh]

The function sas_ex_add_parent_port() uses BUG_ON() if sas_port_alloc()
or sas_port_add() fails. Change sas_ex_add_parent_port() to return error
codes to the caller and free the sas_port_alloc() allocation. Also
change sas_ex_discover_dev() to handle errors returned by
sas_ex_add_parent_port().

Signed-off-by: Eshaan Deshmukh <eshaan2031@icloud.com>
---
 drivers/scsi/libsas/sas_expander.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index f471ab464..f1a1417b0 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -33,19 +33,29 @@ static void sas_port_add_ex_phy(struct sas_port *port, struct ex_phy *ex_phy)
 	ex_phy->phy_state = PHY_DEVICE_DISCOVERED;
 }
 
-static void sas_ex_add_parent_port(struct domain_device *dev, int phy_id)
+static int sas_ex_add_parent_port(struct domain_device *dev, int phy_id)
 {
 	struct expander_device *ex = &dev->ex_dev;
 	struct ex_phy *ex_phy = &ex->ex_phy[phy_id];
+	int error;
 
 	if (!ex->parent_port) {
 		ex->parent_port = sas_port_alloc(&dev->rphy->dev, phy_id);
-		/* FIXME: error handling */
-		BUG_ON(!ex->parent_port);
-		BUG_ON(sas_port_add(ex->parent_port));
+		if (!ex->parent_port)
+			return -ENOMEM;
+
+		error = sas_port_add(ex->parent_port);
+		if (error) {
+			sas_port_free(ex->parent_port);
+			ex->parent_port = NULL;
+			return error;
+		}
+
 		sas_port_mark_backlink(ex->parent_port);
 	}
 	sas_port_add_ex_phy(ex->parent_port, ex_phy);
+
+	return 0;
 }
 
 /* ---------- SMP task management ---------- */
@@ -981,12 +991,14 @@ static int sas_ex_discover_dev(struct domain_device *dev, int phy_id)
 	}
 
 	/* Parent and domain coherency */
-	if (!dev->parent && sas_phy_match_port_addr(dev->port, ex_phy)) {
-		sas_ex_add_parent_port(dev, phy_id);
-		return 0;
-	}
+	if (!dev->parent && sas_phy_match_port_addr(dev->port, ex_phy))
+		return sas_ex_add_parent_port(dev, phy_id);
+
 	if (dev->parent && sas_phy_match_dev_addr(dev->parent, ex_phy)) {
-		sas_ex_add_parent_port(dev, phy_id);
+		res = sas_ex_add_parent_port(dev, phy_id);
+		if (res)
+			return res;
+
 		if (ex_phy->routing_attr == TABLE_ROUTING)
 			sas_configure_phy(dev, phy_id, dev->port->sas_addr, 1);
 		return 0;
-- 
2.55.0

[PATCH v3 2/3] scsi: libsas: Handle errors in sas_set_ex_phy()

[Eshaan Deshmukh]

The function sas_set_ex_phy() uses BUG_ON() if sas_phy_alloc() fails.
Change it to return -ENOMEM error code if that happens. Change all the
other returns in sas_set_ex_phy() to return 0 to preserve current
functionality, or to return an error. Change all uses of sas_set_ex_phy
to handle the returned error codes.

Signed-off-by: Eshaan Deshmukh <eshaan2031@icloud.com>
---
 drivers/scsi/libsas/sas_expander.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index f1a1417b0..ab6afbad3 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -207,7 +207,7 @@ static enum sas_device_type to_dev_type(struct discover_resp *dr)
 		return dr->attached_dev_type;
 }
 
-static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
+static int sas_set_ex_phy(struct domain_device *dev, int phy_id,
 			   struct smp_disc_resp *disc_resp)
 {
 	enum sas_device_type dev_type;
@@ -220,14 +220,15 @@ static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
 	struct sas_rphy *rphy = dev->rphy;
 	bool new_phy = !phy->phy;
 	char *type;
+	int error;
 
 	if (new_phy) {
 		if (WARN_ON_ONCE(test_bit(SAS_HA_ATA_EH_ACTIVE, &ha->state)))
-			return;
+			return -EBUSY;
 		phy->phy = sas_phy_alloc(&rphy->dev, phy_id);
 
