ide: remove hwgroup->hwif and {drive,hwif}->next

* Add 'int port_count' field to ide_hwgroup_t to keep the track
  of the number of ports in the hwgroup.  Then update init_irq()
  and ide_remove_port_from_hwgroup() to use it.

* Remove no longer needed hwgroup->hwif, {drive,hwif}->next,
  ide_add_drive_to_hwgroup() and ide_remove_drive_from_hwgroup()
  (hwgroup->drive now only denotes the currently active device
   in the hwgroup).

* Update locking documentation in <linux/ide.h>.

While at it:

* Rename ->drive field in ide_hwgroup_t to ->cur_dev.

* Use __func__ in ide_timer_expiry().

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

2 files changed, 12 insertions, 90 deletions

diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index 1fc739f4415..4ce793c0562 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -742,12 +742,12 @@ repeat:
                          * set nIEN for previous port, drives in the
                          * quirk_list may not like intr setups/cleanups
                          */
-                        if (prev_port && hwgroup->drive->quirk_list == 0)
+                        if (prev_port && hwgroup->cur_dev->quirk_list == 0)
                                 prev_port->tp_ops->set_irq(prev_port, 0);
 
                         hwif->host->cur_port = hwif;
                 }
-                hwgroup->drive = drive;
+                hwgroup->cur_dev = drive;
                 drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED);
 
                 spin_unlock_irq(&hwgroup->lock);
@@ -913,9 +913,9 @@ void ide_timer_expiry (unsigned long data)
                  * Either way, we don't really want to complain about anything.
                  */
         } else {
-                drive = hwgroup->drive;
+                drive = hwgroup->cur_dev;
                 if (!drive) {
-                        printk(KERN_ERR "ide_timer_expiry: hwgroup->drive was NULL\n");
+                        printk(KERN_ERR "%s: ->cur_dev was NULL\n", __func__);
                         hwgroup->handler = NULL;
                 } else {
                         ide_hwif_t *hwif;
@@ -1033,7 +1033,7 @@ static void unexpected_intr(int irq, ide_hwif_t *hwif)
  *      places
  *
  *      hwif is the interface in the group currently performing
- *      a command. hwgroup->drive is the drive and hwgroup->handler is
+ *      a command. hwgroup->cur_dev is the drive and hwgroup->handler is
  *      the IRQ handler to call. As we issue a command the handlers
  *      step through multiple states, reassigning the handler to the
  *      next step in the process. Unlike a smart SCSI controller IDE
@@ -1105,7 +1105,7 @@ irqreturn_t ide_intr (int irq, void *dev_id)
                 goto out;
         }
 
-        drive = hwgroup->drive;
+        drive = hwgroup->cur_dev;
         if (!drive) {
                 /*
                  * This should NEVER happen, and there isn't much
diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 2752509531b..68f3c87b828 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -918,27 +918,9 @@ static int ide_init_queue(ide_drive_t *drive)
         return 0;
 }
 
-static void ide_add_drive_to_hwgroup(ide_drive_t *drive)
-{
-        ide_hwgroup_t *hwgroup = drive->hwif->hwgroup;
-
-        spin_lock_irq(&hwgroup->lock);
-        if (!hwgroup->drive) {
-                /* first drive for hwgroup. */
-                drive->next = drive;
-                hwgroup->drive = drive;
-                hwgroup->hwif = HWIF(hwgroup->drive);
-        } else {
-                drive->next = hwgroup->drive->next;
-                hwgroup->drive->next = drive;
-        }
-        spin_unlock_irq(&hwgroup->lock);
-}
-
 /*
  * For any present drive:
  * - allocate the block device queue
- * - link drive into the hwgroup
  */
 static int ide_port_setup_devices(ide_hwif_t *hwif)
 {
@@ -961,8 +943,6 @@ static int ide_port_setup_devices(ide_hwif_t *hwif)
                 }
 
                 j++;
-
-                ide_add_drive_to_hwgroup(drive);
         }
         mutex_unlock(&ide_cfg_mtx);
 
