scsi: sd: Revert "Rework asynchronous resume support"

Although commit 88f1669019bd ("scsi: sd: Rework asynchronous resume support")
eliminates a delay for some ATA disks after resume, it causes resume of ATA
disks to fail on other setups. See also:

 * "Resume process hangs for 5-6 seconds starting sometime in 5.16"
   (https://bugzilla.kernel.org/show_bug.cgi?id=215880).

 * Geert's regression report
   (https://lore.kernel.org/linux-scsi/alpine.DEB.2.22.394.2207191125130.1006766@ramsan.of.borg/).

This is what I understand about this issue:

 * During resume, ata_port_pm_resume() starts the SCSI error handler.  This
   changes the SCSI host state into SHOST_RECOVERY and causes
   scsi_queue_rq() to return BLK_STS_RESOURCE.

 * sd_resume() calls sd_start_stop_device() for ATA devices. That function
   in turn calls sd_submit_start() which tries to submit a START STOP UNIT
   command. That command can only be submitted after the SCSI error handler
   has changed the SCSI host state back to SHOST_RUNNING.

 * The SCSI error handler runs on its own thread and calls
   schedule_work(&(ap->scsi_rescan_task)). That causes
   ata_scsi_dev_rescan() to be called from the context of a kernel
   workqueue. That call hangs in blk_mq_get_tag(). I'm not sure why - maybe
   because all available tags have been allocated by sd_submit_start()
   calls (this is a guess).

Link: https://lore.kernel.org/r/20220816172638.538734-1-bvanassche@acm.org
Fixes: 88f1669019bd ("scsi: sd: Rework asynchronous resume support")
Cc: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: gzhqyz@gmail.com
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: gzhqyz@gmail.com
Reported-and-tested-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: John Garry <john.garry@huawei.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 8f79fa6318fec25bd7a50e5e9c3b19addc3361cd..eb76ba0550216d7d55d998e4609ed7ea5d4bdb9a 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -103,7 +103,6 @@ static void sd_config_discard(struct scsi_disk *, unsigned int);
 static void sd_config_write_same(struct scsi_disk *);
 static int  sd_revalidate_disk(struct gendisk *);
 static void sd_unlock_native_capacity(struct gendisk *disk);
-static void sd_start_done_work(struct work_struct *work);
 static int  sd_probe(struct device *);
 static int  sd_remove(struct device *);
 static void sd_shutdown(struct device *);
@@ -3471,7 +3470,6 @@ static int sd_probe(struct device *dev)
        sdkp->max_retries = SD_MAX_RETRIES;
        atomic_set(&sdkp->openers, 0);
        atomic_set(&sdkp->device->ioerr_cnt, 0);
-       INIT_WORK(&sdkp->start_done_work, sd_start_done_work);
 
        if (!sdp->request_queue->rq_timeout) {
                if (sdp->type != TYPE_MOD)
@@ -3594,69 +3592,12 @@ static void scsi_disk_release(struct device *dev)
        kfree(sdkp);
 }
 
