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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: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes 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: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bart Van Assche 2017-08-17 16:23:06 -07:00 committed by Jens Axboe
parent f846593391
commit 6d2cf6f2b4
2 changed files with 22 additions and 8 deletions
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15
block/genhd.c
View File

@ -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

15
block/partition-generic.c
View File

@ -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);