scsi: ipr: System hung while dlpar adding primary ipr adapter back

While dlpar adding primary ipr adapter back, driver goes through adapter
initialization then schedule ipr_worker_thread to start te disk scan by
dropping the host lock, calling scsi_add_device.  Then get the adapter reset
request again, so driver does scsi_block_requests, this will cause the
scsi_add_device get hung until we unblock. But we can't run ipr_worker_thread
to do the unblock because its stuck in scsi_add_device.

This patch fixes the issue.

[mkp: typo and whitespace fixes]

Signed-off-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

2 files changed, 62 insertions, 45 deletions

diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index f2ec80b0ffc0..271990bc065b 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -3335,6 +3335,65 @@ static void ipr_release_dump(struct kref *kref)
         LEAVE;
 }
 
+static void ipr_add_remove_thread(struct work_struct *work)
+{
+        unsigned long lock_flags;
+        struct ipr_resource_entry *res;
+        struct scsi_device *sdev;
+        struct ipr_ioa_cfg *ioa_cfg =
+                container_of(work, struct ipr_ioa_cfg, scsi_add_work_q);
+        u8 bus, target, lun;
+        int did_work;
+
+        ENTER;
+        spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
+
+restart:
+        do {
+                did_work = 0;
+                if (!ioa_cfg->hrrq[IPR_INIT_HRRQ].allow_cmds) {
+                        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
+                        return;
+                }
+
+                list_for_each_entry(res, &ioa_cfg->used_res_q, queue) {
+                        if (res->del_from_ml && res->sdev) {
+                                did_work = 1;
+                                sdev = res->sdev;
+                                if (!scsi_device_get(sdev)) {
+                                        if (!res->add_to_ml)
+                                                list_move_tail(&res->queue, &ioa_cfg->free_res_q);
+                                        else
+                                                res->del_from_ml = 0;
+                                        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
+                                        scsi_remove_device(sdev);
+                                        scsi_device_put(sdev);
+                                        spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
+                                }
+                                break;
+                        }
+                }
+        } while (did_work);
+
+        list_for_each_entry(res, &ioa_cfg->used_res_q, queue) {
+                if (res->add_to_ml) {
+                        bus = res->bus;
+                        target = res->target;
+                        lun = res->lun;
+                        res->add_to_ml = 0;
+                        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
+                        scsi_add_device(ioa_cfg->host, bus, target, lun);
+                        spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
+                        goto restart;
+                }
+        }
+
+        ioa_cfg->scan_done = 1;
+        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
+        kobject_uevent(&ioa_cfg->host->shost_dev.kobj, KOBJ_CHANGE);
+        LEAVE;
+}
+
 /**
  * ipr_worker_thread - Worker thread
  * @work:               ioa config struct
@@ -3349,13 +3408,9 @@ static void ipr_release_dump(struct kref *kref)
 static void ipr_worker_thread(struct work_struct *work)
 {
         unsigned long lock_flags;
-        struct ipr_resource_entry *res;
-        struct scsi_device *sdev;
         struct ipr_dump *dump;
         struct ipr_ioa_cfg *ioa_cfg =
                 container_of(work, struct ipr_ioa_cfg, work_q);
-        u8 bus, target, lun;
-        int did_work;
 
         ENTER;
         spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
@@ -3393,49 +3448,9 @@ static void ipr_worker_thread(struct work_struct *work)
                 return;
         }
 
-restart:
-        do {
-                did_work = 0;
-                if (!ioa_cfg->hrrq[IPR_INIT_HRRQ].allow_cmds) {
-                        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
-                        return;
-                }
+        schedule_work(&ioa_cfg->scsi_add_work_q);
 
-                list_for_each_entry(res, &ioa_cfg->used_res_q, queue) {
-                        if (res->del_from_ml && res->sdev) {
-                                did_work = 1;
-                                sdev = res->sdev;
-                                if (!scsi_device_get(sdev)) {
-                                        if (!res->add_to_ml)
-                                                list_move_tail(&res->queue, &ioa_cfg->free_res_q);
-                                        else
-                                                res->del_from_ml = 0;
-                                        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
-                                        scsi_remove_device(sdev);
-                                        scsi_device_put(sdev);
-                                        spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
-                                }
-                                break;
-                        }
-                }
-        } while (did_work);
-
-        list_for_each_entry(res, &ioa_cfg->used_res_q, queue) {
-                if (res->add_to_ml) {
-                        bus = res->bus;
-                        target = res->target;
-                        lun = res->lun;
-                        res->add_to_ml = 0;
-                        spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
-                        scsi_add_device(ioa_cfg->host, bus, target, lun);
-                        spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
-                        goto restart;
-                }
-        }
-
-        ioa_cfg->scan_done = 1;
         spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
-        kobject_uevent(&ioa_cfg->host->shost_dev.kobj, KOBJ_CHANGE);
         LEAVE;
 }
 
@@ -9933,6 +9948,7 @@ static void ipr_init_ioa_cfg(struct ipr_ioa_cfg *ioa_cfg,
         INIT_LIST_HEAD(&ioa_cfg->free_res_q);
         INIT_LIST_HEAD(&ioa_cfg->used_res_q);
         INIT_WORK(&ioa_cfg->work_q, ipr_worker_thread);
+        INIT_WORK(&ioa_cfg->scsi_add_work_q, ipr_add_remove_thread);
         init_waitqueue_head(&ioa_cfg->reset_wait_q);
         init_waitqueue_head(&ioa_cfg->msi_wait_q);
         init_waitqueue_head(&ioa_cfg->eeh_wait_q);
diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
index 68afbbde54d3..f6baa2351313 100644
--- a/drivers/scsi/ipr.h
+++ b/drivers/scsi/ipr.h
@@ -1575,6 +1575,7 @@ struct ipr_ioa_cfg {
         u8 saved_mode_page_len;
 
         struct work_struct work_q;
+        struct work_struct scsi_add_work_q;
         struct workqueue_struct *reset_work_q;
 
         wait_queue_head_t reset_wait_q;