[PATCH] scsi host/scsi device ref count cleanup 3/4

[Mike Anderson <andmike@us.ibm.com>]

-andmike
--
Michael Anderson
andmike@us.ibm.com

DESC
This is a cleanup patch for scsi_host removal.
	- Addition of a host_flags member to the scsi_host strucuture to
	  contain "state" of the host instance.
	- Added SHOST_ADD, SHOST_DEL, SHOST_CANCEL, SHOST_RECOVERY states
	  for a scsi host
	- Addtion / rename of a new function scsi_host_cancel to cancel
	  IOs in flight.
	- Usage of the host_flags flags member to stop scsi_host_get's and
	  calls to LLDD queucommand under certain states.
	- Reordered some of the scsi host sysfs unregistration.
EDESC


 drivers/scsi/hosts.c       |   62 +++++++++++++++++++++++++++------------------
 drivers/scsi/scsi.c        |   31 +++++++++++++++-------
 drivers/scsi/scsi_debug.c  |    5 ---
 drivers/scsi/scsi_error.c  |    7 ++---
 drivers/scsi/scsi_lib.c    |    5 ++-
 drivers/scsi/scsi_proc.c   |   12 ++++----
 drivers/scsi/scsi_syms.c   |    2 -
 drivers/scsi/scsi_sysfs.c  |   44 ++++++++++++++++++++++---------
 drivers/scsi/sg.c          |    3 +-
 drivers/usb/storage/usb.c  |    7 -----
 include/scsi/scsi_device.h |    2 -
 include/scsi/scsi_host.h   |   16 +++++++++--
 12 files changed, 122 insertions(+), 74 deletions(-)

diff -puN drivers/scsi/hosts.c~shost_state drivers/scsi/hosts.c
--- remove-scsi-misc-2.5/drivers/scsi/hosts.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/hosts.c	Tue Jul  8 14:19:52 2003
@@ -39,30 +39,35 @@
 
 static int scsi_host_next_hn;		/* host_no for next new host */
 
+
 /**
- * scsi_remove_host - check a scsi host for release and release
- * @shost:	a pointer to a scsi host to release
- *
- * Return value:
- * 	0 on Success / 1 on Failure
+ * scsi_host_cancel - cancel outstanding IO to this host
+ * @shost:	pointer to struct Scsi_Host
+ * recovery:	recovery requested to run.
  **/
-int scsi_remove_host(struct Scsi_Host *shost)
+void scsi_host_cancel(struct Scsi_Host *shost, int recovery)
 {
-	struct scsi_device *sdev;
+	unsigned long flags;
 
-	/*
-	 * FIXME Do ref counting.  We force all of the devices offline to
-	 * help prevent race conditions where other hosts/processors could
-	 * try and get in and queue a command.
-	 */
-	list_for_each_entry(sdev, &shost->my_devices, siblings)
-		sdev->online = FALSE;
+	spin_lock_irqsave(shost->host_lock, flags);
+	__set_bit(SHOST_CANCEL, &shost->host_flags);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	device_for_each_child(&shost->host_gendev, &recovery,
+			      scsi_device_cancel);
+	wait_event(shost->host_wait, (!test_bit(SHOST_RECOVERY,
+						&shost->host_flags)));
+}
 
+/**
+ * scsi_remove_host - remove a scsi host
+ * @shost:	a pointer to a scsi host to remove
+ **/
+void scsi_remove_host(struct Scsi_Host *shost)
+{
+	scsi_host_cancel(shost, 0);
 	scsi_proc_host_rm(shost);
 	scsi_forget_host(shost);
 	scsi_sysfs_remove_host(shost);
-
-	return 0;
 }
 
 /**
@@ -93,7 +98,7 @@ int scsi_add_host(struct Scsi_Host *shos
 		scsi_proc_host_add(shost);
 		scsi_scan_host(shost);
 	}
-			
+
 	return error;
 }
 
@@ -259,21 +264,21 @@ struct Scsi_Host *scsi_host_lookup(unsig
 {
 	struct class *class = class_get(&shost_class);
 	struct class_device *cdev;
-	struct Scsi_Host *shost = NULL, *p;
+	struct Scsi_Host *shost = ERR_PTR(-ENXIO), *p;
 
 	if (class) {
 		down_read(&class->subsys.rwsem);
 		list_for_each_entry(cdev, &class->children, node) {
 			p = class_to_shost(cdev);
 			if (p->host_no == hostnum) {
-				scsi_host_get(p);
-				shost = p;
+				shost = scsi_host_get(p);
 				break;
 			}
 		}
 		up_read(&class->subsys.rwsem);
 	}
 
