ide: add ide_device_{get,put}() helpers

* Add 'struct ide_host *host' field to ide_hwif_t and set it
  in ide_host_alloc_all().

* Add ide_device_{get,put}() helpers loosely based on SCSI's
  scsi_device_{get,put}() ones.

* Convert IDE device drivers to use ide_device_{get,put}().

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

7 files changed, 92 insertions, 13 deletions

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 4e73aeee4053..8f253e5f26a8 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -57,23 +57,29 @@ static DEFINE_MUTEX(idecd_ref_mutex);
 #define ide_cd_g(disk) \
         container_of((disk)->private_data, struct cdrom_info, driver)
 
+static void ide_cd_release(struct kref *);
+
 static struct cdrom_info *ide_cd_get(struct gendisk *disk)
 {
         struct cdrom_info *cd = NULL;
 
         mutex_lock(&idecd_ref_mutex);
         cd = ide_cd_g(disk);
-        if (cd)
+        if (cd) {
                 kref_get(&cd->kref);
+                if (ide_device_get(cd->drive)) {
+                        kref_put(&cd->kref, ide_cd_release);
+                        cd = NULL;
+                }
+        }
         mutex_unlock(&idecd_ref_mutex);
         return cd;
 }
 
-static void ide_cd_release(struct kref *);
-
 static void ide_cd_put(struct cdrom_info *cd)
 {
         mutex_lock(&idecd_ref_mutex);
+        ide_device_put(cd->drive);
         kref_put(&cd->kref, ide_cd_release);
         mutex_unlock(&idecd_ref_mutex);
 }
diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
index df5fe5756871..28d85b410f7c 100644
--- a/drivers/ide/ide-disk.c
+++ b/drivers/ide/ide-disk.c
@@ -56,23 +56,29 @@ static DEFINE_MUTEX(idedisk_ref_mutex);
 #define ide_disk_g(disk) \
         container_of((disk)->private_data, struct ide_disk_obj, driver)
 
+static void ide_disk_release(struct kref *);
+
 static struct ide_disk_obj *ide_disk_get(struct gendisk *disk)
 {
         struct ide_disk_obj *idkp = NULL;
 
         mutex_lock(&idedisk_ref_mutex);
         idkp = ide_disk_g(disk);
-        if (idkp)
+        if (idkp) {
                 kref_get(&idkp->kref);
+                if (ide_device_get(idkp->drive)) {
+                        kref_put(&idkp->kref, ide_disk_release);
+                        idkp = NULL;
+                }
+        }
         mutex_unlock(&idedisk_ref_mutex);
         return idkp;
 }
 
-static void ide_disk_release(struct kref *);
-
 static void ide_disk_put(struct ide_disk_obj *idkp)
 {
         mutex_lock(&idedisk_ref_mutex);
+        ide_device_put(idkp->drive);
         kref_put(&idkp->kref, ide_disk_release);
         mutex_unlock(&idedisk_ref_mutex);
 }
diff --git a/drivers/ide/ide-floppy.c b/drivers/ide/ide-floppy.c
index 3d8e6dd0f41e..ca11a26746f1 100644
--- a/drivers/ide/ide-floppy.c
+++ b/drivers/ide/ide-floppy.c
@@ -158,23 +158,29 @@ static DEFINE_MUTEX(idefloppy_ref_mutex);
 #define ide_floppy_g(disk) \
         container_of((disk)->private_data, struct ide_floppy_obj, driver)
 
+static void idefloppy_cleanup_obj(struct kref *);
+
 static struct ide_floppy_obj *ide_floppy_get(struct gendisk *disk)
 {
         struct ide_floppy_obj *floppy = NULL;
 
         mutex_lock(&idefloppy_ref_mutex);
         floppy = ide_floppy_g(disk);
-        if (floppy)
+        if (floppy) {
                 kref_get(&floppy->kref);
+                if (ide_device_get(floppy->drive)) {
+                        kref_put(&floppy->kref, idefloppy_cleanup_obj);
+                        floppy = NULL;
+                }
+        }
         mutex_unlock(&idefloppy_ref_mutex);
         return floppy;
 }
 
-static void idefloppy_cleanup_obj(struct kref *);
-
 static void ide_floppy_put(struct ide_floppy_obj *floppy)
 {
         mutex_lock(&idefloppy_ref_mutex);
+        ide_device_put(floppy->drive);
         kref_put(&floppy->kref, idefloppy_cleanup_obj);
         mutex_unlock(&idefloppy_ref_mutex);
 }
diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 890c15b1b3ae..9ab5892eaea1 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -1595,6 +1595,8 @@ struct ide_host *ide_host_alloc_all(const struct ide_port_info *d,
 
                 ide_init_port_data(hwif, idx);
 
