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[Qemu-devel] [PATCH v5 06/25] scsi: reference-count requests
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH v5 06/25] scsi: reference-count requests |
Date: |
Thu, 26 May 2011 12:56:32 +0200 |
With the next patch, a device may hold SCSIRequest for an indefinite
time. Split a rather big patch, and protect against access errors,
by reference counting them.
There is some ugliness in scsi_send_command implementation due to
the need to unref the request when it fails. This will go away
with the next patches, which move the unref'ing to the devices.
Signed-off-by: Paolo Bonzini <address@hidden>
Cc: Christoph Hellwig <address@hidden>
---
hw/scsi-bus.c | 29 ++++++++++++++++++++++-------
hw/scsi-disk.c | 23 +++++++++++++++--------
hw/scsi-generic.c | 24 ++++++++++++++++--------
hw/scsi.h | 5 +++++
4 files changed, 58 insertions(+), 23 deletions(-)
diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c
index 1850a87..20d6c51 100644
--- a/hw/scsi-bus.c
+++ b/hw/scsi-bus.c
@@ -136,6 +136,8 @@ SCSIRequest *scsi_req_alloc(size_t size, SCSIDevice *d,
uint32_t tag, uint32_t l
SCSIRequest *req;
req = qemu_mallocz(size);
+ /* Two references: one is passed back to the HBA, one is in d->requests.
*/
+ req->refcount = 2;
req->bus = scsi_bus_from_device(d);
req->dev = d;
req->tag = tag;
@@ -159,21 +161,16 @@ SCSIRequest *scsi_req_find(SCSIDevice *d, uint32_t tag)
return NULL;
}
-static void scsi_req_dequeue(SCSIRequest *req)
+void scsi_req_dequeue(SCSIRequest *req)
{
trace_scsi_req_dequeue(req->dev->id, req->lun, req->tag);
if (req->enqueued) {
QTAILQ_REMOVE(&req->dev->requests, req, next);
req->enqueued = false;
+ scsi_req_unref(req);
}
}
-void scsi_req_free(SCSIRequest *req)
-{
- scsi_req_dequeue(req);
- qemu_free(req);
-}
-
static int scsi_req_length(SCSIRequest *req, uint8_t *cmd)
{
switch (cmd[0] >> 5) {
@@ -495,6 +492,22 @@ static const char *scsi_command_name(uint8_t cmd)
return names[cmd];
}
+SCSIRequest *scsi_req_ref(SCSIRequest *req)
+{
+ req->refcount++;
+ return req;
+}
+
+void scsi_req_unref(SCSIRequest *req)
+{
+ if (--req->refcount == 0) {
+ if (req->dev->info->free_req) {
+ req->dev->info->free_req(req);
+ }
+ qemu_free(req);
+ }
+}
+
/* Called by the devices when data is ready for the HBA. The HBA should
start a DMA operation to read or fill the device's data buffer.
Once it completes, calling one of req->dev->info->read_data or
@@ -537,10 +550,12 @@ void scsi_req_print(SCSIRequest *req)
void scsi_req_complete(SCSIRequest *req)
{
assert(req->status != -1);
+ scsi_req_ref(req);
scsi_req_dequeue(req);
req->bus->ops->complete(req->bus, SCSI_REASON_DONE,
req->tag,
req->status);
+ scsi_req_unref(req);
}
static char *scsibus_get_fw_dev_path(DeviceState *dev)
diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 741cf39..87d7b93 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -98,10 +98,11 @@ static SCSIDiskReq *scsi_new_request(SCSIDiskState *s,
uint32_t tag,
return r;
}
-static void scsi_remove_request(SCSIDiskReq *r)
+static void scsi_free_request(SCSIRequest *req)
{
+ SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);
+
qemu_vfree(r->iov.iov_base);
- scsi_req_free(&r->req);
}
static SCSIDiskReq *scsi_find_request(SCSIDiskState *s, uint32_t tag)
@@ -134,7 +135,6 @@ static void scsi_command_complete(SCSIDiskReq *r, int
status, int sense)
r->req.tag, status, sense);
scsi_req_set_status(r, status, sense);
scsi_req_complete(&r->req);
- scsi_remove_request(r);
}
/* Cancel a pending data transfer. */
@@ -148,7 +148,7 @@ static void scsi_cancel_io(SCSIDevice *d, uint32_t tag)
