Re: [PATCH scsi-misc-2.6 04/13] scsi: remove meaningless volatile qualifiers from structure definitions

[Tejun Heo <htejun@gmail.com>]

04_scsi_remove_volatile.patch

	scsi_device->device_busy, Scsi_Host->host_busy and
	->host_failed have volatile qualifiers, but the qualifiers
	don't serve any purpose.  Kill them.  While at it, protect
	->host_failed update in scsi_error for consistency and clarity.

Signed-off-by: Tejun Heo <htejun@gmail.com>

 scsi_device.h |    3 ++-
 scsi_host.h   |   10 ++++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

Index: scsi-export/include/scsi/scsi_device.h
===================================================================
--- scsi-export.orig/include/scsi/scsi_device.h	2005-03-31 17:42:05.000000000 +0900
+++ scsi-export/include/scsi/scsi_device.h	2005-03-31 18:06:20.000000000 +0900
@@ -43,7 +43,8 @@ struct scsi_device {
 	struct list_head    siblings;   /* list of all devices on this host */
 	struct list_head    same_target_siblings; /* just the devices sharing same target id */
 
-	volatile unsigned short device_busy;	/* commands actually active on low-level */
+	unsigned short device_busy;	/* commands actually active on
+					 * low-level. protected by sdev_lock. */
 	spinlock_t sdev_lock;           /* also the request queue_lock */
 	spinlock_t list_lock;
 	struct list_head cmd_list;	/* queue of in use SCSI Command structures */
Index: scsi-export/include/scsi/scsi_host.h
===================================================================
--- scsi-export.orig/include/scsi/scsi_host.h	2005-03-31 17:42:05.000000000 +0900
+++ scsi-export/include/scsi/scsi_host.h	2005-03-31 18:06:20.000000000 +0900
@@ -448,8 +448,14 @@ struct Scsi_Host {
 	wait_queue_head_t       host_wait;
 	struct scsi_host_template *hostt;
 	struct scsi_transport_template *transportt;
-	volatile unsigned short host_busy;   /* commands actually active on low-level */
-	volatile unsigned short host_failed; /* commands that failed. */
+
+	/*
+	 * The following two fields are protected with host_lock;
+	 * however, eh routines can safely access during eh processing
+	 * without acquiring the lock.
+	 */
+	unsigned short host_busy;	   /* commands actually active on low-level */
+	unsigned short host_failed;	   /* commands that failed. */
     
 	unsigned short host_no;  /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */
 	int resetting; /* if set, it means that last_reset is a valid value */