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authorBart Van Assche <bart.vanassche@wdc.com>2017-08-17 16:23:06 -0700
committerJens Axboe <axboe@kernel.dk>2017-08-18 08:36:58 -0600
commit6d2cf6f2b446c4ace6f57402713ddbc09b11b0a9 (patch)
tree00de4770e862d2d130a8c1260400dbbd3a56230e /block
parentf846593391d86289bed6b4834a9717820561d571 (diff)
downloadlinux-0-day-6d2cf6f2b446c4ace6f57402713ddbc09b11b0a9.tar.gz
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>
Diffstat (limited to 'block')
-rw-r--r--block/genhd.c15
-rw-r--r--block/partition-generic.c15
2 files changed, 22 insertions, 8 deletions
diff --git a/block/genhd.c b/block/genhd.c
index 3dc4d11..2367087 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -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
diff --git a/block/partition-generic.c b/block/partition-generic.c
index fa5049a..1745a96 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -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);