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Subject[patch 04/28] SCSI: libsas: reuse the original port when hotplugging phys in wide ports
2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Tom Peng <tom_peng@usish.com>

commit 5381837f125cc62ad703fbcdfcd7566fc81fd404 upstream.

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>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/scsi/libsas/sas_port.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -56,7 +56,7 @@ static void sas_form_port(struct asd_sas
}
}

- /* 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
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);
- break;
}
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",



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