diff options
| -rw-r--r-- | drivers/scsi/scsi_scan.c | 99 | ||||
| -rw-r--r-- | drivers/scsi/scsi_sysfs.c | 20 | ||||
| -rw-r--r-- | include/scsi/scsi_device.h | 3 |
3 files changed, 75 insertions, 47 deletions
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 307a81137607..5fad646ee6e5 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -371,6 +371,31 @@ static struct scsi_target *__scsi_find_target(struct device *parent, } /** + * scsi_target_reap_ref_release - remove target from visibility + * @kref: the reap_ref in the target being released + * + * Called on last put of reap_ref, which is the indication that no device + * under this target is visible anymore, so render the target invisible in + * sysfs. Note: we have to be in user context here because the target reaps + * should be done in places where the scsi device visibility is being removed. + */ +static void scsi_target_reap_ref_release(struct kref *kref) +{ + struct scsi_target *starget + = container_of(kref, struct scsi_target, reap_ref); + + transport_remove_device(&starget->dev); + device_del(&starget->dev); + starget->state = STARGET_DEL; + scsi_target_destroy(starget); +} + +static void scsi_target_reap_ref_put(struct scsi_target *starget) +{ + kref_put(&starget->reap_ref, scsi_target_reap_ref_release); +} + +/** * scsi_alloc_target - allocate a new or find an existing target * @parent: parent of the target (need not be a scsi host) * @channel: target channel number (zero if no channels) @@ -392,7 +417,7 @@ static struct scsi_target *scsi_alloc_target(struct device *parent, + shost->transportt->target_size; struct scsi_target *starget; struct scsi_target *found_target; - int error; + int error, ref_got; starget = kzalloc(size, GFP_KERNEL); if (!starget) { @@ -401,7 +426,7 @@ static struct scsi_target *scsi_alloc_target(struct device *parent, } dev = &starget->dev; device_initialize(dev); - starget->reap_ref = 1; + kref_init(&starget->reap_ref); dev->parent = get_device(parent); dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id); dev->bus = &scsi_bus_type; @@ -441,29 +466,36 @@ static struct scsi_target *scsi_alloc_target(struct device *parent, return starget; found: - found_target->reap_ref++; + /* + * release routine already fired if kref is zero, so if we can still + * take the reference, the target must be alive. If we can't, it must + * be dying and we need to wait for a new target + */ + ref_got = kref_get_unless_zero(&found_target->reap_ref); + spin_unlock_irqrestore(shost->host_lock, flags); - if (found_target->state != STARGET_DEL) { + if (ref_got) { put_device(dev); return found_target; } - /* Unfortunately, we found a dying target; need to - * wait until it's dead before we can get a new one */ + /* + * Unfortunately, we found a dying target; need to wait until it's + * dead before we can get a new one. There is an anomaly here. We + * *should* call scsi_target_reap() to balance the kref_get() of the + * reap_ref above. However, since the target being released, it's + * already invisible and the reap_ref is irrelevant. If we call + * scsi_target_reap() we might spuriously do another device_del() on + * an already invisible target. + */ put_device(&found_target->dev); - flush_scheduled_work(); + /* + * length of time is irrelevant here, we just want to yield the CPU + * for a tick to avoid busy waiting for the target to die. + */ + msleep(1); goto retry; } -static void scsi_target_reap_usercontext(struct work_struct *work) -{ - struct scsi_target *starget = - container_of(work, struct scsi_target, ew.work); - - transport_remove_device(&starget->dev); - device_del(&starget->dev); - scsi_target_destroy(starget); -} - /** * scsi_target_reap - check to see if target is in use and destroy if not * @starget: target to be checked @@ -474,28 +506,11 @@ static void scsi_target_reap_usercontext(struct work_struct *work) */ void scsi_target_reap(struct scsi_target *starget) { - struct Scsi_Host *shost = dev_to_shost(starget->dev.parent); - unsigned long flags; - enum scsi_target_state state; - int empty = 0; - - spin_lock_irqsave(shost->host_lock, flags); - state = starget->state; - if (--starget->reap_ref == 0 && list_empty(&starget->devices)) { - empty = 1; - starget->state = STARGET_DEL; - } - spin_unlock_irqrestore(shost->host_lock, flags); - - if (!empty) - return; - - BUG_ON(state == STARGET_DEL); - if (state == STARGET_CREATED) + BUG_ON(starget->state == STARGET_DEL); + if (starget->state == STARGET_CREATED) scsi_target_destroy(starget); else - execute_in_process_context(scsi_target_reap_usercontext, - &starget->ew); + scsi_target_reap_ref_put(starget); } /** @@ -1532,6 +1547,10 @@ struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel, } mutex_unlock(&shost->scan_mutex); scsi_autopm_put_target(starget); + /* + * paired with scsi_alloc_target(). Target will be destroyed unless + * scsi_probe_and_add_lun made an underlying device visible + */ scsi_target_reap(starget); put_device(&starget->dev); @@ -1612,8 +1631,10 @@ static void __scsi_scan_target(struct device *parent, unsigned int channel, out_reap: scsi_autopm_put_target(starget); - /* now determine if the target has any children at all - * and if not, nuke it */ + /* + * paired with scsi_alloc_target(): determine if the target has + * any children at all and if not, nuke it + */ scsi_target_reap(starget); put_device(&starget->dev); diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 9117d0bf408e..665acbf83693 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -383,17 +383,14 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) { struct scsi_device *sdev; struct device *parent; - struct scsi_target *starget; struct list_head *this, *tmp; unsigned long flags; sdev = container_of(work, struct scsi_device, ew.work); parent = sdev->sdev_gendev.parent; - starget = to_scsi_target(parent); spin_lock_irqsave(sdev->host->host_lock, flags); - starget->reap_ref++; list_del(&sdev->siblings); list_del(&sdev->same_target_siblings); list_del(&sdev->starved_entry); @@ -413,8 +410,6 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) /* NULL queue means the device can't be used */ sdev->request_queue = NULL; - scsi_target_reap(scsi_target(sdev)); - kfree(sdev->inquiry); kfree(sdev); @@ -1071,6 +1066,13 @@ void __scsi_remove_device(struct scsi_device *sdev) sdev->host->hostt->slave_destroy(sdev); transport_destroy_device(dev); + /* + * Paired with the kref_get() in scsi_sysfs_initialize(). We have + * remoed sysfs visibility from the device, so make the target + * invisible if this was the last device underneath it. + */ + scsi_target_reap(scsi_target(sdev)); + put_device(dev); } @@ -1133,7 +1135,7 @@ void scsi_remove_target(struct device *dev) continue; if (starget->dev.parent == dev || &starget->dev == dev) { /* assuming new targets arrive at the end */ - starget->reap_ref++; + kref_get(&starget->reap_ref); spin_unlock_irqrestore(shost->host_lock, flags); if (last) scsi_target_reap(last); @@ -1217,6 +1219,12 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev) list_add_tail(&sdev->same_target_siblings, &starget->devices); list_add_tail(&sdev->siblings, &shost->__devices); spin_unlock_irqrestore(shost->host_lock, flags); + /* + * device can now only be removed via __scsi_remove_device() so hold + * the target. Target will be held in CREATED state until something + * beneath it becomes visible (in which case it moves to RUNNING) + */ + kref_get(&starget->reap_ref); } int scsi_is_sdev_device(const struct device *dev) diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 622e100561d2..ccabdc1c27ca 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -269,7 +269,7 @@ struct scsi_target { struct list_head siblings; struct list_head devices; struct device dev; - unsigned int reap_ref; /* protected by the host lock */ + struct kref reap_ref; /* last put renders target invisible */ unsigned int channel; unsigned int id; /* target id ... replace * scsi_device.id eventually */ @@ -296,7 +296,6 @@ struct scsi_target { #define SCSI_DEFAULT_TARGET_BLOCKED 3 char scsi_level; - struct execute_work ew; enum scsi_target_state state; void *hostdata; /* available to low-level driver */ unsigned long starget_data[0]; /* for the transport */ |