Most device models have a simple lifecycle for the hba_private field and they can free it when a request is completed or cancelled. However, in some cases it may be simpler to tie the lifetime of hba_private to that of the included SCSIRequest. This patch adds a free_request callback to SCSIBusInfo that lets an HBA device model do exactly that.
Normally, device models use req->hba_private == NULL to flag requests that have been completed already. Device models that use free_request will still need to track this using a flag. This is the reason why "converting" existing HBAs to use free_request adds complexity and makes little sense. It is simply an additional convenience that is provided by the SCSI layer. USB-attached storage will be the first user. Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> --- hw/scsi-bus.c | 5 +++++ hw/scsi.h | 1 + 2 files changed, 6 insertions(+) diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c index 559a815..b9f0a5d 100644 --- a/hw/scsi-bus.c +++ b/hw/scsi-bus.c @@ -1358,6 +1358,7 @@ static const char *scsi_command_name(uint8_t cmd) SCSIRequest *scsi_req_ref(SCSIRequest *req) { + assert(req->refcount > 0); req->refcount++; return req; } @@ -1366,6 +1367,10 @@ void scsi_req_unref(SCSIRequest *req) { assert(req->refcount > 0); if (--req->refcount == 0) { + SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, req->dev->qdev.parent_bus); + if (bus->info->free_request && req->hba_private) { + bus->info->free_request(bus, req->hba_private); + } if (req->ops->free_req) { req->ops->free_req(req); } diff --git a/hw/scsi.h b/hw/scsi.h index dd1cd45..a445724 100644 --- a/hw/scsi.h +++ b/hw/scsi.h @@ -136,6 +136,7 @@ struct SCSIBusInfo { void (*save_request)(QEMUFile *f, SCSIRequest *req); void *(*load_request)(QEMUFile *f, SCSIRequest *req); + void (*free_request)(SCSIBus *bus, void *priv); }; #define TYPE_SCSI_BUS "SCSI" -- 1.7.10.2