-		/* FIXME: error_handling */
-		BUG_ON(!phy->phy);
+		if (!phy->phy)
+			return -ENOMEM;
 	}
 
 	switch (disc_resp->result) {
@@ -296,11 +297,14 @@ static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
 	phy->phy->enabled = (phy->linkrate != SAS_PHY_DISABLED);
 
  skip:
-	if (new_phy)
-		if (sas_phy_add(phy->phy)) {
+	if (new_phy) {
+		error = sas_phy_add(phy->phy);
+		if (error) {
 			sas_phy_free(phy->phy);
-			return;
+			phy->phy = NULL;
+			return error;
 		}
+	}
 
  out:
 	switch (phy->attached_dev_type) {
@@ -339,7 +343,7 @@ static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
 	    SAS_ADDR(phy->attached_sas_addr) != SAS_ADDR(sas_addr))
 		/* pass */;
 	else
-		return;
+		return 0;
 
 	/* if the attached device type changed and ata_eh is active,
 	 * make sure we run revalidation when eh completes (see:
@@ -353,6 +357,8 @@ static void sas_set_ex_phy(struct domain_device *dev, int phy_id,
 		 SAS_ADDR(dev->sas_addr), phy->phy_id,
 		 sas_route_char(dev, phy), phy->linkrate,
 		 SAS_ADDR(phy->attached_sas_addr), type);
+
+	return 0;
 }
 
 /* check if we have an existing attached ata device on this expander phy */
@@ -397,8 +403,8 @@ static int sas_ex_phy_discover_helper(struct domain_device *dev, u8 *disc_req,
 		pr_notice("Found loopback topology, just ignore it!\n");
 		return 0;
 	}
-	sas_set_ex_phy(dev, single, disc_resp);
-	return 0;
+
+	return sas_set_ex_phy(dev, single, disc_resp);
 }
 
 int sas_ex_phy_discover(struct domain_device *dev, int single)
@@ -2021,7 +2027,7 @@ static int sas_rediscover_dev(struct domain_device *dev, int phy_id,
 		 * the PHY info, like negotiated linkrate.
 		 */
 		if (res == 0)
-			sas_set_ex_phy(dev, phy_id, disc_resp);
+			res = sas_set_ex_phy(dev, phy_id, disc_resp);
 		goto out_free_resp;
 	} else if (SAS_ADDR(sas_addr) == SAS_ADDR(phy->attached_sas_addr) &&
 		   dev_type_flutter(type, phy->attached_dev_type)) {
-- 
2.55.0

[PATCH v3 3/3] scsi: libsas: Handle errors in sas_ex_discover_expander()

[Eshaan Deshmukh]

The function sas_ex_discover_expander() does not account for the
potential failure of sas_port_alloc() for phy->port. It also calls
BUG_ON in case sas_port_add fails for phy->port. Add a check for
phy->port after sas_port_alloc() where if it is NULL, it cleans up the
child allocated device and returns NULL. Add another check for
sas_port_add() where if it returns an error code it frees phy->port,
sets it to NULL, cleans up the child allocated device, and returns NULL.

Signed-off-by: Eshaan Deshmukh <eshaan2031@icloud.com>
---
 drivers/scsi/libsas/sas_expander.c | 41 ++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index ab6afbad3..a83493f57 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -911,7 +911,6 @@ static struct domain_device *sas_ex_discover_expander(
 	struct sas_rphy *rphy;
 	struct sas_expander_device *edev;
 	struct asd_sas_port *port;
-	int res;
 
 	if (phy->routing_attr == DIRECT_ROUTING) {
 		pr_warn("ex %016llx:%02d:D <--> ex %016llx:0x%x is not allowed\n",
@@ -925,9 +924,13 @@ static struct domain_device *sas_ex_discover_expander(
 		return NULL;
 
 	phy->port = sas_port_alloc(&parent->rphy->dev, phy_id);
-	/* FIXME: better error handling */
-	BUG_ON(sas_port_add(phy->port) != 0);
+	if (!phy->port) {
+		goto out_put_device;
+	}
 
+	if (sas_port_add(phy->port)) {
+		goto out_free_port;
+	}
 
 	switch (phy->attached_dev_type) {
 	case SAS_EDGE_EXPANDER_DEVICE:
@@ -966,19 +969,29 @@ static struct domain_device *sas_ex_discover_expander(
 	list_add_tail(&child->dev_list_node, &parent->port->dev_list);
 	spin_unlock_irq(&parent->port->dev_list_lock);
 
