[SCSI] fix oops on usb storage device disconnect

We fix the oops by enforcing the host state model.  There have also
been two extra states added: SHOST_CANCEL_RECOVERY and
SHOST_DEL_RECOVERY so we can take the model through host removal while
the recovery thread is active.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

7 files changed, 57 insertions, 16 deletions

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 85503fad789a..f2a72d33132c 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -98,6 +98,7 @@ int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
                 switch (oldstate) {
                 case SHOST_CREATED:
                 case SHOST_RUNNING:
+                case SHOST_CANCEL_RECOVERY:
                         break;
                 default:
                         goto illegal;
@@ -107,12 +108,31 @@ int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
         case SHOST_DEL:
                 switch (oldstate) {
                 case SHOST_CANCEL:
+                case SHOST_DEL_RECOVERY:
                         break;
                 default:
                         goto illegal;
                 }
                 break;
 
+        case SHOST_CANCEL_RECOVERY:
+                switch (oldstate) {
+                case SHOST_CANCEL:
+                case SHOST_RECOVERY:
+                        break;
+                default:
+                        goto illegal;
+                }
+                break;
+
+        case SHOST_DEL_RECOVERY:
+                switch (oldstate) {
+                case SHOST_CANCEL_RECOVERY:
+                        break;
+                default:
+                        goto illegal;
+                }
+                break;
         }
         shost->shost_state = state;
         return 0;
@@ -134,13 +154,24 @@ EXPORT_SYMBOL(scsi_host_set_state);
  **/
 void scsi_remove_host(struct Scsi_Host *shost)
 {
+        unsigned long flags;
         down(&shost->scan_mutex);
-        scsi_host_set_state(shost, SHOST_CANCEL);
+        spin_lock_irqsave(shost->host_lock, flags);
+        if (scsi_host_set_state(shost, SHOST_CANCEL))
+                if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
+                        spin_unlock_irqrestore(shost->host_lock, flags);
+                        up(&shost->scan_mutex);
+                        return;
+                }
+        spin_unlock_irqrestore(shost->host_lock, flags);
         up(&shost->scan_mutex);
         scsi_forget_host(shost);
         scsi_proc_host_rm(shost);
 
-        scsi_host_set_state(shost, SHOST_DEL);
+        spin_lock_irqsave(shost->host_lock, flags);
+        if (scsi_host_set_state(shost, SHOST_DEL))
+                BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
+        spin_unlock_irqrestore(shost->host_lock, flags);
 
         transport_unregister_device(&shost->shost_gendev);
         class_device_unregister(&shost->shost_classdev);
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index a780546eda9c..1f0ebabf6d47 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -1265,9 +1265,8 @@ int scsi_device_cancel(struct scsi_device *sdev, int recovery)
                 list_for_each_safe(lh, lh_sf, &active_list) {
                         scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
                         list_del_init(lh);
-                        if (recovery) {
-                                scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
-                        } else {
+                        if (recovery &&
+                            !scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD)) {
                                 scmd->result = (DID_ABORT << 16);
                                 scsi_finish_command(scmd);
                         }
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 895c9452be4c..af589fac814d 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -68,19 +68,24 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
 {
         struct Scsi_Host *shost = scmd->device->host;
         unsigned long flags;
+        int ret = 0;
 
         if (shost->eh_wait == NULL)
                 return 0;
 
         spin_lock_irqsave(shost->host_lock, flags);
+        if (scsi_host_set_state(shost, SHOST_RECOVERY))
+                if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
+                        goto out_unlock;
 
+        ret = 1;
         scmd->eh_eflags |= eh_flag;
         list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
-        scsi_host_set_state(shost, SHOST_RECOVERY);
         shost->host_failed++;
         scsi_eh_wakeup(shost);
+ out_unlock:
         spin_unlock_irqrestore(shost->host_lock, flags);
-        return 1;
+        return ret;
 }
 
