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[SCSI] zfcp: Allow running unit/LUN shutdown without acquiring reference
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With the change for the LUN data to be part of the scsi_device, the
slave_destroy callback will be the final call to the
zfcp_erp_unit_shutdown function. The erp tries to acquire a reference
to run the action asynchronously and fail, if it cannot get the
reference. But calling scsi_device_get from slave_destroy will fail,
because the scsi_device is already in the state SDEV_DEL.

Introduce a new call into the zfcp erp to solve this: The function
zfcp_erp_unit_shutdown_wait will close the LUN and wait for the erp to
finish without acquiring an additional reference. The wait allows to
omit the reference; the caller waiting for the erp to finish already
has a reference that holds the struct in place.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
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Christof Schmitt authored and James Bottomley committed Sep 17, 2010
1 parent e4b9857 commit fdbd1c5
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Showing 2 changed files with 63 additions and 36 deletions.
98 changes: 62 additions & 36 deletions drivers/s390/scsi/zfcp_erp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ enum zfcp_erp_act_flags {
ZFCP_STATUS_ERP_DISMISSING = 0x00100000,
ZFCP_STATUS_ERP_DISMISSED = 0x00200000,
ZFCP_STATUS_ERP_LOWMEM = 0x00400000,
ZFCP_STATUS_ERP_NO_REF = 0x00800000,
};

enum zfcp_erp_steps {
Expand Down Expand Up @@ -169,22 +170,22 @@ static int zfcp_erp_required_act(int want, struct zfcp_adapter *adapter,
return need;
}

static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
static struct zfcp_erp_action *zfcp_erp_setup_act(int need, u32 act_status,
struct zfcp_adapter *adapter,
struct zfcp_port *port,
struct zfcp_unit *unit)
{
struct zfcp_erp_action *erp_action;
u32 status = 0;

switch (need) {
case ZFCP_ERP_ACTION_REOPEN_UNIT:
if (!get_device(&unit->dev))
return NULL;
if (!(act_status & ZFCP_STATUS_ERP_NO_REF))
if (!get_device(&unit->dev))
return NULL;
atomic_set_mask(ZFCP_STATUS_COMMON_ERP_INUSE, &unit->status);
erp_action = &unit->erp_action;
if (!(atomic_read(&unit->status) & ZFCP_STATUS_COMMON_RUNNING))
status = ZFCP_STATUS_ERP_CLOSE_ONLY;
act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
break;

case ZFCP_ERP_ACTION_REOPEN_PORT:
Expand All @@ -195,7 +196,7 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
atomic_set_mask(ZFCP_STATUS_COMMON_ERP_INUSE, &port->status);
erp_action = &port->erp_action;
if (!(atomic_read(&port->status) & ZFCP_STATUS_COMMON_RUNNING))
status = ZFCP_STATUS_ERP_CLOSE_ONLY;
act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
break;

case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
Expand All @@ -205,7 +206,7 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
erp_action = &adapter->erp_action;
if (!(atomic_read(&adapter->status) &
ZFCP_STATUS_COMMON_RUNNING))
status = ZFCP_STATUS_ERP_CLOSE_ONLY;
act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
break;

default:
Expand All @@ -217,14 +218,15 @@ static struct zfcp_erp_action *zfcp_erp_setup_act(int need,
erp_action->port = port;
erp_action->unit = unit;
erp_action->action = need;
erp_action->status = status;
erp_action->status = act_status;

return erp_action;
}

static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter,
struct zfcp_port *port,
struct zfcp_unit *unit, char *id, void *ref)
struct zfcp_unit *unit, char *id, void *ref,
u32 act_status)
{
int retval = 1, need;
struct zfcp_erp_action *act = NULL;
Expand All @@ -236,10 +238,10 @@ static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter,
if (!need)
goto out;

atomic_set_mask(ZFCP_STATUS_ADAPTER_ERP_PENDING, &adapter->status);
act = zfcp_erp_setup_act(need, adapter, port, unit);
act = zfcp_erp_setup_act(need, act_status, adapter, port, unit);
if (!act)
goto out;
atomic_set_mask(ZFCP_STATUS_ADAPTER_ERP_PENDING, &adapter->status);
++adapter->erp_total_count;
list_add_tail(&act->list, &adapter->erp_ready_head);
wake_up(&adapter->erp_ready_wq);
Expand All @@ -262,7 +264,7 @@ static int _zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter,
return -EIO;
}
return zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_ADAPTER,
adapter, NULL, NULL, id, ref);
adapter, NULL, NULL, id, ref, 0);
}

/**
Expand All @@ -285,7 +287,7 @@ void zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter, int clear,
zfcp_erp_adapter_failed(adapter, "erareo1", NULL);
else
zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_ADAPTER, adapter,
NULL, NULL, id, ref);
NULL, NULL, id, ref, 0);
write_unlock_irqrestore(&adapter->erp_lock, flags);
}

Expand Down Expand Up @@ -317,20 +319,6 @@ void zfcp_erp_port_shutdown(struct zfcp_port *port, int clear, char *id,
zfcp_erp_port_reopen(port, clear | flags, id, ref);
}

/**
* zfcp_erp_unit_shutdown - Shutdown unit
* @unit: Unit to shut down.
* @clear: Status flags to clear.
* @id: Id for debug trace event.
* @ref: Reference for debug trace event.
*/
void zfcp_erp_unit_shutdown(struct zfcp_unit *unit, int clear, char *id,
void *ref)
{
int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
zfcp_erp_unit_reopen(unit, clear | flags, id, ref);
}

static void zfcp_erp_port_block(struct zfcp_port *port, int clear)
{
zfcp_erp_modify_port_status(port, "erpblk1", NULL,
Expand All @@ -348,7 +336,7 @@ static void _zfcp_erp_port_forced_reopen(struct zfcp_port *port,
return;

zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_PORT_FORCED,
port->adapter, port, NULL, id, ref);
port->adapter, port, NULL, id, ref, 0);
}

