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authorJeff Mahoney <jeffm@suse.com>2006-06-26 03:27:25 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 12:58:35 -0400
commit10da4f795f965f22039aa2930b6f80964aad3ee5 (patch)
tree6f4bfd27cdcdad15b53df997476fae539383bf4a
parent7ec75f254742766eb729f1d1024a5b4e6692fc5f (diff)
[PATCH] dm: add module ref counting
The reference counting on dm-mod is zero if no mapped devices are open. This is incorrect, and can lead to an oops if the module is unloaded while mapped devices exist. This patch claims a reference to the module whenever a device is created, and drops it again when the device is freed. Devices must be removed before dm-mod is unloaded. [akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled] Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/md/dm.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a5cc4c8462f3..29af584ae838 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -852,6 +852,9 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
852 return NULL; 852 return NULL;
853 } 853 }
854 854
855 if (!try_module_get(THIS_MODULE))
856 goto bad0;
857
855 /* get a minor number for the dev */ 858 /* get a minor number for the dev */
856 r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor); 859 r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
857 if (r < 0) 860 if (r < 0)
@@ -918,6 +921,8 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
918 blk_cleanup_queue(md->queue); 921 blk_cleanup_queue(md->queue);
919 free_minor(minor); 922 free_minor(minor);
920 bad1: 923 bad1:
924 module_put(THIS_MODULE);
925 bad0:
921 kfree(md); 926 kfree(md);
922 return NULL; 927 return NULL;
923} 928}
@@ -941,6 +946,7 @@ static void free_dev(struct mapped_device *md)
941 946
942 put_disk(md->disk); 947 put_disk(md->disk);
943 blk_cleanup_queue(md->queue); 948 blk_cleanup_queue(md->queue);
949 module_put(THIS_MODULE);
944 kfree(md); 950 kfree(md);
945} 951}
946 952