From 10da4f795f965f22039aa2930b6f80964aad3ee5 Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Mon, 26 Jun 2006 00:27:25 -0700 Subject: [PATCH] [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 Signed-off-by: Alasdair G Kergon Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/dm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index a5cc4c8462..29af584ae8 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) return NULL; } + if (!try_module_get(THIS_MODULE)) + goto bad0; + /* get a minor number for the dev */ r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor); if (r < 0) @@ -918,6 +921,8 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent) blk_cleanup_queue(md->queue); free_minor(minor); bad1: + module_put(THIS_MODULE); + bad0: kfree(md); return NULL; } @@ -941,6 +946,7 @@ static void free_dev(struct mapped_device *md) put_disk(md->disk); blk_cleanup_queue(md->queue); + module_put(THIS_MODULE); kfree(md); } -- 2.39.5