[PATCH 04/26] block: add a flag to make put_disk on partially initalized disks safer
From: Christoph Hellwig <hch@lst.de>
Date: 2021-05-21 05:51:54
Also in:
dm-devel, linux-bcache, linux-block, linux-m68k, linux-mmc, linux-raid, linux-s390, linuxppc-dev
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Add a flag to indicate that __device_add_disk did grab a queue reference so that disk_release only drops it if we actually had it. This sort out one of the major pitfals with partially initialized gendisk that a lot of drivers did get wrong or still do. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/genhd.c | 7 +++++-- include/linux/genhd.h | 1 + 2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index eec266c9318d..e4974af3d729 100644
--- a/block/genhd.c
+++ b/block/genhd.c@@ -541,7 +541,10 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk, * Take an extra ref on queue which will be put on disk_release() * so that it sticks around as long as @disk is there. */ - WARN_ON_ONCE(!blk_get_queue(disk->queue)); + if (blk_get_queue(disk->queue)) + set_bit(GD_QUEUE_REF, &disk->state); + else + WARN_ON_ONCE(1); disk_add_events(disk); blk_integrity_add(disk);
@@ -1116,7 +1119,7 @@ static void disk_release(struct device *dev) kfree(disk->random); xa_destroy(&disk->part_tbl); bdput(disk->part0); - if (disk->queue) + if (test_bit(GD_QUEUE_REF, &disk->state) && disk->queue) blk_put_queue(disk->queue); kfree(disk); }
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 7e9660ea967d..a5443f0b139d 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h@@ -153,6 +153,7 @@ struct gendisk { unsigned long state; #define GD_NEED_PART_SCAN 0 #define GD_READ_ONLY 1 +#define GD_QUEUE_REF 2 struct kobject *slave_dir; struct timer_rand_state *random;
--
2.30.2