Commit 6d2cf6f2 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

genhd: Annotate all part and part_tbl pointer dereferences 



Annotate gendisk.part_tbl and disk_part_tbl.part dereferences with
rcu_dereference_protected(). This patch does not change the behavior
of the modified code but ensures that sparse does not complain about
disk->part_tbl manipulations nor about part_tbl->part accesses.
Additionally, improve documentation of the locking requirements of
the modified functions.

Signed-off-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent f8465933

block/genhd.c

+10 −5
Original line number Diff line number Diff line
@@ -1127,12 +1127,13 @@ static const struct attribute_group *disk_attr_groups[] = { 
 * original ptbl is freed using RCU callback.

 *

 * LOCKING:

 * Matching bd_mutx locked.

 * Matching bd_mutex locked or the caller is the only user of @disk.

 */

static void disk_replace_part_tbl(struct gendisk *disk,

				  struct disk_part_tbl *new_ptbl)

{

	struct disk_part_tbl *old_ptbl = disk->part_tbl;

	struct disk_part_tbl *old_ptbl =

		rcu_dereference_protected(disk->part_tbl, 1);



	rcu_assign_pointer(disk->part_tbl, new_ptbl);
@@ -1151,14 +1152,16 @@ static void disk_replace_part_tbl(struct gendisk *disk, 
 * uses RCU to allow unlocked dereferencing for stats and other stuff.

 *

 * LOCKING:

 * Matching bd_mutex locked, might sleep.

 * Matching bd_mutex locked or the caller is the only user of @disk.

 * Might sleep.

 *

 * RETURNS:

 * 0 on success, -errno on failure.

 */

int disk_expand_part_tbl(struct gendisk *disk, int partno)

{

	struct disk_part_tbl *old_ptbl = disk->part_tbl;

	struct disk_part_tbl *old_ptbl =

		rcu_dereference_protected(disk->part_tbl, 1);

	struct disk_part_tbl *new_ptbl;

	int len = old_ptbl ? old_ptbl->len : 0;

	int i, target;
@@ -1352,6 +1355,7 @@ EXPORT_SYMBOL(alloc_disk); 
struct gendisk *alloc_disk_node(int minors, int node_id)

{

	struct gendisk *disk;

	struct disk_part_tbl *ptbl;



	disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);

	if (disk) {
@@ -1365,7 +1369,8 @@ struct gendisk *alloc_disk_node(int minors, int node_id) 
			kfree(disk);

			return NULL;

		}

		disk->part_tbl->part[0] = &disk->part0;

		ptbl = rcu_dereference_protected(disk->part_tbl, 1);

		rcu_assign_pointer(ptbl->part[0], &disk->part0);



		/*

		 * set_capacity() and get_capacity() currently don't use

block/partition-generic.c

+12 −3
Original line number Diff line number Diff line
@@ -252,15 +252,20 @@ void __delete_partition(struct percpu_ref *ref) 
	call_rcu(&part->rcu_head, delete_partition_rcu_cb);

}



/*

 * Must be called either with bd_mutex held, before a disk can be opened or

 * after all disk users are gone.

 */

void delete_partition(struct gendisk *disk, int partno)

{

	struct disk_part_tbl *ptbl = disk->part_tbl;

	struct disk_part_tbl *ptbl =

		rcu_dereference_protected(disk->part_tbl, 1);

	struct hd_struct *part;



	if (partno >= ptbl->len)

		return;



	part = ptbl->part[partno];

	part = rcu_dereference_protected(ptbl->part[partno], 1);

	if (!part)

		return;
@@ -280,6 +285,10 @@ static ssize_t whole_disk_show(struct device *dev, 
static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH,

		   whole_disk_show, NULL);



/*

 * Must be called either with bd_mutex held, before a disk can be opened or

 * after all disk users are gone.

 */

struct hd_struct *add_partition(struct gendisk *disk, int partno,

				sector_t start, sector_t len, int flags,

				struct partition_meta_info *info)
@@ -295,7 +304,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno, 
	err = disk_expand_part_tbl(disk, partno);

	if (err)

		return ERR_PTR(err);

	ptbl = disk->part_tbl;

	ptbl = rcu_dereference_protected(disk->part_tbl, 1);



	if (ptbl->part[partno])

		return ERR_PTR(-EBUSY);

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