dahdi_dynamic: Do not call into dahdi_dynamic without holding reference.

Instead of registering a function pointer, register a dahdi_dynamic_ops
structure that contains the owner as well as the ioctl callback. This way
dahdi.ko can bump up the reference count on dahdi_dynamic.ko before calling
the ioctl callback.

Also, use the registration mutex to guard against the module being unloaded
between the time the structure pointer was checked, and the module reference
is taken.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@10623 a0bf4364-ded3-4de4-8d8a-66a801d63aff

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/dahdi/dahdi_dynamic.c b/drivers/dahdi/dahdi_dynamic.c
index 79c8bba..602ebe9 100644
--- a/drivers/dahdi/dahdi_dynamic.c
+++ b/drivers/dahdi/dahdi_dynamic.c
@@ -818,10 +818,13 @@ static void check_for_red_alarm(unsigned long ignored)
 	mod_timer(&alarmcheck, jiffies + 1 * HZ);
 }
 
+static const struct dahdi_dynamic_ops dahdi_dynamic_ops = {
+	.owner = THIS_MODULE,
+	.ioctl = dahdi_dynamic_ioctl,
+};
+
 static int dahdi_dynamic_init(void)
 {
-	dahdi_set_dynamic_ioctl(dahdi_dynamic_ioctl);
-
 	/* Start process to check for RED ALARM */
 	init_timer(&alarmcheck);
 	alarmcheck.expires = 0;
@@ -832,19 +835,22 @@ static int dahdi_dynamic_init(void)
 #ifdef ENABLE_TASKLETS
 	tasklet_init(&dahdi_dynamic_tlet, dahdi_dynamic_tasklet, 0);
 #endif
+	dahdi_set_dynamic_ops(&dahdi_dynamic_ops);
+
 	printk(KERN_INFO "DAHDI Dynamic Span support LOADED\n");
 	return 0;
 }
 
 static void dahdi_dynamic_cleanup(void)
 {
+	dahdi_set_dynamic_ops(NULL);
+
 #ifdef ENABLE_TASKLETS
 	if (taskletpending) {
 		tasklet_disable(&dahdi_dynamic_tlet);
 		tasklet_kill(&dahdi_dynamic_tlet);
 	}
 #endif
-	dahdi_set_dynamic_ioctl(NULL);
 	del_timer(&alarmcheck);
 	printk(KERN_INFO "DAHDI Dynamic Span support unloaded\n");
 }