Commit 3e16e83a authored by Don Brace's avatar Don Brace Committed by Martin K. Petersen
Browse files

scsi: hpsa: correct race condition in offload enabled 

Correct race condition where ioaccel is re-enabled before the raid_map is
updated. For RAID_1, RAID_1ADM, and RAID 5/6 there is a BUG_ON called which
is bad.

 - Change event thread to disable ioaccel only. Send all requests down the
   RAID path instead.

 - Have rescan thread handle offload_enable.

 - Since there is only one rescan allowed at a time, turning
   offload_enabled on/off should not be racy. Each handler queues up a
   rescan if one is already in progress.

  - For timing diagram, offload_enabled is initially off due to a change
    (transformation: splitmirror/remirror), ...

  otbe = offload_to_be_enabled
  oe   = offload_enabled

  Time Event         Rescan              Completion     Request
       Worker        Worker              Thread         Thread
  ---- ------        ------              ----------     -------
   T0   |             |                       + UA      |
   T1   |             + rescan started        | 0x3f    |
   T2   + Event       |                       | 0x0e    |
   T3   + Ack msg     |                       |         |
   T4   |             + if (!dev[i]->oe &&    |         |
   T5   |             |     dev[i]->otbe)     |         |
   T6   |             |      get_raid_map     |         |
   T7   + otbe = 1    |                       |         |
   T8   |             |                       |         |
   T9   |             + oe = otbe             |         |
   T10  |             |                       |         + ioaccel request
   T11                                                  * BUG_ON

  T0 - I/O completion with UA 0x3f 0x0e sets rescan flag.
  T1 - rescan worker thread starts a rescan.
  T2 - event comes in
  T3 - event thread starts and issues "Acknowledge" message
  ...
  T6 - rescan thread has bypassed code to reload new raid map.
  ...
  T7 - event thread runs and sets offload_to_be_enabled
  ...
  T9 - rescan thread turns on offload_enabled.
  T10- request comes in and goes down ioaccel path.
  T11- BUG_ON.

 - After the patch is applied, ioaccel_enabled can only be re-enabled in
   the re-scan thread.

Link: https://lore.kernel.org/r/158472877894.14200.7077843399036368335.stgit@brunhilda


Reviewed-by: default avatarScott Teel <scott.teel@microsemi.com>
Reviewed-by: default avatarMatt Perricone <matt.perricone@microsemi.com>
Reviewed-by: default avatarScott Benesh <scott.benesh@microsemi.com>
Signed-off-by: default avatarDon Brace <don.brace@microsemi.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent fd6282af

drivers/scsi/hpsa.c

+57 −23
Original line number Diff line number Diff line
@@ -504,6 +504,12 @@ static ssize_t host_store_rescan(struct device *dev, 
	return count;

}



static void hpsa_turn_off_ioaccel_for_device(struct hpsa_scsi_dev_t *device)

{

	device->offload_enabled = 0;

	device->offload_to_be_enabled = 0;

}



static ssize_t host_show_firmware_revision(struct device *dev,

	     struct device_attribute *attr, char *buf)

{
@@ -1738,8 +1744,7 @@ static void hpsa_figure_phys_disk_ptrs(struct ctlr_info *h, 
				__func__,

				h->scsi_host->host_no, logical_drive->bus,

				logical_drive->target, logical_drive->lun);

			logical_drive->offload_enabled = 0;

			logical_drive->offload_to_be_enabled = 0;

			hpsa_turn_off_ioaccel_for_device(logical_drive);

			logical_drive->queue_depth = 8;

		}

	}
@@ -2499,8 +2504,7 @@ static void process_ioaccel2_completion(struct ctlr_info *h, 
			IOACCEL2_SERV_RESPONSE_FAILURE) {

		if (c2->error_data.status ==

			IOACCEL2_STATUS_SR_IOACCEL_DISABLED) {

			dev->offload_enabled = 0;

			dev->offload_to_be_enabled = 0;

			hpsa_turn_off_ioaccel_for_device(dev);

		}



		if (dev->in_reset) {
@@ -3670,10 +3674,17 @@ static void hpsa_get_ioaccel_status(struct ctlr_info *h, 
	this_device->offload_config =

		!!(ioaccel_status & OFFLOAD_CONFIGURED_BIT);

	if (this_device->offload_config) {

		this_device->offload_to_be_enabled =

		bool offload_enabled =

			!!(ioaccel_status & OFFLOAD_ENABLED_BIT);

		if (hpsa_get_raid_map(h, scsi3addr, this_device))

			this_device->offload_to_be_enabled = 0;

		/*

		 * Check to see if offload can be enabled.

