From a288cafeceb6e18ba4fd10ec8d3270593472cca6 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Tue, 26 Aug 2014 09:05:36 -0600 Subject: block: Fix dev_t minor allocation lifetime commit 2da78092dda13f1efd26edbbf99a567776913750 upstream. Releases the dev_t minor when all references are closed to prevent another device from acquiring the same major/minor. Since the partition's release may be invoked from call_rcu's soft-irq context, the ext_dev_idr's mutex had to be replaced with a spinlock so as not so sleep. Signed-off-by: Keith Busch Signed-off-by: Jens Axboe [bwh: Backported to 3.2: - Adjust filename - idr insertion API is different, and blk_alloc_devt() is preallocating a node in a different way] Signed-off-by: Ben Hutchings --- block/genhd.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'block') diff --git a/block/genhd.c b/block/genhd.c index 8bd4ef2..35415810 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -28,10 +28,10 @@ struct kobject *block_depr; /* for extended dynamic devt allocation, currently only one major is used */ #define NR_EXT_DEVT (1 << MINORBITS) -/* For extended devt allocation. ext_devt_mutex prevents look up +/* For extended devt allocation. ext_devt_lock prevents look up * results from going away underneath its user. */ -static DEFINE_MUTEX(ext_devt_mutex); +static DEFINE_SPINLOCK(ext_devt_lock); static DEFINE_IDR(ext_devt_idr); static struct device_type disk_type; @@ -421,13 +421,13 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt) do { if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL)) return -ENOMEM; - mutex_lock(&ext_devt_mutex); + spin_lock(&ext_devt_lock); rc = idr_get_new(&ext_devt_idr, part, &idx); if (!rc && idx >= NR_EXT_DEVT) { idr_remove(&ext_devt_idr, idx); rc = -EBUSY; } - mutex_unlock(&ext_devt_mutex); + spin_unlock(&ext_devt_lock); } while (rc == -EAGAIN); if (rc) @@ -454,9 +454,9 @@ void blk_free_devt(dev_t devt) return; if (MAJOR(devt) == BLOCK_EXT_MAJOR) { - mutex_lock(&ext_devt_mutex); + spin_lock(&ext_devt_lock); idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt))); - mutex_unlock(&ext_devt_mutex); + spin_unlock(&ext_devt_lock); } } @@ -663,7 +663,6 @@ void del_gendisk(struct gendisk *disk) if (!sysfs_deprecated) sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk))); device_del(disk_to_dev(disk)); - blk_free_devt(disk_to_dev(disk)->devt); } EXPORT_SYMBOL(del_gendisk); @@ -688,13 +687,13 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) } else { struct hd_struct *part; - mutex_lock(&ext_devt_mutex); + spin_lock(&ext_devt_lock); part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt))); if (part && get_disk(part_to_disk(part))) { *partno = part->partno; disk = part_to_disk(part); } - mutex_unlock(&ext_devt_mutex); + spin_unlock(&ext_devt_lock); } return disk; @@ -1102,6 +1101,7 @@ static void disk_release(struct device *dev) { struct gendisk *disk = dev_to_disk(dev); + blk_free_devt(dev->devt); disk_release_events(disk); kfree(disk->random); disk_replace_part_tbl(disk, NULL); -- cgit v1.1