 /**
@@ -176,8 +181,8 @@ void scsi_times_out(struct scsi_cmnd *scmd)
                 }
 
         if (unlikely(!scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
-                panic("Error handler thread not present at %p %p %s %d",
-                      scmd, scmd->device->host, __FILE__, __LINE__);
+                scmd->result |= DID_TIME_OUT << 16;
+                __scsi_done(scmd);
         }
 }
 
@@ -196,8 +201,7 @@ int scsi_block_when_processing_errors(struct scsi_device *sdev)
 {
         int online;
 
-        wait_event(sdev->host->host_wait, (sdev->host->shost_state !=
-                                           SHOST_RECOVERY));
+        wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
 
         online = scsi_device_online(sdev);
 
@@ -1441,6 +1445,7 @@ static void scsi_eh_lock_door(struct scsi_device *sdev)
 static void scsi_restart_operations(struct Scsi_Host *shost)
 {
         struct scsi_device *sdev;
+        unsigned long flags;
 
         /*
          * If the door was locked, we need to insert a door lock request
@@ -1460,7 +1465,11 @@ static void scsi_restart_operations(struct Scsi_Host *shost)
         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
                                           __FUNCTION__));
 
-        scsi_host_set_state(shost, SHOST_RUNNING);
+        spin_lock_irqsave(shost->host_lock, flags);
+        if (scsi_host_set_state(shost, SHOST_RUNNING))
+                if (scsi_host_set_state(shost, SHOST_CANCEL))
+                        BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
+        spin_unlock_irqrestore(shost->host_lock, flags);
 
         wake_up(&shost->host_wait);
 
diff --git a/drivers/scsi/scsi_ioctl.c b/drivers/scsi/scsi_ioctl.c
index b7fddac81347..de7f98cc38fe 100644
--- a/drivers/scsi/scsi_ioctl.c
+++ b/drivers/scsi/scsi_ioctl.c
@@ -458,7 +458,7 @@ int scsi_nonblockable_ioctl(struct scsi_device *sdev, int cmd,
          * error processing, as long as the device was opened
          * non-blocking */
         if (filp && filp->f_flags & O_NONBLOCK) {
-                if (sdev->host->shost_state == SHOST_RECOVERY)
+                if (scsi_host_in_recovery(sdev->host))
                         return -ENODEV;
         } else if (!scsi_block_when_processing_errors(sdev))
                 return -ENODEV;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f065cbc1a6e5..dc9c772bc874 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -447,7 +447,7 @@ void scsi_device_unbusy(struct scsi_device *sdev)
 
         spin_lock_irqsave(shost->host_lock, flags);
         shost->host_busy--;
-        if (unlikely((shost->shost_state == SHOST_RECOVERY) &&
+        if (unlikely(scsi_host_in_recovery(shost) &&
                      shost->host_failed))
                 scsi_eh_wakeup(shost);
         spin_unlock(shost->host_lock);
@@ -1339,7 +1339,7 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
                                    struct Scsi_Host *shost,
                                    struct scsi_device *sdev)
 {
-        if (shost->shost_state == SHOST_RECOVERY)
+        if (scsi_host_in_recovery(shost))
                 return 0;
         if (shost->host_busy == 0 && shost->host_blocked) {
                 /*
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 1e47b7eddef4..72a6550a056c 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -57,6 +57,8 @@ static struct {
         { SHOST_CANCEL, "cancel" },
         { SHOST_DEL, "deleted" },
         { SHOST_RECOVERY, "recovery" },
+        { SHOST_CANCEL_RECOVERY, "cancel/recovery" },
+        { SHOST_DEL_RECOVERY, "deleted/recovery", },
 };
 const char *scsi_host_state_name(enum scsi_host_state state)
 {
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 9ea4765d1d12..4d09a6e4dd2e 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1027,7 +1027,7 @@ sg_ioctl(struct inode *inode, struct file *filp,
                 if (sdp->detached)
                         return -ENODEV;
                 if (filp->f_flags & O_NONBLOCK) {
-                        if (sdp->device->host->shost_state == SHOST_RECOVERY)
+                        if (scsi_host_in_recovery(sdp->device->host))
                                 return -EBUSY;
                 } else if (!scsi_block_when_processing_errors(sdp->device))
                         return -EBUSY;