From 6d2cf6f2b446c4ace6f57402713ddbc09b11b0a9 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 17 Aug 2017 16:23:06 -0700 Subject: 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 Reviewed-by: Hannes Reinecke Cc: Tejun Heo Cc: Jan Kara Cc: Dan Williams Cc: Christoph Hellwig Signed-off-by: Jens Axboe --- block/genhd.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 3dc4d115480f..2367087cdb7c 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 -- cgit v1.2.3