On Mon, 2008-08-11 at 13:03 -0500, Brian King wrote:
> The following patch fixes an oops which was observed during device scanning.
> If LUN 0 does not exist for a valid target, but non-zero LUNs do exist, a struct
> scsi_device exists only when probing the target and is deleted by the scanning
> code, by checking to see if the device's state is SDEV_CREATED. If, while scanning,
> the rport is deleted, such that target is placed into the blocked state, and
> then later the rport is added again, the LUN 0 sdev finds its way into the SDEV_RUNNING
> state. This causes the scanning code to NOT delete the sdev when scanning is complete.
> Later on, if the target is deleted, we will oops when we try to free up everything
> that gets allocated in scsi_sysfs_add_sdev, since it was never added. This patch
> fixes this issue, by adding a added_to_sysfs flag to struct scsi_device, which is
> then checked to determine what to do, both in the device probe exit code and the
> device remove code.
What this seems to be exposing is a bug in the state model around the
blocked state.
The transition:
CREATED -> BLOCK -> RUNNING
shouldn't be legal. My initial reaction is just to forbid the CREATED
-> BLOCK transition, but it looks like the fc transport code never
checks return values from scsi_target_block() (sigh!)
So an alternate fix should be to correct the state model rather than try
and work around the deficiencies with additional flags.
It looks like, to allow the CREATED -> BLOCK -> CREATED transition we
need an extra state (CREATED_BLOCK) and we forbid the CREATED -> BLOCK
in favour of it.
The model also now allows an online transition to do CREATED_BLOCK ->
BLOCK
This is a rough code of that, does it work for you?
James
---
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ff5d56b..42b33a3 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1250,6 +1250,7 @@ int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
break;
case SDEV_QUIESCE:
case SDEV_BLOCK:
+ case SDEV_CREATED_BLOCK:
/*
* If the devices is blocked we defer normal commands.
*/
@@ -2063,10 +2064,13 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
switch (state) {
case SDEV_CREATED:
- /* There are no legal states that come back to
- * created. This is the manually initialised start
- * state */
- goto illegal;
+ switch (oldstate) {
+ case SDEV_CREATED_BLOCK:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
case SDEV_RUNNING:
switch (oldstate) {
@@ -2104,8 +2108,17 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
case SDEV_BLOCK:
switch (oldstate) {
- case SDEV_CREATED:
case SDEV_RUNNING:
+ case SDEV_CREATED_BLOCK:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ case SDEV_CREATED_BLOCK:
+ switch (oldstate) {
+ case SDEV_CREATED:
break;
default:
goto illegal;
@@ -2393,8 +2406,12 @@ scsi_internal_device_block(struct scsi_device *sdev)
int err = 0;
err = scsi_device_set_state(sdev, SDEV_BLOCK);
- if (err)
- return err;
+ if (err) {
+ err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
+
+ if (err)
+ return err;
+ }
/*
* The device has transitioned to SDEV_BLOCK. Stop the
@@ -2437,8 +2454,12 @@ scsi_internal_device_unblock(struct scsi_device *sdev)
* and goose the device queue if successful.
*/
err = scsi_device_set_state(sdev, SDEV_RUNNING);
- if (err)
- return err;
+ if (err) {
+ err = scsi_device_set_state(sdev, SDEV_CREATED);
+
+ if (err)
+ return err;
+ }
spin_lock_irqsave(q->queue_lock, flags);
blk_start_queue(q);
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 84b4879..c6791a7 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -730,6 +730,8 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
int *bflags, int async)
{
+ int ret;
+
/*
* XXX do not save the inquiry, since it can change underneath us,
* save just vendor/model/rev.
@@ -885,7 +887,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
/* set the device running here so that slave configure
* may do I/O */
- scsi_device_set_state(sdev, SDEV_RUNNING);
+ ret = scsi_device_set_state(sdev, SDEV_RUNNING);
+ if (ret) {
+ ret = scsi_device_set_state(sdev, SDEV_BLOCK);
+
+ if (ret) {
+ sdev_printk(KERN_ERR, sdev,
+ "in wrong state %s to complete scan\n",
+ scsi_device_state_name(sdev->sdev_state));
+ return SCSI_SCAN_NO_RESPONSE;
+ }
+ }
if (*bflags & BLIST_MS_192_BYTES_FOR_3F)
sdev->use_192_bytes_for_3f = 1;
@@ -899,7 +911,7 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
transport_configure_device(&sdev->sdev_gendev);
if (sdev->host->hostt->slave_configure) {
- int ret = sdev->host->hostt->slave_configure(sdev);
+ ret = sdev->host->hostt->slave_configure(sdev);
if (ret) {
/*
* if LLDD reports slave not present, don't clutter
@@ -994,7 +1006,8 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
*/
sdev = scsi_device_lookup_by_target(starget, lun);
if (sdev) {
- if (rescan || sdev->sdev_state != SDEV_CREATED) {
+ if (rescan || (sdev->sdev_state != SDEV_CREATED &&
+ sdev->sdev_state != SDEV_CREATED_BLOCK)) {
SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
"scsi scan: device exists on %s\n",
sdev->sdev_gendev.bus_id));
@@ -1466,7 +1479,8 @@ static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
kfree(lun_data);
out:
scsi_device_put(sdev);
- if (sdev->sdev_state == SDEV_CREATED)
+ if (sdev->sdev_state == SDEV_CREATED ||
+ sdev->sdev_state == SDEV_CREATED_BLOCK)
/*
* the sdev we used didn't appear in the report luns scan
*/
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index ab3c718..09d311d 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -34,6 +34,7 @@ static const struct {
{ SDEV_QUIESCE, "quiesce" },
{ SDEV_OFFLINE, "offline" },
{ SDEV_BLOCK, "blocked" },
+ { SDEV_CREATED_BLOCK, "created-blocked" },
};
const char *scsi_device_state_name(enum scsi_device_state state)
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 80b2e93..ad3d42d 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -42,9 +42,11 @@ enum scsi_device_state {
* originate in the mid-layer) */
SDEV_OFFLINE, /* Device offlined (by error handling or
* user request */
- SDEV_BLOCK, /* Device blocked by scsi lld. No scsi
- * commands from user or midlayer should be issued
- * to the scsi lld. */
+ SDEV_BLOCK, /* Device blocked by scsi lld. No
+ * scsi commands from user or midlayer
+ * should be issued to the scsi
+ * lld. */
+ SDEV_CREATED_BLOCK, /* same as above but for created devices */
};
enum scsi_device_event {
--
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