From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 27 Aug 2012 23:56:53 +0000 (-0300)
Subject: genhd: Make put_disk() safe for disks that have not been registered
X-Git-Tag: next-20120910~57^2~1^2^2~4
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b33d002f4b6bae912463e5a66387c498aa69b6fe;p=karo-tx-linux.git

genhd: Make put_disk() safe for disks that have not been registered

Since commit 523e1d3 ('block: make gendisk hold a reference to its
queue'), add_disk() adds a reference to disk->queue, which is then
dropped by disk_release().  But if a disk is destroyed without being
registered through add_disk() (or if add_disk() fails at the first
hurdle) then we have a reference imbalance.

Use the GENHD_FL_UP flag to tell whether this extra reference has been
added.  Remove the incomplete workaround from the floppy driver.

Cc: stable@vger.kernel.org
Acked-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---

diff --git a/block/genhd.c b/block/genhd.c
index d839723303c8..633751dbb9a9 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -587,8 +587,6 @@ void add_disk(struct gendisk *disk)
 	WARN_ON(disk->minors && !(disk->major || disk->first_minor));
 	WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
 
-	disk->flags |= GENHD_FL_UP;
-
 	retval = blk_alloc_devt(&disk->part0, &devt);
 	if (retval) {
 		WARN_ON(1);
@@ -596,6 +594,8 @@ void add_disk(struct gendisk *disk)
 	}
 	disk_to_dev(disk)->devt = devt;
 
+	disk->flags |= GENHD_FL_UP;
+
 	/* ->major and ->first_minor aren't supposed to be
 	 * dereferenced from here on, but set them just in case.
 	 */
@@ -1105,7 +1105,7 @@ static void disk_release(struct device *dev)
 	disk_replace_part_tbl(disk, NULL);
 	free_part_stats(&disk->part0);
 	free_part_info(&disk->part0);
-	if (disk->queue)
+	if (disk->queue && disk->flags & GENHD_FL_UP)
 		blk_put_queue(disk->queue);
 	kfree(disk);
 }
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 1e09e998904f..32551f254054 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4322,14 +4322,8 @@ out_unreg_blkdev:
 out_put_disk:
 	while (dr--) {
 		del_timer_sync(&motor_off_timer[dr]);
-		if (disks[dr]->queue) {
+		if (disks[dr]->queue)
 			blk_cleanup_queue(disks[dr]->queue);
-			/*
-			 * put_disk() is not paired with add_disk() and
-			 * will put queue reference one extra time. fix it.
-			 */
-			disks[dr]->queue = NULL;
-		}
 		put_disk(disks[dr]);
 	}
 	destroy_workqueue(floppy_wq);
@@ -4558,14 +4552,6 @@ static void __exit floppy_module_exit(void)
 		}
 		blk_cleanup_queue(disks[drive]->queue);
 
-		/*
-		 * These disks have not called add_disk().  Don't put down
-		 * queue reference in put_disk().
-		 */
-		if (!(allowed_drive_mask & (1 << drive)) ||
-		    fdc_state[FDC(drive)].version == FDC_NONE)
-			disks[drive]->queue = NULL;
-
 		put_disk(disks[drive]);
 	}