+	class_put(&shost_class);
 	return shost;
 }
 
@@ -281,10 +286,20 @@ struct Scsi_Host *scsi_host_lookup(unsig
  * *scsi_host_get - inc a Scsi_Host ref count
  * @shost:	Pointer to Scsi_Host to inc.
  **/
-void scsi_host_get(struct Scsi_Host *shost)
+struct Scsi_Host * scsi_host_get(struct Scsi_Host *shost)
 {
-	get_device(&shost->host_gendev);
-	class_device_get(&shost->class_dev);
+	struct Scsi_Host *res_shost = shost;
+
+	if (res_shost) {
+		if (!test_bit(SHOST_DEL, &shost->host_flags)) {
+			if (!get_device(&res_shost->host_gendev))
+				res_shost = ERR_PTR(-ENXIO);
+		} else {
+			res_shost = ERR_PTR(-ENXIO);
+		}
+	}
+
+	return res_shost;
 }
 
 /**
@@ -293,6 +308,5 @@ void scsi_host_get(struct Scsi_Host *sho
  **/
 void scsi_host_put(struct Scsi_Host *shost)
 {
-	class_device_put(&shost->class_dev);
 	put_device(&shost->host_gendev);
 }
diff -puN drivers/scsi/scsi.c~shost_state drivers/scsi/scsi.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi.c	Tue Jul  8 14:19:52 2003
@@ -370,7 +370,7 @@ int scsi_dispatch_cmd(struct scsi_cmnd *
 	struct Scsi_Host *host = cmd->device->host;
 	unsigned long flags = 0;
 	unsigned long timeout;
-	int rtn = 1;
+	int rtn = 0;
 
 	/* Assign a unique nonzero serial_number. */
 	/* XXX(hch): this is racy */
@@ -444,7 +444,12 @@ int scsi_dispatch_cmd(struct scsi_cmnd *
 				   host->hostt->queuecommand));
 
 	spin_lock_irqsave(host->host_lock, flags);
-	rtn = host->hostt->queuecommand(cmd, scsi_done);
+	if (unlikely(test_bit(SHOST_CANCEL, &host->host_flags))) {
+		cmd->result = (DID_NO_CONNECT << 16);
+		scsi_done(cmd);
+	} else {
+		rtn = host->hostt->queuecommand(cmd, scsi_done);
+	}
 	spin_unlock_irqrestore(host->host_lock, flags);
 	if (rtn) {
 		scsi_queue_insert(cmd,
@@ -902,17 +907,19 @@ void scsi_device_put(struct scsi_device 
 }
 
 /**
- * scsi_set_device_offline - set scsi_device offline
- * @sdev:	pointer to struct scsi_device to offline. 
+ * scsi_device_cancel - cancel outstanding IO to this device
+ * @sdev:	pointer to struct scsi_device
+ * @data:	pointer to cancel value.
  *
- * Locks:	host_lock held on entry.
  **/
-void scsi_set_device_offline(struct scsi_device *sdev)
+int scsi_device_cancel(struct device *dev, void *data)
 {
 	struct scsi_cmnd *scmd;
 	LIST_HEAD(active_list);
 	struct list_head *lh, *lh_sf;
 	unsigned long flags;
+	struct scsi_device *sdev = to_scsi_device(dev);
+	unsigned int recovery = *(unsigned int *)data;
 
 	sdev->online = 0;
 
@@ -934,11 +941,17 @@ void scsi_set_device_offline(struct scsi
 	if (!list_empty(&active_list)) {
 		list_for_each_safe(lh, lh_sf, &active_list) {
 			scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
-			scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
+			list_del_init(lh);
+			if (recovery) {
+				scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
+			} else {
+				scmd->result = (DID_ABORT << 16);
+				scsi_finish_command(scmd);
+			}
 		}
-	} else {
-		/* FIXME: Send online state change hotplug event */
 	}
+
+	return 0;
 }
 
