dahdi: Prevent unloadable module on failed open.

If chan->span->ops->open() fails then the reference count of the module
implementing the board driver will not be decremented.  The result is a
module that would always be "in use" and unloadable.

This change makes sure to release that reference when open failed.

(closes issue #18422)
Reported by: avarvit

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Acked-by: Angelos Varvitsiotis <avarvit@admin.grnet.gr>

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@9510 a0bf4364-ded3-4de4-8d8a-66a801d63aff

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/dahdi/dahdi-base.c b/drivers/dahdi/dahdi-base.c
index 60a070e..a292619 100644
--- a/drivers/dahdi/dahdi-base.c
+++ b/drivers/dahdi/dahdi-base.c
@@ -2756,6 +2756,7 @@ static int dahdi_specchan_open(struct file *file)
 			res = -EBUSY;
 		else if (!test_and_set_bit(DAHDI_FLAGBIT_OPEN, &chan->flags)) {
 			unsigned long flags;
+			const struct dahdi_span_ops *ops;
 			res = initialize_channel(chan);
 			if (res) {
 				/* Reallocbufs must have failed */
@@ -2763,13 +2764,17 @@ static int dahdi_specchan_open(struct file *file)
 				return res;
 			}
 			spin_lock_irqsave(&chan->lock, flags);
+			ops = chan->span->ops;
 			if (is_pseudo_chan(chan))
 				chan->flags |= DAHDI_FLAG_AUDIO;
 			if (chan->span) {
-				if (!try_module_get(chan->span->ops->owner))
+				if (!try_module_get(ops->owner)) {
 					res = -ENXIO;
-				else if (chan->span->ops->open)
-					res = chan->span->ops->open(chan);
+				} else if (ops->open) {
+					res = ops->open(chan);
+					if (res)
+						module_put(ops->owner);
+				}
 			}
 			if (!res) {
 				chan->file = file;