[PATCH master 3/3] partition: reparse tables only if CONFIG_PARTITION_MANIPULATION=y

[Ahmad Fatoum]

reparse_partition_table() will delete a device's existing partition
cdevs and allocate new ones according to the new partition table.

Holding a reference to a cdev prevents it from bring removed to avoid
dangling pointers and use-after-frees.

Unfortunately, not all users call cdev_open on the cdev and increment
the usage count, instead using functions like cdev_by_name, which don't
call cdev_open.

The proper solution for this is probably to change all functions that
return a cdev to actually take a reference to the cdev.

This will involve quite a bit of work though, so for now, restore old
behavior by making reparsing of the partition tables dependent on
CONFIG_PARTITION_MANIPULATION=y.

The option isn't fully appropriate as partition manipulation can happen
by writing to the parent block device, but not noticing changes of
partitions is the behavior we had before.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 common/partitions.c |  2 ++
 include/disks.h     | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/common/partitions.c b/common/partitions.c
index 17c2f1eb281a..0b10377e7327 100644
--- a/common/partitions.c
+++ b/common/partitions.c
@@ -266,6 +266,7 @@ int parse_partition_table(struct block_device *blk)
 	return rc;
 }
 
+#ifdef CONFIG_PARTITION_MANIPULATION
 int reparse_partition_table(struct block_device *blk)
 {
 	struct cdev *cdev = &blk->cdev;
@@ -285,6 +286,7 @@ int reparse_partition_table(struct block_device *blk)
 
 	return parse_partition_table(blk);
 }
+#endif
 
 int partition_parser_register(struct partition_parser *p)
 {
diff --git a/include/disks.h b/include/disks.h
index ccb50d3ce94f..a3673d1e276f 100644
--- a/include/disks.h
+++ b/include/disks.h
@@ -3,6 +3,9 @@
 #ifndef DISKS_H
 #define DISKS_H
 
+#include <linux/types.h>
+#include <linux/errno.h>
+
 struct block_device;
 
 /** Size of one sector in bytes */
@@ -24,6 +27,14 @@ struct partition_entry {
 } __attribute__ ((packed));
 
 extern int parse_partition_table(struct block_device*);
+
+#ifdef CONFIG_PARTITION_MANIPULATION
 int reparse_partition_table(struct block_device *blk);
+#else
+static inline int reparse_partition_table(struct block_device *blk)
+{
+	return -ENOSYS;
+}
+#endif
 
 #endif /* DISKS_H */
-- 
2.39.2