 MODULE_DESCRIPTION("SCSI core");
diff -puN drivers/scsi/scsi_debug.c~shost_state drivers/scsi/scsi_debug.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi_debug.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi_debug.c	Tue Jul  8 14:19:52 2003
@@ -1721,10 +1721,7 @@ static int sdebug_driver_remove(struct d
 		return -ENODEV;
 	}
 
-        if (scsi_remove_host(sdbg_host->shost)) {
-                printk(KERN_ERR "%s: scsi_remove_host failed\n", __FUNCTION__);
-                return -EBUSY;
-        }
+        scsi_remove_host(sdbg_host->shost);
 
         list_for_each_safe(lh, lh_sf, &sdbg_host->dev_info_list) {
                 sdbg_devinfo = list_entry(lh, struct sdebug_dev_info,
diff -puN drivers/scsi/scsi_error.c~shost_state drivers/scsi/scsi_error.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi_error.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi_error.c	Tue Jul  8 14:19:52 2003
@@ -84,7 +84,7 @@ int scsi_eh_scmd_add(struct scsi_cmnd *s
 	 */
 	scmd->serial_number_at_timeout = scmd->serial_number;
 	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
-	shost->in_recovery = 1;
+	set_bit(SHOST_RECOVERY, &shost->host_flags);
 	shost->host_failed++;
 	scsi_eh_wakeup(shost);
 	spin_unlock_irqrestore(shost->host_lock, flags);
@@ -187,7 +187,7 @@ void scsi_times_out(struct scsi_cmnd *sc
  **/
 int scsi_block_when_processing_errors(struct scsi_device *sdev)
 {
-	wait_event(sdev->host->host_wait, (sdev->host->in_recovery == 0));
+	wait_event(sdev->host->host_wait, (!test_bit(SHOST_RECOVERY, &sdev->host->host_flags)));
 
 	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __FUNCTION__,
 					  sdev->online));
@@ -1389,7 +1389,7 @@ static void scsi_restart_operations(stru
 	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
 					  __FUNCTION__));
 
-	shost->in_recovery = 0;
+	clear_bit(SHOST_RECOVERY, &shost->host_flags);
 
 	wake_up(&shost->host_wait);
 
@@ -1599,7 +1599,6 @@ void scsi_error_handler(void *data)
 	 * that's fine.  If the user sent a signal to this thing, we are
 	 * potentially in real danger.
 	 */
-	shost->in_recovery = 0;
 	shost->eh_active = 0;
 	shost->ehandler = NULL;
 
diff -puN drivers/scsi/scsi_lib.c~shost_state drivers/scsi/scsi_lib.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi_lib.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi_lib.c	Tue Jul  8 14:19:52 2003
@@ -318,7 +318,8 @@ void scsi_device_unbusy(struct scsi_devi
 
 	spin_lock_irqsave(shost->host_lock, flags);
 	shost->host_busy--;
-	if (unlikely(shost->in_recovery && shost->host_failed))
+	if (unlikely(test_bit(SHOST_RECOVERY, &shost->host_flags) &&
+		     shost->host_failed))
 		scsi_eh_wakeup(shost);
 	spin_unlock(shost->host_lock);
 	spin_lock(&sdev->sdev_lock);
@@ -1080,7 +1081,7 @@ static inline int scsi_host_queue_ready(
 				   struct Scsi_Host *shost,
 				   struct scsi_device *sdev)
 {
-	if (shost->in_recovery)
+	if (test_bit(SHOST_RECOVERY, &shost->host_flags))
 		return 0;
 	if (shost->host_busy == 0 && shost->host_blocked) {
 		/*
diff -puN drivers/scsi/scsi_proc.c~shost_state drivers/scsi/scsi_proc.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi_proc.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi_proc.c	Tue Jul  8 14:19:52 2003
@@ -190,11 +190,11 @@ static int scsi_add_single_device(uint h
 {
 	struct Scsi_Host *shost;
 	struct scsi_device *sdev;
-	int error = -ENODEV;
+	int error = -ENXIO;
 
 	shost = scsi_host_lookup(host);
-	if (!shost)
-		return -ENODEV;
+	if (IS_ERR(shost))
+		return PTR_ERR(shost);
 
 	if (!scsi_find_device(shost, channel, id, lun)) {
 		sdev = scsi_add_device(shost, channel, id, lun);
@@ -212,11 +212,11 @@ static int scsi_remove_single_device(uin
 {
 	struct scsi_device *sdev;
 	struct Scsi_Host *shost;
-	int error = -ENODEV;
+	int error = -ENXIO;
 
