[SCSI] libsas: reuse the original port when hotplugging phys in wide ports (5381837f) · Commits · e / devices / android_kernel_oneplus_sm7250

There's a hotplug problem in the way libsas allocates ports: it loops over the available ports first trying to add to an existing for a wide port and otherwise allocating the next free port. This scheme only works if the port array is packed from zero, which fails if a port gets hot unplugged and the array becomes sparse. In that case, a new port is formed even if there's a wide port it should be part of. Fix this by creating two loops over all the ports: the first to see if the phy should be part of a wide port and the second to form a new port in an empty port slot. Signed-off-by:

Tom Peng <tom_peng@usish.com> Signed-off-by:

Jack Wang <jack_wang@usish.com> Signed-off-by:

Lindar Liu <lindar_liu@usish.com> Cc: Stable Tree <stable@kernel.org> Signed-off-by:

James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/libsas/sas_port.c

+15 −4

Original line number	Diff line number	Diff line
		@@ -56,7 +56,7 @@ static void sas_form_port(struct asd_sas_phy *phy)
		}
		}

		/* find a port */
		/* see if the phy should be part of a wide port */
		spin_lock_irqsave(&sas_ha->phy_port_lock, flags);
		for (i = 0; i < sas_ha->num_phys; i++) {
		port = sas_ha->sas_port[i];
		@@ -69,12 +69,23 @@ static void sas_form_port(struct asd_sas_phy *phy)
		SAS_DPRINTK("phy%d matched wide port%d\n", phy->id,
		port->id);
		break;
		} else if ((u64 ) port->sas_addr == 0 && port->num_phys==0) {
		memcpy(port->sas_addr, phy->sas_addr, SAS_ADDR_SIZE);
		}
		spin_unlock(&port->phy_list_lock);
		}
		/* The phy does not match any existing port, create a new one */
		if (i == sas_ha->num_phys) {
		for (i = 0; i < sas_ha->num_phys; i++) {
		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);
		break;
		}
		spin_unlock(&port->phy_list_lock);
		}
		}

		if (i >= sas_ha->num_phys) {
		printk(KERN_NOTICE "%s: couldn't find a free port, bug?\n",