Instead of representing the states "visible in sysfs" and
"has been removed from the target list" by a single state
variable, use two variables to represent this information.
This patch avoids that SCSI device removal can trigger the
following soft lockup:
NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [kworker/1:1:29]
CPU: 1 PID: 29 Comm: kworker/1:1 Tainted: G O 4.4.0-rc5-2.g1e923a3-default #1
Workqueue: fc_wq_4 fc_rport_final_delete [scsi_transport_fc]
Call Trace:
[<c066b0f7>] scsi_remove_target+0x167/0x1c0
[<f8f0a4ed>] fc_rport_final_delete+0x9d/0x1e0 [scsi_transport_fc]
[<c026cb25>] process_one_work+0x155/0x3e0
[<c026cde7>] worker_thread+0x37/0x490
[<c027214b>] kthread+0x9b/0xb0
[<c07e72c1>] ret_from_kernel_thread+0x21/0x40
See also commit bc3f02a795d3 ("scsi_remove_target: fix softlockup
regression on hot remove").
Reported-by: Sebastian Herbszt <herbszt@xxxxxx>
Tested-by: Sebastian Herbszt <herbszt@xxxxxx>
Fixes: commit 40998193560d ("scsi: restart list search after unlock in scsi_remove_target")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
---
drivers/scsi/scsi_scan.c | 31 +++----------------------------
drivers/scsi/scsi_sysfs.c | 7 ++++---
include/scsi/scsi_device.h | 9 ++-------
3 files changed, 9 insertions(+), 38 deletions(-)
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 054923e..c455a88 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -314,7 +314,6 @@ static void scsi_target_destroy(struct scsi_target *starget)
struct Scsi_Host *shost = dev_to_shost(dev->parent);
unsigned long flags;
- starget->state = STARGET_DEL;
transport_destroy_device(dev);
spin_lock_irqsave(shost->host_lock, flags);
if (shost->hostt->target_destroy)
@@ -379,19 +378,15 @@ static void scsi_target_reap_ref_release(struct kref *kref)
struct scsi_target *starget
= container_of(kref, struct scsi_target, reap_ref);
- /*
- * if we get here and the target is still in the CREATED state that
- * means it was allocated but never made visible (because a scan
- * turned up no LUNs), so don't call device_del() on it.
- */
- if (starget->state != STARGET_CREATED) {
+ if (starget->is_visible) {
+ starget->is_visible = false;
transport_remove_device(&starget->dev);
device_del(&starget->dev);
}
scsi_target_destroy(starget);
}
-static void scsi_target_reap_ref_put(struct scsi_target *starget)
+void scsi_target_reap(struct scsi_target *starget)
{
kref_put(&starget->reap_ref, scsi_target_reap_ref_release);
}
@@ -437,7 +432,6 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
starget->can_queue = 0;
INIT_LIST_HEAD(&starget->siblings);
INIT_LIST_HEAD(&starget->devices);
- starget->state = STARGET_CREATED;
starget->scsi_level = SCSI_2;
starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
retry:
@@ -498,25 +492,6 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
}
/**
- * scsi_target_reap - check to see if target is in use and destroy if not
- * @starget: target to be checked
- *
- * This is used after removing a LUN or doing a last put of the target
- * it checks atomically that nothing is using the target and removes
- * it if so.
- */
-void scsi_target_reap(struct scsi_target *starget)
-{
- /*
- * serious problem if this triggers: STARGET_DEL is only set in the if
- * the reap_ref drops to zero, so we're trying to do another final put
- * on an already released kref
- */
- BUG_ON(starget->state == STARGET_DEL);
- scsi_target_reap_ref_put(starget);
-}
-
-/**
* sanitize_inquiry_string - remove non-graphical chars from an INQUIRY result string
* @s: INQUIRY result string to sanitize
* @len: length of the string
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 21930c9..532c062 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1000,7 +1000,7 @@ static int scsi_target_add(struct scsi_target *starget)
{
int error;
- if (starget->state != STARGET_CREATED)
+ if (starget->is_visible)
return 0;
error = device_add(&starget->dev);
@@ -1009,7 +1009,7 @@ static int scsi_target_add(struct scsi_target *starget)
return error;
}
transport_add_device(&starget->dev);
- starget->state = STARGET_RUNNING;
+ starget->is_visible = true;
pm_runtime_set_active(&starget->dev);
pm_runtime_enable(&starget->dev);
@@ -1198,10 +1198,11 @@ void scsi_remove_target(struct device *dev)
restart:
spin_lock_irqsave(shost->host_lock, flags);
list_for_each_entry(starget, &shost->__targets, siblings) {
- if (starget->state == STARGET_DEL)
+ if (starget->reaped)
continue;
if (starget->dev.parent == dev || &starget->dev == dev) {
kref_get(&starget->reap_ref);
+ starget->reaped = true;
spin_unlock_irqrestore(shost->host_lock, flags);
__scsi_remove_target(starget);
scsi_target_reap(starget);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index fe89d7c..f11c794 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -236,12 +236,6 @@ scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
sdev_dbg((scmd)->device, fmt, ##a); \
} while (0)
-enum scsi_target_state {
- STARGET_CREATED = 1,
- STARGET_RUNNING,
- STARGET_DEL,
-};
-
/*
* scsi_target: representation of a scsi target, for now, this is only
* used for single_lun devices. If no one has active IO to the target,
@@ -267,6 +261,8 @@ struct scsi_target {
unsigned int expecting_lun_change:1; /* A device has reported
* a 3F/0E UA, other devices on
* the same target will also. */
+ unsigned int is_visible:1; /* visible in sysfs */
+ unsigned int reaped:1; /* removed from target list */
/* commands actually active on LLD. */
atomic_t target_busy;
atomic_t target_blocked;
@@ -280,7 +276,6 @@ struct scsi_target {
#define SCSI_DEFAULT_TARGET_BLOCKED 3
char scsi_level;
- enum scsi_target_state state;
void *hostdata; /* available to low-level driver */
unsigned long starget_data[0]; /* for the transport */
/* starget_data must be the last element!!!! */
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
