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genhd: Annotate all part and part_tbl pointer dereferences

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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 <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Bart Van Assche 2017-08-17 16:23:06 -07:00 • committed by Jens Axboe
commit 6d2cf6f2b4
2 changed files with 22 additions and 8 deletions
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15
block/partition-generic.c
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@ -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);