@@ -978,33 +958,9 @@ void ide_remove_port_from_hwgroup(ide_hwif_t *hwif)
         ide_ports[hwif->index] = NULL;
 
         spin_lock_irq(&hwgroup->lock);
-        /*
-         * Remove us from the hwgroup, and free
-         * the hwgroup if we were the only member
-         */
-        if (hwif->next == hwif) {
-                BUG_ON(hwgroup->hwif != hwif);
+        /* Free the hwgroup if we were the only member. */
+        if (--hwgroup->port_count == 0)
                 kfree(hwgroup);
-        } else {
-                /* There is another interface in hwgroup.
-                 * Unlink us, and set hwgroup->drive and ->hwif to
-                 * something sane.
-                 */
-                ide_hwif_t *g = hwgroup->hwif;
-
-                while (g->next != hwif)
-                        g = g->next;
-                g->next = hwif->next;
-                if (hwgroup->hwif == hwif) {
-                        /* Chose a random hwif for hwgroup->hwif.
-                         * It's guaranteed that there are no drives
-                         * left in the hwgroup.
-                         */
-                        BUG_ON(hwgroup->drive != NULL);
-                        hwgroup->hwif = g;
-                }
-                BUG_ON(hwgroup->hwif == hwif);
-        }
         spin_unlock_irq(&hwgroup->lock);
 }
 
@@ -1044,20 +1000,9 @@ static int init_irq (ide_hwif_t *hwif)
         if (match) {
                 hwgroup = match->hwgroup;
                 hwif->hwgroup = hwgroup;
-                /*
-                 * Link us into the hwgroup.
-                 * This must be done early, do ensure that unexpected_intr
-                 * can find the hwif and prevent irq storms.
-                 * No drives are attached to the new hwif, choose_drive
-                 * can't do anything stupid (yet).
-                 * Add ourself as the 2nd entry to the hwgroup->hwif
-                 * linked list, the first entry is the hwif that owns
-                 * hwgroup->handler - do not change that.
-                 */
+
                 spin_lock_irq(&hwgroup->lock);
-                hwif->next = hwgroup->hwif->next;
-                hwgroup->hwif->next = hwif;
-                BUG_ON(hwif->next == hwif);
+                hwgroup->port_count++;
                 spin_unlock_irq(&hwgroup->lock);
         } else {
                 hwgroup = kmalloc_node(sizeof(*hwgroup), GFP_KERNEL|__GFP_ZERO,
@@ -1068,7 +1013,8 @@ static int init_irq (ide_hwif_t *hwif)
                 spin_lock_init(&hwgroup->lock);
 
                 hwif->hwgroup = hwgroup;
-                hwgroup->hwif = hwif->next = hwif;
+
+                hwgroup->port_count = 1;
 
                 init_timer(&hwgroup->timer);
                 hwgroup->timer.function = &ide_timer_expiry;
@@ -1191,29 +1137,6 @@ void ide_init_disk(struct gendisk *disk, ide_drive_t *drive)
 
 EXPORT_SYMBOL_GPL(ide_init_disk);
 
-static void ide_remove_drive_from_hwgroup(ide_drive_t *drive)
-{
-        ide_hwgroup_t *hwgroup = drive->hwif->hwgroup;
-
-        if (drive == drive->next) {
-                /* special case: last drive from hwgroup. */
-                BUG_ON(hwgroup->drive != drive);
-                hwgroup->drive = NULL;
-        } else {
-                ide_drive_t *walk;
-
-                walk = hwgroup->drive;
-                while (walk->next != drive)
-                        walk = walk->next;
-                walk->next = drive->next;
-                if (hwgroup->drive == drive) {
-                        hwgroup->drive = drive->next;
-                        hwgroup->hwif = hwgroup->drive->hwif;
-                }
-        }
-        BUG_ON(hwgroup->drive == drive);
-}
-
 static void drive_release_dev (struct device *dev)
 {
         ide_drive_t *drive = container_of(dev, ide_drive_t, gendev);
@@ -1222,7 +1145,6 @@ static void drive_release_dev (struct device *dev)
         ide_proc_unregister_device(drive);
 
         spin_lock_irq(&hwgroup->lock);
-        ide_remove_drive_from_hwgroup(drive);
         kfree(drive->id);
         drive->id = NULL;
         drive->dev_flags &= ~IDE_DFLAG_PRESENT;