[PATCH v6 05/10] scsi: scsi_debug: Return failed value if the error is injected

From: Wenchao Hao
Date: Tue Oct 10 2023 - 05:21:54 EST


If a fail queuecommand error is injected, return the failed value defined
in the rule from queuecommand.

Make queuecommand return format:
+--------+------+-------------------------------------------------------+
| Column | Type | Description |
+--------+------+-------------------------------------------------------+
| 1 | u8 | Error type, fixed to 0x1 |
+--------+------+-------------------------------------------------------+
| 2 | s32 | Error count |
| | | 0: this rule will be ignored |
| | | positive: the rule will always take effect |
| | | negative: the rule takes effect n times where -n is |
| | | the value given. Ignored after n times |
+--------+------+-------------------------------------------------------+
| 3 | x8 | SCSI command opcode, 0xff for all commands |
+--------+------+-------------------------------------------------------+
| 4 | x32 | The queuecommand() return value we want |
+--------+------+-------------------------------------------------------+

Examples:
error=/sys/kernel/debug/scsi_debug/0:0:0:1/error
echo "1 1 0x12 0x1055" > ${error}
will make each INQUIRY command sent to that device return
0x1055 (SCSI_MLQUEUE_HOST_BUSY).

Acked-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
Signed-off-by: Wenchao Hao <haowenchao2@xxxxxxxxxx>
---
drivers/scsi/scsi_debug.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 9081c9d22882..efdd63dd6d25 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -7769,6 +7769,34 @@ 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;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(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++;
+
+ rcu_read_unlock();
+ return ret;
+ }
+ }
+ rcu_read_unlock();
+
+ return 0;
+}
+
static int scsi_debug_queuecommand(struct Scsi_Host *shost,
struct scsi_cmnd *scp)
{
@@ -7788,6 +7816,7 @@ 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) {
@@ -7833,6 +7862,13 @@ 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);

--
2.32.0