CAPI: Convert capidev_list_lock into a mutex

No need for anything "harder" here (specifically no need for
irqsave...). Also, make the list removal the first operation of
capidev_free to avoid dumping half-released devices via /proc.
Signed-off-by: NJan Kiszka <jan.kiszka@web.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/capi/capi.c

@@ -146,7 +146,7 @@ struct capidev {
 
 /* -------- global variables ---------------------------------------- */
 
-static DEFINE_RWLOCK(capidev_list_lock);
+static DEFINE_MUTEX(capidev_list_lock);
 static LIST_HEAD(capidev_list);
 
 #ifdef CONFIG_ISDN_CAPI_MIDDLEWARE
@@ -406,7 +406,6 @@ static struct capincci *capincci_find(struct capidev *cdev, u32 ncci)
 static struct capidev *capidev_alloc(void)
 {
 	struct capidev *cdev;
-	unsigned long flags;
 
 	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
 	if (!cdev)
@@ -415,15 +414,19 @@ static struct capidev *capidev_alloc(void)
 	mutex_init(&cdev->ncci_list_mtx);
 	skb_queue_head_init(&cdev->recvqueue);
 	init_waitqueue_head(&cdev->recvwait);
-	write_lock_irqsave(&capidev_list_lock, flags);
+
+	mutex_lock(&capidev_list_lock);
 	list_add_tail(&cdev->list, &capidev_list);
-	write_unlock_irqrestore(&capidev_list_lock, flags);
+	mutex_unlock(&capidev_list_lock);
+
         return cdev;
 }
 
 static void capidev_free(struct capidev *cdev)
 {
-	unsigned long flags;
+	mutex_lock(&capidev_list_lock);
+	list_del(&cdev->list);
+	mutex_unlock(&capidev_list_lock);
 
 	if (cdev->ap.applid) {
 		capi20_release(&cdev->ap);
@@ -435,9 +438,6 @@ static void capidev_free(struct capidev *cdev)
 	capincci_free(cdev, 0xffffffff);
 	mutex_unlock(&cdev->ncci_list_mtx);
 
-	write_lock_irqsave(&capidev_list_lock, flags);
-	list_del(&cdev->list);
-	write_unlock_irqrestore(&capidev_list_lock, flags);
 	kfree(cdev);
 }
 
@@ -1431,7 +1431,7 @@ static int capi20_proc_show(struct seq_file *m, void *v)
         struct capidev *cdev;
 	struct list_head *l;
 
-	read_lock(&capidev_list_lock);
+	mutex_lock(&capidev_list_lock);
 	list_for_each(l, &capidev_list) {
 		cdev = list_entry(l, struct capidev, list);
 		seq_printf(m, "0 %d %lu %lu %lu %lu\n",
@@ -1441,7 +1441,7 @@ static int capi20_proc_show(struct seq_file *m, void *v)
 			cdev->ap.nsentctlpkt,
 			cdev->ap.nsentdatapkt);
 	}
-	read_unlock(&capidev_list_lock);
+	mutex_unlock(&capidev_list_lock);
 	return 0;
 }
 
@@ -1468,7 +1468,7 @@ static int capi20ncci_proc_show(struct seq_file *m, void *v)
         struct capincci *np;
 	struct list_head *l;
 
-	read_lock(&capidev_list_lock);
+	mutex_lock(&capidev_list_lock);
 	list_for_each(l, &capidev_list) {
 		cdev = list_entry(l, struct capidev, list);
 		for (np=cdev->nccis; np; np = np->next) {
@@ -1477,7 +1477,7 @@ static int capi20ncci_proc_show(struct seq_file *m, void *v)
 				       np->ncci);
 		}
 	}
-	read_unlock(&capidev_list_lock);
+	mutex_unlock(&capidev_list_lock);
 	return 0;
 }