if (r->req.aiocb)
bdrv_aio_cancel(r->req.aiocb);
r->req.aiocb = NULL;
- scsi_remove_request(r);
+ scsi_req_dequeue(&r->req);
}
}
@@ -1033,7 +1033,7 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
uint8_t *buf, int lun)
{
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, d);
- uint32_t len;
+ int32_t len;
int is_write;
uint8_t command;
uint8_t *outbuf;
@@ -1095,6 +1095,7 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
case REZERO_UNIT:
rc = scsi_disk_emulate_command(r, outbuf);
if (rc < 0) {
+ scsi_req_unref(&r->req);
return 0;
}
@@ -1181,9 +1182,11 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
DPRINTF("Unknown SCSI command (%2.2x)\n", buf[0]);
fail:
scsi_command_complete(r, CHECK_CONDITION, ILLEGAL_REQUEST);
+ scsi_req_unref(&r->req);
return 0;
illegal_lba:
scsi_command_complete(r, CHECK_CONDITION, HARDWARE_ERROR);
+ scsi_req_unref(&r->req);
return 0;
}
if (r->sector_count == 0 && r->iov.iov_len == 0) {
@@ -1191,12 +1194,13 @@ static int32_t scsi_send_command(SCSIDevice *d,
uint32_t tag,
}
len = r->sector_count * 512 + r->iov.iov_len;
if (is_write) {
- return -len;
+ len = -len;
} else {
if (!r->sector_count)
r->sector_count = -1;
- return len;
}
+ scsi_req_unref(&r->req);
+ return len;
}
static void scsi_disk_purge_requests(SCSIDiskState *s)
@@ -1208,7 +1212,7 @@ static void scsi_disk_purge_requests(SCSIDiskState *s)
if (r->req.aiocb) {
bdrv_aio_cancel(r->req.aiocb);
}
- scsi_remove_request(r);
+ scsi_req_dequeue(&r->req);
}
}
@@ -1321,6 +1325,7 @@ static SCSIDeviceInfo scsi_disk_info[] = {
.qdev.reset = scsi_disk_reset,
.init = scsi_hd_initfn,
.destroy = scsi_destroy,
+ .free_req = scsi_free_request,
.send_command = scsi_send_command,
.read_data = scsi_read_data,
.write_data = scsi_write_data,
@@ -1339,6 +1344,7 @@ static SCSIDeviceInfo scsi_disk_info[] = {
.qdev.reset = scsi_disk_reset,
.init = scsi_cd_initfn,
.destroy = scsi_destroy,
+ .free_req = scsi_free_request,
.send_command = scsi_send_command,
.read_data = scsi_read_data,
.write_data = scsi_write_data,
@@ -1356,6 +1362,7 @@ static SCSIDeviceInfo scsi_disk_info[] = {
.qdev.reset = scsi_disk_reset,
.init = scsi_disk_initfn,
.destroy = scsi_destroy,
+ .free_req = scsi_free_request,
.send_command = scsi_send_command,
.read_data = scsi_read_data,
.write_data = scsi_write_data,
diff --git a/hw/scsi-generic.c b/hw/scsi-generic.c
index bd09983..06e9dfe 100644
--- a/hw/scsi-generic.c
+++ b/hw/scsi-generic.c
@@ -74,10 +74,11 @@ static SCSIGenericReq *scsi_new_request(SCSIDevice *d,
uint32_t tag, uint32_t lu
return DO_UPCAST(SCSIGenericReq, req, req);
}
-static void scsi_remove_request(SCSIGenericReq *r)
+static void scsi_free_request(SCSIRequest *req)
{
+ SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+
qemu_free(r->buf);
- scsi_req_free(&r->req);
}
static SCSIGenericReq *scsi_find_request(SCSIGenericState *s, uint32_t tag)
@@ -113,7 +114,6 @@ static void scsi_command_complete(void *opaque, int ret)
r, r->req.tag, r->req.status);
scsi_req_complete(&r->req);
- scsi_remove_request(r);
}
/* Cancel a pending data transfer. */
@@ -128,7 +128,7 @@ static void scsi_cancel_io(SCSIDevice *d, uint32_t tag)
if (r->req.aiocb)
bdrv_aio_cancel(r->req.aiocb);
r->req.aiocb = NULL;
- scsi_remove_request(r);
+ scsi_req_dequeue(&r->req);
}
}
@@ -323,6 +323,7 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
SCSIGenericReq *r;
SCSIBus *bus;
int ret;
+ int32_t len;
if (cmd[0] != REQUEST_SENSE &&
(lun != s->lun || (cmd[1] >> 5) != s->lun)) {
@@ -351,7 +352,8 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
