scsi: scsi_debug: Fix request sense

The SCSI REQUEST SENSE command emulation was found to be broken.  It is a
quite complex command so try and make it do a subset of what it should
do. Remove the attempt to mimic SCSI-1 REQUEST SENSE (i.e. return the sense
data for the previous failed command). Add some reporting of "pollable"
sense data [see spc6r02: 5.12.2]. Keep the IEC mode page MRIE=6 TEST=1
predictive failure reporting.

Link: https://lore.kernel.org/r/20200723194819.545573-1-dgilbert@interlog.com
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index dff599b..f227359 100644 (file)
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -1712,68 +1712,62 @@ static int resp_inquiry(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
        return ret;
 }
 
+/* See resp_iec_m_pg() for how this data is manipulated */
 static unsigned char iec_m_pg[] = {0x1c, 0xa, 0x08, 0, 0, 0, 0, 0,
                                   0, 0, 0x0, 0x0};
 
 static int resp_requests(struct scsi_cmnd *scp,
                         struct sdebug_dev_info *devip)
 {
-       unsigned char *sbuff;
        unsigned char *cmd = scp->cmnd;
-       unsigned char arr[SCSI_SENSE_BUFFERSIZE];
-       bool dsense;
+       unsigned char arr[SCSI_SENSE_BUFFERSIZE];       /* assume >= 18 bytes */
+       bool dsense = !!(cmd[1] & 1);
+       int alloc_len = cmd[4];
        int len = 18;
+       int stopped_state = atomic_read(&devip->stopped);
 
        memset(arr, 0, sizeof(arr));
-       dsense = !!(cmd[1] & 1);
-       sbuff = scp->sense_buffer;
-       if ((iec_m_pg[2] & 0x4) && (6 == (iec_m_pg[3] & 0xf))) {
+       if (stopped_state > 0) {        /* some "pollable" data [spc6r02: 5.12.2] */
+               if (dsense) {
+                       arr[0] = 0x72;
+                       arr[1] = NOT_READY;
+                       arr[2] = LOGICAL_UNIT_NOT_READY;
+                       arr[3] = (stopped_state == 2) ? 0x1 : 0x2;
+                       len = 8;
+               } else {
+                       arr[0] = 0x70;
+                       arr[2] = NOT_READY;             /* NO_SENSE in sense_key */
+                       arr[7] = 0xa;                   /* 18 byte sense buffer */
+                       arr[12] = LOGICAL_UNIT_NOT_READY;
+                       arr[13] = (stopped_state == 2) ? 0x1 : 0x2;
+               }
+       } else if ((iec_m_pg[2] & 0x4) && (6 == (iec_m_pg[3] & 0xf))) {
+               /* Information exceptions control mode page: TEST=1, MRIE=6 */
                if (dsense) {
                        arr[0] = 0x72;
                        arr[1] = 0x0;           /* NO_SENSE in sense_key */
                        arr[2] = THRESHOLD_EXCEEDED;
-                       arr[3] = 0xff;          /* TEST set and MRIE==6 */
+                       arr[3] = 0xff;          /* Failure prediction(false) */
                        len = 8;
                } else {
                        arr[0] = 0x70;
                        arr[2] = 0x0;           /* NO_SENSE in sense_key */
                        arr[7] = 0xa;           /* 18 byte sense buffer */
                        arr[12] = THRESHOLD_EXCEEDED;
-                       arr[13] = 0xff;         /* TEST set and MRIE==6 */
+                       arr[13] = 0xff;         /* Failure prediction(false) */
                }
-       } else {
-               memcpy(arr, sbuff, SCSI_SENSE_BUFFERSIZE);
-               if (arr[0] >= 0x70 && dsense == sdebug_dsense)
-                       ;       /* have sense and formats match */
-               else if (arr[0] <= 0x70) {
-                       if (dsense) {
-                               memset(arr, 0, 8);
-                               arr[0] = 0x72;
-                               len = 8;
-                       } else {
-                               memset(arr, 0, 18);
-                               arr[0] = 0x70;
-                               arr[7] = 0xa;
-                       }
-               } else if (dsense) {
-                       memset(arr, 0, 8);
-                       arr[0] = 0x72;
-                       arr[1] = sbuff[2];     /* sense key */
-                       arr[2] = sbuff[12];    /* asc */
-                       arr[3] = sbuff[13];    /* ascq */
+       } else {        /* nothing to report */
+               if (dsense) {
                        len = 8;
+                       memset(arr, 0, len);
+                       arr[0] = 0x72;
                } else {
-                       memset(arr, 0, 18);
+                       memset(arr, 0, len);
                        arr[0] = 0x70;
-                       arr[2] = sbuff[1];
                        arr[7] = 0xa;
-                       arr[12] = sbuff[1];
-                       arr[13] = sbuff[3];
                }
-
        }
-       mk_sense_buffer(scp, 0, NO_ADDITIONAL_SENSE, 0);
-       return fill_from_dev_buffer(scp, arr, len);
+       return fill_from_dev_buffer(scp, arr, min_t(int, len, alloc_len));
 }
 
 static int resp_start_stop(struct scsi_cmnd *scp,