[RFC PATCH 4/5] scsi:scsi_debug: Return failed value for specific command's queuecommand

[Wenchao Hao <haowenchao@huawei.com>]

If a fail queuecommand error is injected for specific scsi command, just
return the failed value rejected in queuecommand.

We can make any scsi command's queuecommand return the value we desired,
for example make it return SCSI_MLQUEUE_HOST_BUSY.

For example the following command would make all inquiry(0x12) command's
queuecommand return 0x1055:

  echo "1 1 0x12 0x1055" >/sys/block/sdb/device/error_inject/error

Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
---
 drivers/scsi/scsi_debug.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 761e1e3bcb9a..217a9e892391 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -7808,6 +7808,30 @@ static int sdebug_timeout_cmd(struct scsi_cmnd *cmnd)
 	return 0;
 }
 
+static int sdebug_fail_queue_cmd(struct scsi_cmnd *cmnd)
+{
+	struct scsi_device *sdp = cmnd->device;
+	struct sdebug_dev_info *devip = (struct sdebug_dev_info *)sdp->hostdata;
+	struct sdebug_err_inject *err;
+	unsigned char *cmd = cmnd->cmnd;
+	int ret = 0;
+
+	if (devip == NULL)
+		return 0;
+
+	list_for_each_entry(err, &devip->inject_err_list, list) {
+		if (err->type == ERR_FAIL_QUEUE_CMD &&
+		    (err->cmd == cmd[0] || err->cmd == 0xff)) {
+			ret = err->cnt ? err->queuecmd_ret : 0;
+			if (err->cnt < 0)
+				err->cnt++;
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 static int scsi_debug_queuecommand(struct Scsi_Host *shost,
 				   struct scsi_cmnd *scp)
 {
@@ -7827,6 +7851,7 @@ static int scsi_debug_queuecommand(struct Scsi_Host *shost,
 	u8 opcode = cmd[0];
 	bool has_wlun_rl;
 	bool inject_now;
+	int ret = 0;
 
 	scsi_set_resid(scp, 0);
 	if (sdebug_statistics) {
@@ -7872,6 +7897,13 @@ static int scsi_debug_queuecommand(struct Scsi_Host *shost,
 		return 0;
 	}
 
+	ret = sdebug_fail_queue_cmd(scp);
+	if (ret) {
+		scmd_printk(KERN_INFO, scp, "fail queue command 0x%x with 0x%x\n",
+				opcode, ret);
+		return ret;
+	}
+
 	if (unlikely(inject_now && !atomic_read(&sdeb_inject_pending)))
 		atomic_set(&sdeb_inject_pending, 1);
 
-- 
2.35.3