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scsi: add free_request callback

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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 <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Paolo Bonzini 2012-07-09 12:06:28 +02:00 committed by Gerd Hoffmann
parent 9233685597
commit 8e86b93c2b
2 changed files with 6 additions and 0 deletions
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5
hw/scsi-bus.c
View file

@ -1354,6 +1354,7 @@ static const char *scsi_command_name(uint8_t cmd)
SCSIRequest *scsi_req_ref(SCSIRequest *req)
{
assert(req->refcount > 0);
req->refcount++;
return req;
}
@ -1362,6 +1363,10 @@ 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);
}

1
hw/scsi.h
View file

@ -134,6 +134,7 @@ 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"