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[Qemu-devel] [PATCH] scsi: add free_request callback
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH] scsi: add free_request callback |
Date: |
Mon, 9 Jul 2012 12:06:28 +0200 |
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 <address@hidden>
---
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
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