+                hwif->host = host;
+
                 host->ports[i] = hwif;
                 host->n_ports++;
         }
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 6962ca4891a1..789f3428f072 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -322,23 +322,29 @@ static struct class *idetape_sysfs_class;
 #define ide_tape_g(disk) \
         container_of((disk)->private_data, struct ide_tape_obj, driver)
 
+static void ide_tape_release(struct kref *);
+
 static struct ide_tape_obj *ide_tape_get(struct gendisk *disk)
 {
         struct ide_tape_obj *tape = NULL;
 
         mutex_lock(&idetape_ref_mutex);
         tape = ide_tape_g(disk);
-        if (tape)
+        if (tape) {
                 kref_get(&tape->kref);
+                if (ide_device_get(tape->drive)) {
+                        kref_put(&tape->kref, ide_tape_release);
+                        tape = NULL;
+                }
+        }
         mutex_unlock(&idetape_ref_mutex);
         return tape;
 }
 
-static void ide_tape_release(struct kref *);
-
 static void ide_tape_put(struct ide_tape_obj *tape)
 {
         mutex_lock(&idetape_ref_mutex);
+        ide_device_put(tape->drive);
         kref_put(&tape->kref, ide_tape_release);
         mutex_unlock(&idetape_ref_mutex);
 }
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index 60f0ca66aa93..772451600e4d 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -618,6 +618,53 @@ set_val:
 
 EXPORT_SYMBOL(generic_ide_ioctl);
 
+/**
+ * ide_device_get       -       get an additional reference to a ide_drive_t
+ * @drive:      device to get a reference to
+ *
+ * Gets a reference to the ide_drive_t and increments the use count of the
+ * underlying LLDD module.
+ */
+int ide_device_get(ide_drive_t *drive)
+{
+        struct device *host_dev;
+        struct module *module;
+
+        if (!get_device(&drive->gendev))
+                return -ENXIO;
+
+        host_dev = drive->hwif->host->dev[0];
+        module = host_dev ? host_dev->driver->owner : NULL;
+
+        if (module && !try_module_get(module)) {
+                put_device(&drive->gendev);
+                return -ENXIO;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(ide_device_get);
+
+/**
+ * ide_device_put       -       release a reference to a ide_drive_t
+ * @drive:      device to release a reference on
+ *
+ * Release a reference to the ide_drive_t and decrements the use count of
+ * the underlying LLDD module.
+ */
+void ide_device_put(ide_drive_t *drive)
+{
+#ifdef CONFIG_MODULE_UNLOAD
+        struct device *host_dev = drive->hwif->host->dev[0];
+        struct module *module = host_dev ? host_dev->driver->owner : NULL;
+
+        if (module)
+                module_put(module);
+#endif
+        put_device(&drive->gendev);
+}
+EXPORT_SYMBOL_GPL(ide_device_put);
+
 static int ide_bus_match(struct device *dev, struct device_driver *drv)
 {
         return 1;
diff --git a/drivers/scsi/ide-scsi.c b/drivers/scsi/ide-scsi.c
index 538552495d48..318ef382448f 100644
--- a/drivers/scsi/ide-scsi.c
+++ b/drivers/scsi/ide-scsi.c
@@ -101,8 +101,13 @@ static struct ide_scsi_obj *ide_scsi_get(struct gendisk *disk)
 
         mutex_lock(&idescsi_ref_mutex);
         scsi = ide_scsi_g(disk);
-        if (scsi)
+        if (scsi) {
                 scsi_host_get(scsi->host);
+                if (ide_device_get(scsi->drive)) {
+                        scsi_host_put(scsi->host);
+                        scsi = NULL;
+                }
+        }
         mutex_unlock(&idescsi_ref_mutex);
         return scsi;
 }
@@ -110,6 +115,7 @@ static struct ide_scsi_obj *ide_scsi_get(struct gendisk *disk)
 static void ide_scsi_put(struct ide_scsi_obj *scsi)
 {
         mutex_lock(&idescsi_ref_mutex);
+        ide_device_put(scsi->drive);
         scsi_host_put(scsi->host);
         mutex_unlock(&idescsi_ref_mutex);
 }