		 */

		if (offload_enabled) {

			rc = hpsa_get_raid_map(h, scsi3addr, this_device);

			if (rc) /* could not load raid_map */

				goto out;

			this_device->offload_to_be_enabled = 1;

		}

	}



out:
@@ -3996,8 +4007,7 @@ static int hpsa_update_device_info(struct ctlr_info *h, 
	} else {

		this_device->raid_level = RAID_UNKNOWN;

		this_device->offload_config = 0;

		this_device->offload_enabled = 0;

		this_device->offload_to_be_enabled = 0;

		hpsa_turn_off_ioaccel_for_device(this_device);

		this_device->hba_ioaccel_enabled = 0;

		this_device->volume_offline = 0;

		this_device->queue_depth = h->nr_cmds;
@@ -5230,8 +5240,12 @@ static int hpsa_scsi_ioaccel_raid_map(struct ctlr_info *h, 
		/* Handles load balance across RAID 1 members.

		 * (2-drive R1 and R10 with even # of drives.)

		 * Appropriate for SSDs, not optimal for HDDs

		 * Ensure we have the correct raid_map.

		 */

		BUG_ON(le16_to_cpu(map->layout_map_count) != 2);

		if (le16_to_cpu(map->layout_map_count) != 2) {

			hpsa_turn_off_ioaccel_for_device(dev);

			return IO_ACCEL_INELIGIBLE;

		}

		if (dev->offload_to_mirror)

			map_index += le16_to_cpu(map->data_disks_per_row);

		dev->offload_to_mirror = !dev->offload_to_mirror;
@@ -5239,8 +5253,12 @@ static int hpsa_scsi_ioaccel_raid_map(struct ctlr_info *h, 
	case HPSA_RAID_ADM:

		/* Handles N-way mirrors  (R1-ADM)

		 * and R10 with # of drives divisible by 3.)

		 * Ensure we have the correct raid_map.

		 */

		BUG_ON(le16_to_cpu(map->layout_map_count) != 3);

		if (le16_to_cpu(map->layout_map_count) != 3) {

			hpsa_turn_off_ioaccel_for_device(dev);

			return IO_ACCEL_INELIGIBLE;

		}



		offload_to_mirror = dev->offload_to_mirror;

		raid_map_helper(map, offload_to_mirror,
@@ -5265,7 +5283,10 @@ static int hpsa_scsi_ioaccel_raid_map(struct ctlr_info *h, 
		r5or6_blocks_per_row =

			le16_to_cpu(map->strip_size) *

			le16_to_cpu(map->data_disks_per_row);

		BUG_ON(r5or6_blocks_per_row == 0);

		if (r5or6_blocks_per_row == 0) {

			hpsa_turn_off_ioaccel_for_device(dev);

			return IO_ACCEL_INELIGIBLE;

		}

		stripesize = r5or6_blocks_per_row *

			le16_to_cpu(map->layout_map_count);

#if BITS_PER_LONG == 32
@@ -8285,7 +8306,7 @@ static int detect_controller_lockup(struct ctlr_info *h) 
 *

 * Called from monitor controller worker (hpsa_event_monitor_worker)

 *

 * A Volume (or Volumes that comprise an Array set may be undergoing a

 * A Volume (or Volumes that comprise an Array set) may be undergoing a

 * transformation, so we will be turning off ioaccel for all volumes that

 * make up the Array.

 */
@@ -8308,6 +8329,9 @@ static void hpsa_set_ioaccel_status(struct ctlr_info *h) 
	 * Run through current device list used during I/O requests.

	 */

	for (i = 0; i < h->ndevices; i++) {

		int offload_to_be_enabled = 0;

		int offload_config = 0;



		device = h->dev[i];



		if (!device)
@@ -8325,25 +8349,35 @@ static void hpsa_set_ioaccel_status(struct ctlr_info *h) 
			continue;



		ioaccel_status = buf[IOACCEL_STATUS_BYTE];

		device->offload_config =



		/*

		 * Check if offload is still configured on

		 */

		offload_config =

				!!(ioaccel_status & OFFLOAD_CONFIGURED_BIT);

		if (device->offload_config)

			device->offload_to_be_enabled =

		/*

		 * If offload is configured on, check to see if ioaccel

		 * needs to be enabled.

		 */

		if (offload_config)

			offload_to_be_enabled =

				!!(ioaccel_status & OFFLOAD_ENABLED_BIT);



		/*

		 * If ioaccel is to be re-enabled, re-enable later during the

		 * scan operation so the driver can get a fresh raidmap

		 * before turning ioaccel back on.

		 */

		if (offload_to_be_enabled)

			continue;



		/*

		 * Immediately turn off ioaccel for any volume the

		 * controller tells us to. Some of the reasons could be:

		 *    transformation - change to the LVs of an Array.

		 *    degraded volume - component failure

		 *

		 * If ioaccel is to be re-enabled, re-enable later during the

		 * scan operation so the driver can get a fresh raidmap

		 * before turning ioaccel back on.

		 *

		 */

		if (!device->offload_to_be_enabled)

			device->offload_enabled = 0;

		hpsa_turn_off_ioaccel_for_device(device);

	}



	kfree(buf);

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