-/* Process sense data after a START command finished. */
-static void sd_start_done_work(struct work_struct *work)
-{
-       struct scsi_disk *sdkp = container_of(work, typeof(*sdkp),
-                                             start_done_work);
-       struct scsi_sense_hdr sshdr;
-       int res = sdkp->start_result;
-
-       if (res == 0)
-               return;
-
-       sd_print_result(sdkp, "Start/Stop Unit failed", res);
-
-       if (res < 0)
-               return;
-
-       if (scsi_normalize_sense(sdkp->start_sense_buffer,
-                                sdkp->start_sense_len, &sshdr))
-               sd_print_sense_hdr(sdkp, &sshdr);
-}
-
-/* A START command finished. May be called from interrupt context. */
-static void sd_start_done(struct request *req, blk_status_t status)
-{
-       const struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
-       struct scsi_disk *sdkp = scsi_disk(req->q->disk);
-
-       sdkp->start_result = scmd->result;
-       WARN_ON_ONCE(scmd->sense_len > SCSI_SENSE_BUFFERSIZE);
-       sdkp->start_sense_len = scmd->sense_len;
-       memcpy(sdkp->start_sense_buffer, scmd->sense_buffer,
-              ARRAY_SIZE(sdkp->start_sense_buffer));
-       WARN_ON_ONCE(!schedule_work(&sdkp->start_done_work));
-}
-
-/* Submit a START command asynchronously. */
-static int sd_submit_start(struct scsi_disk *sdkp, u8 cmd[], u8 cmd_len)
-{
-       struct scsi_device *sdev = sdkp->device;
-       struct request_queue *q = sdev->request_queue;
-       struct request *req;
-       struct scsi_cmnd *scmd;
-
-       req = scsi_alloc_request(q, REQ_OP_DRV_IN, BLK_MQ_REQ_PM);
-       if (IS_ERR(req))
-               return PTR_ERR(req);
-
-       scmd = blk_mq_rq_to_pdu(req);
-       scmd->cmd_len = cmd_len;
-       memcpy(scmd->cmnd, cmd, cmd_len);
-       scmd->allowed = sdkp->max_retries;
-       req->timeout = SD_TIMEOUT;
-       req->rq_flags |= RQF_PM | RQF_QUIET;
-       req->end_io = sd_start_done;
-       blk_execute_rq_nowait(req, /*at_head=*/true);
-
-       return 0;
-}
-
 static int sd_start_stop_device(struct scsi_disk *sdkp, int start)
 {
        unsigned char cmd[6] = { START_STOP };  /* START_VALID */
+       struct scsi_sense_hdr sshdr;
        struct scsi_device *sdp = sdkp->device;
+       int res;
 
        if (start)
                cmd[4] |= 1;    /* START */
@@ -3667,10 +3608,23 @@ static int sd_start_stop_device(struct scsi_disk *sdkp, int start)
        if (!scsi_device_online(sdp))
                return -ENODEV;
 
-       /* Wait until processing of sense data has finished. */
-       flush_work(&sdkp->start_done_work);
+       res = scsi_execute(sdp, cmd, DMA_NONE, NULL, 0, NULL, &sshdr,
+                       SD_TIMEOUT, sdkp->max_retries, 0, RQF_PM, NULL);
+       if (res) {
+               sd_print_result(sdkp, "Start/Stop Unit failed", res);
+               if (res > 0 && scsi_sense_valid(&sshdr)) {
+                       sd_print_sense_hdr(sdkp, &sshdr);
+                       /* 0x3a is medium not present */
+                       if (sshdr.asc == 0x3a)
+                               res = 0;
+               }
+       }
 
-       return sd_submit_start(sdkp, cmd, sizeof(cmd));
+       /* SCSI error codes must not go to the generic layer */
+       if (res)
+               return -EIO;
+
+       return 0;
 }
 
 /*
@@ -3697,8 +3651,6 @@ static void sd_shutdown(struct device *dev)
                sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
                sd_start_stop_device(sdkp, 0);
        }
-
-       flush_work(&sdkp->start_done_work);
 }
 
 static int sd_suspend_common(struct device *dev, bool ignore_stop_errors)

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index b89187761d61f33af307bc0a91b656b1df4373bc..5eea762f84d188e15b516b05f0f98ba3892209a5 100644 (file)
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -150,11 +150,6 @@ struct scsi_disk {
        unsigned        urswrz : 1;
        unsigned        security : 1;
        unsigned        ignore_medium_access_errors : 1;
-
-       int             start_result;
-       u32             start_sense_len;
-       u8              start_sense_buffer[SCSI_SENSE_BUFFERSIZE];
-       struct work_struct start_done_work;
 };
 #define to_scsi_disk(obj) container_of(obj, struct scsi_disk, disk_dev)