/**
Expand Down Expand Up @@ -381,7 +369,7 @@ static int _zfcp_erp_port_reopen(struct zfcp_port *port, int clear, char *id,
}

return zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_PORT,
port->adapter, port, NULL, id, ref);
port->adapter, port, NULL, id, ref, 0);
}

/**
Expand Down Expand Up @@ -412,7 +400,7 @@ static void zfcp_erp_unit_block(struct zfcp_unit *unit, int clear_mask)
}

static void _zfcp_erp_unit_reopen(struct zfcp_unit *unit, int clear, char *id,
void *ref)
void *ref, u32 act_status)
{
struct zfcp_adapter *adapter = unit->port->adapter;

Expand All @@ -422,7 +410,7 @@ static void _zfcp_erp_unit_reopen(struct zfcp_unit *unit, int clear, char *id,
return;

zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_UNIT,
adapter, unit->port, unit, id, ref);
adapter, unit->port, unit, id, ref, act_status);
}

/**
Expand All @@ -439,8 +427,45 @@ void zfcp_erp_unit_reopen(struct zfcp_unit *unit, int clear, char *id,
struct zfcp_adapter *adapter = port->adapter;

write_lock_irqsave(&adapter->erp_lock, flags);
_zfcp_erp_unit_reopen(unit, clear, id, ref);
_zfcp_erp_unit_reopen(unit, clear, id, ref, 0);
write_unlock_irqrestore(&adapter->erp_lock, flags);
}

/**
* zfcp_erp_unit_shutdown - Shutdown unit
* @unit: Unit to shut down.
* @clear: Status flags to clear.
* @id: Id for debug trace event.
* @ref: Reference for debug trace event.
*/
void zfcp_erp_unit_shutdown(struct zfcp_unit *unit, int clear, char *id,
void *ref)
{
int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
zfcp_erp_unit_reopen(unit, clear | flags, id, ref);
}

/**
* zfcp_erp_unit_shutdown_wait - Shutdown unit and wait for erp completion
* @unit: Unit to shut down.
* @id: Id for debug trace event.
*
* Do not acquire a reference for the unit when creating the ERP
* action. It is safe, because this function waits for the ERP to
* complete first.
*/
void zfcp_erp_unit_shutdown_wait(struct zfcp_unit *unit, char *id)
{
unsigned long flags;
struct zfcp_port *port = unit->port;
struct zfcp_adapter *adapter = port->adapter;
int clear = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;

write_lock_irqsave(&adapter->erp_lock, flags);
_zfcp_erp_unit_reopen(unit, clear, id, NULL, ZFCP_STATUS_ERP_NO_REF);
write_unlock_irqrestore(&adapter->erp_lock, flags);

zfcp_erp_wait(adapter);
}

static int status_change_set(unsigned long mask, atomic_t *status)
Expand Down Expand Up @@ -566,7 +591,7 @@ static void _zfcp_erp_unit_reopen_all(struct zfcp_port *port, int clear,

read_lock(&port->unit_list_lock);
list_for_each_entry(unit, &port->unit_list, list)
_zfcp_erp_unit_reopen(unit, clear, id, ref);
_zfcp_erp_unit_reopen(unit, clear, id, ref, 0);
read_unlock(&port->unit_list_lock);
}

Expand All @@ -583,7 +608,7 @@ static void zfcp_erp_strategy_followup_failed(struct zfcp_erp_action *act)
_zfcp_erp_port_reopen(act->port, 0, "ersff_3", NULL);
break;
case ZFCP_ERP_ACTION_REOPEN_UNIT:
_zfcp_erp_unit_reopen(act->unit, 0, "ersff_4", NULL);
_zfcp_erp_unit_reopen(act->unit, 0, "ersff_4", NULL, 0);
break;
}
}
Expand Down Expand Up @@ -1143,7 +1168,7 @@ static int zfcp_erp_strategy_statechange(struct zfcp_erp_action *act, int ret)
if (zfcp_erp_strat_change_det(&unit->status, erp_status)) {
_zfcp_erp_unit_reopen(unit,
ZFCP_STATUS_COMMON_ERP_FAILED,
"ersscg3", NULL);
"ersscg3", NULL, 0);
return ZFCP_ERP_EXIT;
}
break;
Expand Down Expand Up @@ -1191,7 +1216,8 @@ static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act, int result)

switch (act->action) {
case ZFCP_ERP_ACTION_REOPEN_UNIT:
put_device(&unit->dev);
if (!(act->status & ZFCP_STATUS_ERP_NO_REF))
put_device(&unit->dev);
break;

case ZFCP_ERP_ACTION_REOPEN_PORT:
Expand Down
1 change: 1 addition & 0 deletions drivers/s390/scsi/zfcp_ext.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,7 @@ extern void zfcp_erp_modify_unit_status(struct zfcp_unit *, char *, void *, u32,
int);
extern void zfcp_erp_unit_reopen(struct zfcp_unit *, int, char *, void *);
extern void zfcp_erp_unit_shutdown(struct zfcp_unit *, int, char *, void *);
extern void zfcp_erp_unit_shutdown_wait(struct zfcp_unit *, char *);
extern void zfcp_erp_unit_failed(struct zfcp_unit *, char *, void *);
extern int zfcp_erp_thread_setup(struct zfcp_adapter *);
extern void zfcp_erp_thread_kill(struct zfcp_adapter *);
Expand Down

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