[PATCH 15/17] scsi_dh_alua: Recheck state on unit attention

Hannes Reinecke
2015-05-04T12:42:43Z

When we receive a unit attention code of 'ALUA state changed'
we should recheck the state, as it might be due to an implicit
ALUA state transition.
At the same time a workqueue item might already be queued, which
should be started immediately to avoid any delays.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 65 +++++++++++++++++-------------
1 file changed, 36 insertions(+), 29 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 142c95b..cf83005 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -69,6 +69,7 @@
/* State machine flags */
#define ALUA_PG_RUN_RTPG 0x10
#define ALUA_PG_RUN_STPG 0x20
+#define ALUA_PG_RUNNING 0x40

static LIST_HEAD(port_group_list);
@@ -119,7 +120,7 @@ struct alua_queue_data {
static char print_alua_state(int);
static int alua_check_sense(struct scsi_device *, struct scsi_sense_hdr *);
static void alua_rtpg_work(struct work_struct *work);
-static void alua_check(struct scsi_device *sdev);
+static void alua_check(struct scsi_device *sdev, bool force);

static int realloc_buffer(struct alua_port_group *pg, unsigned len)
{
@@ -487,7 +488,7 @@ static char print_alua_state(int state)
}

static int alua_check_sense(struct scsi_device *sdev,
- struct scsi_sense_hdr *sense_hdr)
+ struct scsi_sense_hdr *sense_hdr)
{
switch (sense_hdr->sense_key) {
case NOT_READY:
@@ -496,36 +497,34 @@ static int alua_check_sense(struct scsi_device *sdev,
* LUN Not Accessible - ALUA state transition
* Kickoff worker to update internal state.
*/
- alua_check(sdev);
- return ADD_TO_MLQUEUE;
+ alua_check(sdev, false);
+ return NEEDS_RETRY;
}
break;
case UNIT_ATTENTION:
- if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
- /*
- * Power On, Reset, or Bus Device Reset, just retry.
- */
- return ADD_TO_MLQUEUE;
- if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
- /*
- * Device internal reset
- */
- return ADD_TO_MLQUEUE;
- if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
+ if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
/*
- * Mode parameter changed
+ * Power On, Reset, or Bus Device Reset.
+ * Might have obscured a state transition,
+ * so schedule a recheck.
*/
+ alua_check(sdev, true);
return ADD_TO_MLQUEUE;
- if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
+ }
+ if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
/*
* ALUA state changed
*/
+ alua_check(sdev, true);
return ADD_TO_MLQUEUE;
- if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)
+ }
+ if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
/*
* Implicit ALUA state transition failed
*/
+ alua_check(sdev, true);
return ADD_TO_MLQUEUE;
+ }
break;
}

@@ -589,7 +588,6 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
goto retry;
}

- err = alua_check_sense(sdev, &sense_hdr);
if (sense_hdr.sense_key == UNIT_ATTENTION)
err = ADD_TO_MLQUEUE;
if (err == ADD_TO_MLQUEUE &&
@@ -744,7 +742,6 @@ static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
/* Retry RTPG */
return err;
}
- err = alua_check_sense(sdev, &sense_hdr);
sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
ALUA_DH_NAME);
scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
@@ -771,15 +768,18 @@ static void alua_rtpg_work(struct work_struct *work)
spin_unlock_irqrestore(&pg->rtpg_lock, flags);
return;
}
+ pg->flags |= ALUA_PG_RUNNING;
if (pg->flags & ALUA_PG_RUN_RTPG) {
spin_unlock_irqrestore(&pg->rtpg_lock, flags);
err = alua_rtpg(sdev, pg);
+ spin_lock_irqsave(&pg->rtpg_lock, flags);
if (err == SCSI_DH_RETRY) {
+ pg->flags &= ~ALUA_PG_RUNNING;
+ spin_unlock_irqrestore(&pg->rtpg_lock, flags);
queue_delayed_work(scsidh_aluad, &pg->rtpg_work,
pg->interval * HZ);
return;
}
- spin_lock_irqsave(&pg->rtpg_lock, flags);
pg->flags &= ~ALUA_PG_RUN_RTPG;
if (err != SCSI_DH_OK)
pg->flags &= ~ALUA_PG_RUN_STPG;
@@ -792,6 +792,7 @@ static void alua_rtpg_work(struct work_struct *work)
if (err == SCSI_DH_RETRY) {
pg->flags |= ALUA_PG_RUN_RTPG;
pg->interval = 0;
+ pg->flags &= ~ALUA_PG_RUNNING;
spin_unlock_irqrestore(&pg->rtpg_lock, flags);
queue_delayed_work(scsidh_aluad, &pg->rtpg_work,
msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS));
@@ -809,13 +810,16 @@ static void alua_rtpg_work(struct work_struct *work)
qdata->callback_fn(qdata->callback_data, err);
kfree(qdata);
}
+ spin_lock_irqsave(&pg->rtpg_lock, flags);
+ pg->flags &= ~ALUA_PG_RUNNING;
+ spin_unlock_irqrestore(&pg->rtpg_lock, flags);
kref_put(&pg->kref, release_port_group);
scsi_device_put(sdev);
}

static void alua_rtpg_queue(struct alua_port_group *pg,
struct scsi_device *sdev,
- struct alua_queue_data *qdata)
+ struct alua_queue_data *qdata, bool force)
{
int start_queue = 0;
unsigned long flags;
@@ -836,12 +840,15 @@ static void alua_rtpg_queue(struct alua_port_group *pg,
pg->rtpg_sdev = sdev;
scsi_device_get(sdev);
start_queue = 1;
- }
+ } else if (!(pg->flags & ALUA_PG_RUNNING) && force)
+ start_queue = 1;
+
spin_unlock_irqrestore(&pg->rtpg_lock, flags);

if (start_queue)
- queue_delayed_work(scsidh_aluad, &pg->rtpg_work,
- msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS));
+ mod_delayed_work(scsidh_aluad, &pg->rtpg_work,
+ msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS));
+
kref_put(&pg->kref, release_port_group);
}

@@ -874,7 +881,7 @@ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
complete(&h->init_complete);
if (pg) {
pg->expiry = 0;
- alua_rtpg_queue(pg, sdev, NULL);
+ alua_rtpg_queue(pg, sdev, NULL, true);
kref_put(&pg->kref, release_port_group);
}
return h->error;
@@ -986,7 +993,7 @@ static int alua_activate(struct scsi_device *sdev,
pg->flags |= ALUA_OPTIMIZE_STPG;
spin_unlock_irqrestore(&pg->rtpg_lock, flags);
}
- alua_rtpg_queue(pg, sdev, qdata);
+ alua_rtpg_queue(pg, sdev, qdata, true);
kref_put(&pg->kref, release_port_group);
out:
if (fn)
@@ -1000,7 +1007,7 @@ out:
*
* Check the device status
*/
-static void alua_check(struct scsi_device *sdev)
+static void alua_check(struct scsi_device *sdev, bool force)
{
struct alua_dh_data *h = sdev->handler_data;
struct alua_port_group *pg;
@@ -1010,7 +1017,7 @@ static void alua_check(struct scsi_device *sdev)
if (pg) {
kref_get(&pg->kref);
rcu_read_unlock();
- alua_rtpg_queue(pg, sdev, NULL);
+ alua_rtpg_queue(pg, sdev, NULL, force);
kref_put(&pg->kref, release_port_group);
} else
rcu_read_unlock();
--
1.8.5.2