-	res = sas_discover_expander(child);
-	if (res) {
-		sas_rphy_delete(rphy);
-		spin_lock_irq(&parent->port->dev_list_lock);
-		list_del(&child->dev_list_node);
-		spin_unlock_irq(&parent->port->dev_list_lock);
-		sas_put_device(child);
-		sas_port_delete(phy->port);
-		phy->port = NULL;
-		return NULL;
-	}
+	if (sas_discover_expander(child))
+		goto out_delete_rphy;
+
 	list_add_tail(&child->siblings, &parent->ex_dev.children);
 	return child;
+
+out_free_port:
+	sas_port_free(phy->port);
+	phy->port = NULL;
+
+out_put_device:
+	sas_put_device(child);
+	return NULL;
+
+out_delete_rphy:
+	sas_rphy_delete(rphy);
+	spin_lock_irq(&parent->port->dev_list_lock);
+	list_del(&child->dev_list_node);
+	spin_unlock_irq(&parent->port->dev_list_lock);
+	sas_put_device(child);
+	sas_port_delete(phy->port);
+	phy->port = NULL;
+	return NULL;
 }
 
 static int sas_ex_discover_dev(struct domain_device *dev, int phy_id)
-- 
2.55.0

Re: [PATCH v3 3/3] scsi: libsas: Handle errors in sas_ex_discover_expander()

[John Garry]

On 12/08/2026 20:48, Eshaan Deshmukh wrote:
> The function sas_ex_discover_expander() does not account for the potential
> failure of sas_port_alloc() for phy->port. It also calls BUG_ON in case
> sas_port_add fails for phy->port. Add a check for phy->port after
> sas_port_alloc() where
> 
> 
> The function sas_ex_discover_expander() does not account for the
> potential failure of sas_port_alloc() for phy->port. It also calls
> BUG_ON in case sas_port_add fails for phy->port. Add a check for
> phy->port after sas_port_alloc() where if it is NULL, it cleans up the
> child allocated device and returns NULL. Add another check for
> sas_port_add() where if it returns an error code it frees phy->port,
> sets it to NULL, cleans up the child allocated device, and returns NULL.
> 
> Signed-off-by: Eshaan Deshmukh <eshaan2031@icloud.com>
> ---
>    drivers/scsi/libsas/sas_expander.c | 41 ++++++++++++++++++++----------
>    1 file changed, 27 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index ab6afbad3..a83493f57 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -911,7 +911,6 @@ static struct domain_device *sas_ex_discover_expander(
>    	struct sas_rphy *rphy;
>    	struct sas_expander_device *edev;
>    	struct asd_sas_port *port;
> -	int res;
>    
>    	if (phy->routing_attr == DIRECT_ROUTING) {
>    		pr_warn("ex %016llx:%02d:D <--> ex %016llx:0x%x is not allowed\n",
> @@ -925,9 +924,13 @@ static struct domain_device *sas_ex_discover_expander(
>    		return NULL;
>    
>    	phy->port = sas_port_alloc(&parent->rphy->dev, phy_id);
> -	/* FIXME: better error handling */
> -	BUG_ON(sas_port_add(phy->port) != 0);
> +	if (!phy->port) {

no need for {}, however please see comment further down.

> +		goto out_put_device;
> +	}
>    
> +	if (sas_port_add(phy->port)) {
> +		goto out_free_port;

ditto

> +	}
>    
>    	switch (phy->attached_dev_type) {
>    	case SAS_EDGE_EXPANDER_DEVICE:
> @@ -966,19 +969,29 @@ static struct domain_device *sas_ex_discover_expander(
>    	list_add_tail(&child->dev_list_node, &parent->port->dev_list);
>    	spin_unlock_irq(&parent->port->dev_list_lock);
>    
> -	res = sas_discover_expander(child);
> -	if (res) {
> -		sas_rphy_delete(rphy);
> -		spin_lock_irq(&parent->port->dev_list_lock);
> -		list_del(&child->dev_list_node);
> -		spin_unlock_irq(&parent->port->dev_list_lock);
> -		sas_put_device(child);
> -		sas_port_delete(phy->port);

I missed that this was a sas_port_delete() call and not sas_port_free(), 
so not common to other error paths.

So it does not look like we can make much error paths common, so maybe 
it was better as previously.

> -		phy->port = NULL;
> -		return NULL;
> -	}
> +	if (sas_discover_expander(child))
> +		goto out_delete_rphy;
> +
>    	list_add_tail(&child->siblings, &parent->ex_dev.children);
>    	return child;
> +
> +out_free_port:
> +	sas_port_free(phy->port);
> +	phy->port = NULL;
> +
> +out_put_device:
> +	sas_put_device(child);
> +	return NULL;
> +
> +out_delete_rphy:
> +	sas_rphy_delete(rphy);
> +	spin_lock_irq(&parent->port->dev_list_lock);
> +	list_del(&child->dev_list_node);
> +	spin_unlock_irq(&parent->port->dev_list_lock);
> +	sas_put_device(child);
> +	sas_port_delete(phy->port);
> +	phy->port = NULL;
> +	return NULL;
>    }
>    
>    static int sas_ex_discover_dev(struct domain_device *dev, int phy_id)
> -- 
> 2.55.0
>