# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.1482  -> 1.1483 
#	include/scsi/scsi_device.h	1.10    -> 1.11   
#	drivers/scsi/scsi_sysfs.c	1.37    -> 1.38   
#	drivers/scsi/scsi_lib.c	1.114   -> 1.115  
#	 drivers/scsi/scsi.c	1.130   -> 1.131  
#	drivers/scsi/scsi_scan.c	1.113   -> 1.114  
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/11/22	jejb@raven.il.steeleye.com	1.1483
# Updated state model for SCSI devices
# 
# I've been looking at enforcing lifetime phases for SCSI devices
# (primarily to try to get the mid layer to offload as much of the device
# creation and hotplug pieces as it can).
# 
# I've hijacked the sdev_state field of the struct scsi_device (formerly
# this was a bitmap, now it becomes an enumerated state).
# 
# I've also begun adding references sdev_gendev into the code to pin the
# scsi_device---initially in the queue function, but possibly this should
# also be done in the scsi_command_get/put, the idea being to prevent
# scsi_device freeing while there's still device activity.
# 
# The object phases I identified are:
# 
# 1. SDEV_CREATED - we've just allocated the device.  It may respond to
# internally generated commands, but not to user ones (the user should
# actually have no way to access a device in this state, but just in
# case).
# 
# 2. SDEV_RUNNING - the device is fully operational
# 
# 3. SDEV_CANCEL - The device is cleanly shutting down.  It may respond to
# internally generated commands (for cancellation/recovery) only; all user
# commands are errored unless they have already been queued (QUEUE_FULL
# handling and the like).
# 
# 4. SDEV_DEL - The device is gone. *all* commands are errored out.
# 
# Ordinarily, the device should move through all four phases from creation
# to destruction, but moving SDEV_RUNNING->SDEV_DEL because of surprise
# ejection should work.
# 
# It's starting to look like the online flag should be absorbed into this
# (offlined devices move essentially to SDEV_CANCEL and could be
# reactivated by moving to SDEV_RUNNING).
# 
# I haven't altered the similar bitmap model that scsi_host has, although
# this too should probably move to an enumerated state model.
# 
# I've tested this by physically yanking a module out from underneath a
# running filesystem with no ill effects (other than a slew of I/O
# errors).
# 
# The obvious problem is that this kills possible user error handling, but
# we don't do any of that yet.
# --------------------------------------------
#
diff -Nru a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
--- a/drivers/scsi/scsi.c	Mon Nov 24 17:27:26 2003
+++ b/drivers/scsi/scsi.c	Mon Nov 24 17:27:26 2003
@@ -367,6 +367,16 @@
 	unsigned long timeout;
 	int rtn = 0;
 
+	/* check if the device is still usable */
+	if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
+		/* in SDEV_DEL we error all commands. DID_NO_CONNECT
+		 * returns an immediate error upwards, and signals
+		 * that the device is no longer present */
+		cmd->result = DID_NO_CONNECT << 16;
+		scsi_done(cmd);
+		/* return 0 (because the command has been processed) */
+		goto out;
+	}
 	/* Assign a unique nonzero serial_number. */
 	/* XXX(hch): this is racy */
 	if (++serial_number == 0)
@@ -893,7 +903,7 @@
  */
 int scsi_device_get(struct scsi_device *sdev)
 {
-	if (test_bit(SDEV_DEL, &sdev->sdev_state))
+	if (sdev->sdev_state == SDEV_DEL)
 		return -ENXIO;
 	if (!get_device(&sdev->sdev_gendev))
 		return -ENXIO;
@@ -1015,7 +1025,7 @@
 	struct list_head *lh, *lh_sf;
 	unsigned long flags;
 
-	set_bit(SDEV_CANCEL, &sdev->sdev_state);
+	sdev->sdev_state = SDEV_CANCEL;
 
 	spin_lock_irqsave(&sdev->list_lock, flags);
 	list_for_each_entry(scmd, &sdev->cmd_list, list) {
diff -Nru a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
--- a/drivers/scsi/scsi_lib.c	Mon Nov 24 17:27:26 2003
+++ b/drivers/scsi/scsi_lib.c	Mon Nov 24 17:27:26 2003
@@ -923,6 +923,22 @@
 {
 	struct scsi_device *sdev = q->queuedata;
 	struct scsi_cmnd *cmd;
+	int specials_only = 0;
+
+	if(unlikely(sdev->sdev_state != SDEV_RUNNING)) {
+		/* OK, we're not in a running state don't prep
+		 * user commands */
+		if(sdev->sdev_state == SDEV_DEL) {
+			/* Device is fully deleted, no commands
+			 * at all allowed down */
+			printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
+			       sdev->host->host_no, sdev->id, sdev->lun);
+			return BLKPREP_KILL;
+		}
+		/* OK, we only allow special commands (i.e. not
+		 * user initiated ones */
+		specials_only = 1;
+	}
 