 	shost = scsi_host_lookup(host);
-	if (!shost)
-		return -ENODEV;
+	if (IS_ERR(shost))
+		return PTR_ERR(shost);
 	sdev = scsi_find_device(shost, channel, id, lun);
 	if (!sdev)
 		goto out;
diff -puN drivers/scsi/scsi_syms.c~shost_state drivers/scsi/scsi_syms.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi_syms.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi_syms.c	Tue Jul  8 14:19:52 2003
@@ -85,7 +85,7 @@ EXPORT_SYMBOL(scsi_device_get);
 EXPORT_SYMBOL(scsi_device_put);
 EXPORT_SYMBOL(scsi_add_device);
 EXPORT_SYMBOL(scsi_remove_device);
-EXPORT_SYMBOL(scsi_set_device_offline);
+EXPORT_SYMBOL(scsi_device_cancel);
 
 EXPORT_SYMBOL(__scsi_mode_sense);
 EXPORT_SYMBOL(scsi_mode_sense);
diff -puN drivers/scsi/scsi_sysfs.c~shost_state drivers/scsi/scsi_sysfs.c
--- remove-scsi-misc-2.5/drivers/scsi/scsi_sysfs.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/scsi_sysfs.c	Tue Jul  8 14:19:52 2003
@@ -44,6 +44,7 @@ shost_rd_attr(host_busy, "%hu\n");
 shost_rd_attr(cmd_per_lun, "%hd\n");
 shost_rd_attr(sg_tablesize, "%hu\n");
 shost_rd_attr(unchecked_isa_dma, "%d\n");
+shost_rd_attr(host_flags, "%lx\n");
 
 struct class_device_attribute *scsi_sysfs_shost_attrs[] = {
 	&class_device_attr_unique_id,
@@ -51,11 +52,30 @@ struct class_device_attribute *scsi_sysf
 	&class_device_attr_cmd_per_lun,
 	&class_device_attr_sg_tablesize,
 	&class_device_attr_unchecked_isa_dma,
+	&class_device_attr_host_flags,
 	NULL
 };
 
+static void scsi_host_cls_release(struct class_device *class_dev)
+{
+	struct Scsi_Host *shost;
+
+	shost = class_to_shost(class_dev);
+	put_device(&shost->host_gendev);
+}
+
+static void scsi_host_dev_release(struct device *dev)
+{
+	struct Scsi_Host *shost;
+
+	device_del(dev);
+	shost = dev_to_shost(dev);
+	scsi_free_shost(shost);
+}
+
 struct class shost_class = {
 	.name		= "scsi_host",
+	.release	= scsi_host_cls_release,
 };
 
 static struct class sdev_class = {
@@ -302,16 +322,6 @@ int scsi_register_interface(struct class
 	return class_interface_register(intf);
 }
 
-static void scsi_host_release(struct device *dev)
-{
-	struct Scsi_Host *shost;
-
-	shost = dev_to_shost(dev);
-	if (!shost)
-		return;
-
-	scsi_free_shost(shost);
-}
 
 void scsi_sysfs_init_host(struct Scsi_Host *shost)
 {
@@ -320,13 +330,14 @@ void scsi_sysfs_init_host(struct Scsi_Ho
 		shost->host_no);
 	snprintf(shost->host_gendev.name, DEVICE_NAME_SIZE, "%s",
 		shost->hostt->proc_name);
-	shost->host_gendev.release = scsi_host_release;
+	shost->host_gendev.release = scsi_host_dev_release;
 
 	class_device_initialize(&shost->class_dev);
 	shost->class_dev.dev = &shost->host_gendev;
 	shost->class_dev.class = &shost_class;
 	snprintf(shost->class_dev.class_id, BUS_ID_SIZE, "host%d",
 		  shost->host_no);
+	get_device(&shost->host_gendev);
 }
 
 /**
@@ -355,6 +366,8 @@ int scsi_sysfs_add_host(struct Scsi_Host
 	if (error)
 		goto clean_class;
 
+	set_bit(SHOST_ADD, &shost->host_flags);
+
 	return error;
 
 clean_class:
@@ -371,8 +384,13 @@ clean_device:
  **/
 void scsi_sysfs_remove_host(struct Scsi_Host *shost)
 {
-	class_device_del(&shost->class_dev);
-	device_del(&shost->host_gendev);
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	__set_bit(SHOST_DEL, &shost->host_flags);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	class_device_unregister(&shost->class_dev);
 }
 