if (-1 == scsi_req_parse(&r->req, cmd)) {
BADF("Unsupported command length, command %x\n", cmd[0]);
- scsi_remove_request(r);
+ scsi_req_dequeue(&r->req);
+ scsi_req_unref(&r->req);
return 0;
}
scsi_req_fixup(&r->req);
@@ -377,8 +379,10 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
ret = execute_command(s->bs, r, SG_DXFER_NONE, scsi_command_complete);
if (ret == -1) {
scsi_command_complete(r, -EINVAL);
+ scsi_req_unref(&r->req);
return 0;
}
+ scsi_req_unref(&r->req);
return 0;
}
@@ -393,10 +397,13 @@ static int32_t scsi_send_command(SCSIDevice *d, uint32_t
tag,
r->len = r->req.cmd.xfer;
if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
r->len = 0;
- return -r->req.cmd.xfer;
+ len = -r->req.cmd.xfer;
+ } else {
+ len = r->req.cmd.xfer;
}
- return r->req.cmd.xfer;
+ scsi_req_unref(&r->req);
+ return len;
}
static int get_blocksize(BlockDriverState *bdrv)
@@ -469,7 +476,7 @@ static void scsi_generic_purge_requests(SCSIGenericState *s)
if (r->req.aiocb) {
bdrv_aio_cancel(r->req.aiocb);
}
- scsi_remove_request(r);
+ scsi_req_dequeue(&r->req);
}
}
@@ -561,6 +568,7 @@ static SCSIDeviceInfo scsi_generic_info = {
.qdev.reset = scsi_generic_reset,
.init = scsi_generic_initfn,
.destroy = scsi_destroy,
+ .free_req = scsi_free_request,
.send_command = scsi_send_command,
.read_data = scsi_read_data,
.write_data = scsi_write_data,
diff --git a/hw/scsi.h b/hw/scsi.h
index d4ecc9b..a1d0e74 100644
--- a/hw/scsi.h
+++ b/hw/scsi.h
@@ -29,6 +29,7 @@ enum SCSIXferMode {
typedef struct SCSIRequest {
SCSIBus *bus;
SCSIDevice *dev;
+ uint32_t refcount;
uint32_t tag;
uint32_t lun;
uint32_t status;
@@ -65,6 +66,7 @@ struct SCSIDeviceInfo {
DeviceInfo qdev;
scsi_qdev_initfn init;
void (*destroy)(SCSIDevice *s);
+ void (*free_req)(SCSIRequest *req);
int32_t (*send_command)(SCSIDevice *s, uint32_t tag, uint8_t *buf,
int lun);
void (*read_data)(SCSIDevice *s, uint32_t tag);
@@ -103,6 +105,9 @@ int scsi_bus_legacy_handle_cmdline(SCSIBus *bus);
SCSIRequest *scsi_req_alloc(size_t size, SCSIDevice *d, uint32_t tag, uint32_t
lun);
SCSIRequest *scsi_req_find(SCSIDevice *d, uint32_t tag);
void scsi_req_free(SCSIRequest *req);
+void scsi_req_dequeue(SCSIRequest *req);
+SCSIRequest *scsi_req_ref(SCSIRequest *req);
+void scsi_req_unref(SCSIRequest *req);
int scsi_req_parse(SCSIRequest *req, uint8_t *buf);
void scsi_req_print(SCSIRequest *req);
--
1.7.4.4
- [Qemu-devel] [PULL v5 00/25] SCSI subsystem improvements, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 02/25] scsi-generic: Remove bogus double complete, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 04/25] scsi: introduce SCSIBusOps, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 06/25] scsi: reference-count requests,
Paolo Bonzini <=
- [Qemu-devel] [PATCH v5 07/25] lsi: extract lsi_find_by_tag, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 10/25] scsi: introduce scsi_req_abort, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 12/25] scsi: use scsi_req_complete, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 09/25] scsi: commonize purging requests, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 11/25] scsi: introduce scsi_req_cancel, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 13/25] scsi: Update sense code handling, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 14/25] scsi: do not call send_command directly, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 16/25] scsi: introduce scsi_req_continue, Paolo Bonzini, 2011/05/26
- [Qemu-devel] [PATCH v5 17/25] scsi: introduce scsi_req_get_buf, Paolo Bonzini, 2011/05/26