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[SCSI] libsas: introduce sas_work to fix sas_drain_work vs sas_queue_work

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When requeuing work to a draining workqueue the last work instance may
not be idle, so sas_queue_work() must not touch work->entry.  Introduce
sas_work with a drain_node list_head to have a private list for
collecting work deferred due to drain collision.

Fixes reports like:
  BUG: unable to handle kernel NULL pointer dereference at           (null)
  IP: [<ffffffff810410d4>] process_one_work+0x2e/0x338

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Dan Williams
2012-03-09 11:00:06 -08:00
committed by James Bottomley
parent f8fc75dc57
commit 22b9153faa
7 changed files with 83 additions and 62 deletions
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28
drivers/scsi/libsas/sas_discover.c
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@@ -205,8 +205,7 @@ void sas_notify_lldd_dev_gone(struct domain_device *dev)
static void sas_probe_devices(struct work_struct *work)
{
struct domain_device *dev, *n;
struct sas_discovery_event *ev =
container_of(work, struct sas_discovery_event, work);
struct sas_discovery_event *ev = to_sas_discovery_event(work);
struct asd_sas_port *port = ev->port;
clear_bit(DISCE_PROBE, &port->disc.pending);
@@ -291,8 +290,7 @@ static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
static void sas_destruct_devices(struct work_struct *work)
{
struct domain_device *dev, *n;
struct sas_discovery_event *ev =
container_of(work, struct sas_discovery_event, work);
struct sas_discovery_event *ev = to_sas_discovery_event(work);
struct asd_sas_port *port = ev->port;
clear_bit(DISCE_DESTRUCT, &port->disc.pending);
@@ -377,8 +375,7 @@ static void sas_discover_domain(struct work_struct *work)
{
struct domain_device *dev;
int error = 0;
struct sas_discovery_event *ev =
container_of(work, struct sas_discovery_event, work);
struct sas_discovery_event *ev = to_sas_discovery_event(work);
struct asd_sas_port *port = ev->port;
clear_bit(DISCE_DISCOVER_DOMAIN, &port->disc.pending);
@@ -437,8 +434,7 @@ static void sas_discover_domain(struct work_struct *work)
static void sas_revalidate_domain(struct work_struct *work)
{
int res = 0;
struct sas_discovery_event *ev =
container_of(work, struct sas_discovery_event, work);
struct sas_discovery_event *ev = to_sas_discovery_event(work);
struct asd_sas_port *port = ev->port;
struct sas_ha_struct *ha = port->ha;
@@ -466,21 +462,25 @@ static void sas_revalidate_domain(struct work_struct *work)
/* ---------- Events ---------- */
static void sas_chain_work(struct sas_ha_struct *ha, struct work_struct *work)
static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work *sw)
{
/* chained work is not subject to SA_HA_DRAINING or SAS_HA_REGISTERED */
scsi_queue_work(ha->core.shost, work);
/* chained work is not subject to SA_HA_DRAINING or
* SAS_HA_REGISTERED, because it is either submitted in the
* workqueue, or known to be submitted from a context that is
* not racing against draining
*/
scsi_queue_work(ha->core.shost, &sw->work);
}
static void sas_chain_event(int event, unsigned long *pending,
struct work_struct *work,
struct sas_work *sw,
struct sas_ha_struct *ha)
{
if (!test_and_set_bit(event, pending)) {
unsigned long flags;
spin_lock_irqsave(&ha->state_lock, flags);
sas_chain_work(ha, work);
sas_chain_work(ha, sw);
spin_unlock_irqrestore(&ha->state_lock, flags);
}
}
@@ -519,7 +519,7 @@ void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
disc->pending = 0;
for (i = 0; i < DISC_NUM_EVENTS; i++) {
INIT_WORK(&disc->disc_work[i].work, sas_event_fns[i]);
INIT_SAS_WORK(&disc->disc_work[i].work, sas_event_fns[i]);
disc->disc_work[i].port = port;
}
}