 /** scsi_sysfs_modify_shost_attribute - modify or add a host class attribute
diff -puN drivers/scsi/sg.c~shost_state drivers/scsi/sg.c
--- remove-scsi-misc-2.5/drivers/scsi/sg.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/scsi/sg.c	Tue Jul  8 14:19:52 2003
@@ -954,7 +954,8 @@ sg_ioctl(struct inode *inode, struct fil
 		if (sdp->detached)
 			return -ENODEV;
 		if (filp->f_flags & O_NONBLOCK) {
-			if (sdp->device->host->in_recovery)
+			if (test_bit(SHOST_RECOVERY,
+				     &sdp->device->host->host_flags))
 				return -EBUSY;
 		} else if (!scsi_block_when_processing_errors(sdp->device))
 			return -EBUSY;
diff -puN include/scsi/scsi_device.h~shost_state include/scsi/scsi_device.h
--- remove-scsi-misc-2.5/include/scsi/scsi_device.h~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/include/scsi/scsi_device.h	Tue Jul  8 14:19:52 2003
@@ -94,7 +94,7 @@ struct scsi_device {
 extern struct scsi_device *scsi_add_device(struct Scsi_Host *,
 		uint, uint, uint);
 extern int scsi_remove_device(struct scsi_device *);
-extern void scsi_set_device_offline(struct scsi_device *);
+extern int scsi_device_cancel(struct device *, void *);
 
 extern int scsi_device_get(struct scsi_device *);
 extern void scsi_device_put(struct scsi_device *);
diff -puN include/scsi/scsi_host.h~shost_state include/scsi/scsi_host.h
--- remove-scsi-misc-2.5/include/scsi/scsi_host.h~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/include/scsi/scsi_host.h	Tue Jul  8 14:19:52 2003
@@ -348,6 +348,14 @@ struct scsi_host_template {
 	struct list_head legacy_hosts;
 };
 
+/*
+ * shost flags
+ */
+#define SHOST_ADD	1
+#define SHOST_DEL	2
+#define SHOST_CANCEL	3
+#define SHOST_RECOVERY	4
+
 struct Scsi_Host {
 	struct list_head	my_devices;
 	struct scsi_host_cmd_pool *cmd_pool;
@@ -413,7 +421,6 @@ struct Scsi_Host {
 	short unsigned int sg_tablesize;
 	short unsigned int max_sectors;
 
-	unsigned in_recovery:1;
 	unsigned unchecked_isa_dma:1;
 	unsigned use_clustering:1;
 	unsigned highmem_io:1;
@@ -454,6 +461,9 @@ struct Scsi_Host {
 	unsigned char n_io_port;
 	unsigned char dma_channel;
 	unsigned int  irq;
+	
+
+	unsigned long host_flags;
 
 
 	/*
@@ -480,8 +490,8 @@ struct Scsi_Host {
 
 extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int);
 extern int scsi_add_host(struct Scsi_Host *, struct device *);
-extern int scsi_remove_host(struct Scsi_Host *);
-extern void scsi_host_get(struct Scsi_Host *);
+extern void scsi_remove_host(struct Scsi_Host *);
+extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
 extern void scsi_host_put(struct Scsi_Host *t);
 extern struct Scsi_Host *scsi_host_lookup(unsigned short);
 
diff -puN drivers/usb/storage/usb.c~shost_state drivers/usb/storage/usb.c
--- remove-scsi-misc-2.5/drivers/usb/storage/usb.c~shost_state	Tue Jul  8 14:19:52 2003
+++ remove-scsi-misc-2.5-andmike/drivers/usb/storage/usb.c	Tue Jul  8 14:19:52 2003
@@ -993,12 +993,7 @@ static void storage_disconnect(struct us
 	/* Dissociate from the USB device */
 	dissociate_dev(us);
 
-	/* Begin the SCSI host removal sequence */
-	if (scsi_remove_host(us->host)) {
-		US_DEBUGP("-- SCSI refused to remove the host\n");
-		BUG();
-		return;
-	}
+	scsi_remove_host(us->host);
 
 	/* TODO: somehow, wait for the device to
 	 * be 'idle' (tasklet completion) */

_