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authorDan Williams <dan.j.williams@intel.com>2011-06-13 17:39:44 -0700
committerDan Williams <dan.j.williams@intel.com>2011-07-03 04:04:51 -0700
commit209fae14fabfd48525e5630bebbbd4ca15090c60 (patch)
treeb251b9b394b3493cc15242ea31002abcb4e9bb59 /drivers/scsi/isci/request.c
parent360b03ed178a4fe3971b0a098d8feeb53333481b (diff)
isci: atomic device lookup and reference counting
We have unsafe references to remote devices that are notified to disappear at lldd_dev_gone. In order to clean this up we need a single canonical source for device lookups and stable references once a lookup succeeds. Towards that end guarantee that domain_device.lldd_dev is NULL as soon as we start the process of stopping a device. Any code path that wants to safely lookup a remote device must do so through task->dev->lldd_dev (isci_lookup_device()). For in-flight references outside of scic_lock we need reference counting to ensure that the device is not recycled before we are done with it. Simplify device back references to just scic_sds_request.target_device which is now the only permissible internal reference that is maintained relative to the reference count. There were two occasions where we wanted new i/o's to be treated as SAS_TASK_UNDELIVERED but where the domain_dev->lldd_dev link is still intact. Introduce a 'gone' flag to prevent i/o while waiting for libsas to take action on the port down event. One 'core' leftover is that we currently call scic_remote_device_destruct() from isci_remote_device_deconstruct() which is called when the 'core' says the device is stopped. It would be more natural for the final put to trigger isci_remote_device_deconstruct() but this implementation is deferred as it requires other changes. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/scsi/isci/request.c')
-rw-r--r--drivers/scsi/isci/request.c60
1 files changed, 21 insertions, 39 deletions
diff --git a/drivers/scsi/isci/request.c b/drivers/scsi/isci/request.c
index f0813d076c50..fd6314abeb0b 100644
--- a/drivers/scsi/isci/request.c
+++ b/drivers/scsi/isci/request.c
@@ -2313,7 +2313,7 @@ static void isci_request_set_open_reject_status(
* none.
*/
static void isci_request_handle_controller_specific_errors(
- struct isci_remote_device *isci_device,
+ struct isci_remote_device *idev,
struct isci_request *request,
struct sas_task *task,
enum service_response *response_ptr,
@@ -2353,8 +2353,7 @@ static void isci_request_handle_controller_specific_errors(
* that we ignore the quiesce state, since we are
* concerned about the actual device state.
*/
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
*status_ptr = SAS_DEVICE_UNKNOWN;
else
*status_ptr = SAS_ABORTED_TASK;
@@ -2367,8 +2366,7 @@ static void isci_request_handle_controller_specific_errors(
/* Task in the target is not done. */
*response_ptr = SAS_TASK_UNDELIVERED;
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
*status_ptr = SAS_DEVICE_UNKNOWN;
else
*status_ptr = SAM_STAT_TASK_ABORTED;
@@ -2399,8 +2397,7 @@ static void isci_request_handle_controller_specific_errors(
* that we ignore the quiesce state, since we are
* concerned about the actual device state.
*/
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
*status_ptr = SAS_DEVICE_UNKNOWN;
else
*status_ptr = SAS_ABORTED_TASK;
@@ -2629,7 +2626,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
struct ssp_response_iu *resp_iu;
void *resp_buf;
unsigned long task_flags;
- struct isci_remote_device *isci_device = request->isci_device;
+ struct isci_remote_device *idev = isci_lookup_device(task->dev);
enum service_response response = SAS_TASK_UNDELIVERED;
enum exec_status status = SAS_ABORTED_TASK;
enum isci_request_status request_status;
@@ -2672,9 +2669,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
* that we ignore the quiesce state, since we are
* concerned about the actual device state.
*/
- if ((isci_device->status == isci_stopping)
- || (isci_device->status == isci_stopped)
- )
+ if (!idev)
status = SAS_DEVICE_UNKNOWN;
else
status = SAS_ABORTED_TASK;
@@ -2697,8 +2692,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
request->complete_in_target = true;
response = SAS_TASK_UNDELIVERED;
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
/* The device has been /is being stopped. Note that
* we ignore the quiesce state, since we are
* concerned about the actual device state.
@@ -2728,8 +2722,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
* that we ignore the quiesce state, since we are
* concerned about the actual device state.
*/
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
status = SAS_DEVICE_UNKNOWN;
else
status = SAS_ABORTED_TASK;
@@ -2861,8 +2854,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
* that we ignore the quiesce state, since we are
* concerned about the actual device state.
