From 209fae14fabfd48525e5630bebbbd4ca15090c60 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 13 Jun 2011 17:39:44 -0700 Subject: 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 --- drivers/scsi/isci/request.h | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'drivers/scsi/isci/request.h') diff --git a/drivers/scsi/isci/request.h b/drivers/scsi/isci/request.h index 8de2542f081f..9bb7c36257f3 100644 --- a/drivers/scsi/isci/request.h +++ b/drivers/scsi/isci/request.h @@ -285,7 +285,6 @@ struct isci_request { struct isci_tmf *tmf_task_ptr; /* When ttype==tmf_task */ } ttype_ptr; struct isci_host *isci_host; - struct isci_remote_device *isci_device; /* For use in the requests_to_{complete|abort} lists: */ struct list_head completed_node; /* For use in the reqs_in_process list: */ @@ -681,12 +680,10 @@ static inline void isci_request_free(struct isci_host *isci_host, 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); -int isci_request_execute(struct isci_host *isci_host, - 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); /** * isci_request_unmap_sgl() - This function unmaps the DMA address of a given -- cgit v1.2.3