 	/*
 	 * Find the actual device driver associated with this command.
@@ -945,6 +961,14 @@
 		} else
 			cmd = req->special;
 	} else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
+
+		if(unlikely(specials_only)) {
+			printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
+			       sdev->host->host_no, sdev->id, sdev->lun);
+			return BLKPREP_KILL;
+		}
+			
+			
 		/*
 		 * Just check to see if the device is online.  If
 		 * it isn't, we refuse to process ordinary commands
@@ -1127,6 +1151,10 @@
 	struct scsi_cmnd *cmd;
 	struct request *req;
 
+	if(!get_device(&sdev->sdev_gendev))
+		/* We must be tearing the block queue down already */
+		return;
+
 	/*
 	 * To start with, we keep looping until the queue is empty, or until
 	 * the host is no longer able to accept any more requests.
@@ -1199,7 +1227,7 @@
 		}
 	}
 
-	return;
+	goto out;
 
  not_ready:
 	spin_unlock_irq(shost->host_lock);
@@ -1217,6 +1245,12 @@
 	sdev->device_busy--;
 	if(sdev->device_busy == 0)
 		blk_plug_device(q);
+ out:
+	/* must be careful here...if we trigger the ->remove() function
+	 * we cannot be holding the q lock */
+	spin_unlock_irq(q->queue_lock);
+	put_device(&sdev->sdev_gendev);
+	spin_lock_irq(q->queue_lock);
 }
 
 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
diff -Nru a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
--- a/drivers/scsi/scsi_scan.c	Mon Nov 24 17:27:26 2003
+++ b/drivers/scsi/scsi_scan.c	Mon Nov 24 17:27:26 2003
@@ -205,6 +205,7 @@
 	sdev->lun = lun;
 	sdev->channel = channel;
 	sdev->online = TRUE;
+	sdev->sdev_state = SDEV_CREATED;
 	INIT_LIST_HEAD(&sdev->siblings);
 	INIT_LIST_HEAD(&sdev->same_target_siblings);
 	INIT_LIST_HEAD(&sdev->cmd_list);
diff -Nru a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
--- a/drivers/scsi/scsi_sysfs.c	Mon Nov 24 17:27:26 2003
+++ b/drivers/scsi/scsi_sysfs.c	Mon Nov 24 17:27:26 2003
@@ -346,9 +346,11 @@
 {
 	int error = -EINVAL, i;
 
-	if (test_and_set_bit(SDEV_ADD, &sdev->sdev_state))
+	if (sdev->sdev_state != SDEV_CREATED)
 		return error;
 
+	sdev->sdev_state = SDEV_RUNNING;
+
 	error = device_add(&sdev->sdev_gendev);
 	if (error) {
 		printk(KERN_INFO "error 1\n");
@@ -386,8 +388,11 @@
 	return error;
 
 clean_device:
+	sdev->sdev_state = SDEV_CANCEL;
+
 	device_del(&sdev->sdev_gendev);
 	put_device(&sdev->sdev_gendev);
+
 	return error;
 
 }
@@ -398,8 +403,8 @@
  **/
 void scsi_remove_device(struct scsi_device *sdev)
 {
-	if (test_and_clear_bit(SDEV_ADD, &sdev->sdev_state)) {
-		set_bit(SDEV_DEL, &sdev->sdev_state);
+	if (sdev->sdev_state == SDEV_RUNNING || sdev->sdev_state == SDEV_CANCEL) {
+		sdev->sdev_state = SDEV_DEL;
 		class_device_unregister(&sdev->sdev_classdev);
 		device_del(&sdev->sdev_gendev);
 		if (sdev->host->hostt->slave_destroy)
diff -Nru a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
--- a/include/scsi/scsi_device.h	Mon Nov 24 17:27:26 2003
+++ b/include/scsi/scsi_device.h	Mon Nov 24 17:27:26 2003
@@ -14,11 +14,15 @@
 /*
  * sdev state
  */
-enum {
-	SDEV_ADD,
-	SDEV_DEL,
-	SDEV_CANCEL,
-	SDEV_RECOVERY,
+enum scsi_device_state {
+	SDEV_CREATED,		/* device created but not added to sysfs
+				 * Only internal commands allowed (for inq) */
+	SDEV_RUNNING,		/* device properly configured
+				 * All commands allowed */
+	SDEV_CANCEL,		/* beginning to delete device
+				 * Only error handler commands allowed */
+	SDEV_DEL,		/* device deleted 
+				 * no commands allowed */
 };
 
 struct scsi_device {
@@ -99,7 +103,7 @@
 	struct device		sdev_gendev;
 	struct class_device	sdev_classdev;
 
-	unsigned long sdev_state;
+	enum scsi_device_state sdev_state;
 };
 #define	to_scsi_device(d)	\
 	container_of(d, struct scsi_device, sdev_gendev)