*/
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
status = SAS_DEVICE_UNKNOWN;
else
status = SAS_ABORTED_TASK;
@@ -2873,7 +2865,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
case SCI_FAILURE_CONTROLLER_SPECIFIC_IO_ERR:
isci_request_handle_controller_specific_errors(
- isci_device, request, task, &response, &status,
+ idev, request, task, &response, &status,
&complete_to_host);
break;
@@ -2902,8 +2894,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
/* Fail the I/O so it can be retried. */
response = SAS_TASK_UNDELIVERED;
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
status = SAS_DEVICE_UNKNOWN;
else
status = SAS_ABORTED_TASK;
@@ -2926,8 +2917,7 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
* that we ignore the quiesce state, since we are
* concerned about the actual device state.
*/
- if ((isci_device->status == isci_stopping) ||
- (isci_device->status == isci_stopped))
+ if (!idev)
status = SAS_DEVICE_UNKNOWN;
else
status = SAS_ABORTED_TASK;
@@ -2953,8 +2943,10 @@ static void isci_request_io_request_complete(struct isci_host *isci_host,
/* complete the io request to the core. */
scic_controller_complete_io(&isci_host->sci,
- &isci_device->sci,
+ request->sci.target_device,
&request->sci);
+ isci_put_device(idev);
+
/* set terminated handle so it cannot be completed or
* terminated again, and to cause any calls into abort
* task to recognize the already completed case.
@@ -3511,7 +3503,6 @@ static enum sci_status isci_io_request_build(
}
static struct isci_request *isci_request_alloc_core(struct isci_host *ihost,
- struct isci_remote_device *idev,
gfp_t gfp_flags)
{
dma_addr_t handle;
@@ -3528,7 +3519,6 @@ static struct isci_request *isci_request_alloc_core(struct isci_host *ihost,
spin_lock_init(&ireq->state_lock);
ireq->request_daddr = handle;
ireq->isci_host = ihost;
- ireq->isci_device = idev;
ireq->io_request_completion = NULL;
ireq->terminated = false;
@@ -3546,12 +3536,11 @@ static struct isci_request *isci_request_alloc_core(struct isci_host *ihost,
static struct isci_request *isci_request_alloc_io(struct isci_host *ihost,
struct sas_task *task,
- struct isci_remote_device *idev,
gfp_t gfp_flags)
{
struct isci_request *ireq;
- ireq = isci_request_alloc_core(ihost, idev, gfp_flags);
+ ireq = isci_request_alloc_core(ihost, gfp_flags);
if (ireq) {
ireq->ttype_ptr.io_task_ptr = task;
ireq->ttype = io_task;
@@ -3562,12 +3551,11 @@ static struct isci_request *isci_request_alloc_io(struct isci_host *ihost,
struct isci_request *isci_request_alloc_tmf(struct isci_host *ihost,
struct isci_tmf *isci_tmf,
- struct isci_remote_device *idev,
gfp_t gfp_flags)
{
struct isci_request *ireq;
- ireq = isci_request_alloc_core(ihost, idev, gfp_flags);
+ ireq = isci_request_alloc_core(ihost, gfp_flags);
if (ireq) {
ireq->ttype_ptr.tmf_task_ptr = isci_tmf;
ireq->ttype = tmf_task;
@@ -3575,21 +3563,16 @@ struct isci_request *isci_request_alloc_tmf(struct isci_host *ihost,
return ireq;
}
-int isci_request_execute(struct isci_host *ihost, struct sas_task *task,
- gfp_t gfp_flags)
+int isci_request_execute(struct isci_host *ihost, struct isci_remote_device *idev,
+ struct sas_task *task, gfp_t gfp_flags)
{
enum sci_status status = SCI_FAILURE_UNSUPPORTED_PROTOCOL;
- struct scic_sds_remote_device *sci_dev;
- struct isci_remote_device *idev;
struct isci_request *ireq;
unsigned long flags;
int ret = 0;
- idev = task->dev->lldd_dev;
- sci_dev = &idev->sci;
-
/* do common allocation and init of request object. */
- ireq = isci_request_alloc_io(ihost, task, idev, gfp_flags);
+ ireq = isci_request_alloc_io(ihost, task, gfp_flags);
if (!ireq)
goto out;
@@ -3605,8 +3588,7 @@ int isci_request_execute(struct isci_host *ihost, struct sas_task *task,
spin_lock_irqsave(&ihost->scic_lock, flags);
/* send the request, let the core assign the IO TAG. */
- status = scic_controller_start_io(&ihost->sci, sci_dev,
- &ireq->sci,
+ status = scic_controller_start_io(&ihost->sci, &idev->sci, &ireq->sci,
SCI_CONTROLLER_INVALID_IO_TAG);
if (status != SCI_SUCCESS &&
status != SCI_FAILURE_REMOTE_DEVICE_RESET_REQUIRED) {

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