CAPI: Rework locking of controller data structures

This patch applies the mutex so far only protecting the controller list
to (almost) all accesses of controller data structures. It also reworks
waiting on state changes in old_capi_manufacturer so that it no longer
poll and holds a module reference to the controller owner while waiting
(the latter was partly done already). Modification and checking of the
blocked state remains racy by design, the caller is responsible for
dealing with this.
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/capi/kcapi.h

@@ -24,6 +24,7 @@ printk(KERN_DEBUG "%s: " format "\n" , __func__ , ## arg); \
 #endif
 
 enum {
+	CAPI_CTR_DETACHED = 0,
 	CAPI_CTR_DETECTED = 1,
 	CAPI_CTR_LOADING  = 2,
 	CAPI_CTR_RUNNING  = 3,
@@ -32,8 +33,10 @@ enum {
 extern struct list_head capi_drivers;
 extern struct mutex capi_drivers_lock;
 
-extern struct capi20_appl *capi_applications[CAPI_MAXAPPL];
 extern struct capi_ctr *capi_controller[CAPI_MAXCONTR];
+extern struct mutex capi_controller_lock;
+
+extern struct capi20_appl *capi_applications[CAPI_MAXAPPL];
 
 #ifdef CONFIG_PROC_FS
 

drivers/isdn/capi/kcapi_proc.c

@@ -35,7 +35,10 @@ static char *state2str(unsigned short state)
 // ---------------------------------------------------------------------------
 
 static void *controller_start(struct seq_file *seq, loff_t *pos)
+	__acquires(capi_controller_lock)
 {
+	mutex_lock(&capi_controller_lock);
+
 	if (*pos < CAPI_MAXCONTR)
 		return &capi_controller[*pos];
 
@@ -52,7 +55,9 @@ static void *controller_next(struct seq_file *seq, void *v, loff_t *pos)
 }
 
 static void controller_stop(struct seq_file *seq, void *v)
+	__releases(capi_controller_lock)
 {
+	mutex_unlock(&capi_controller_lock);
 }
 
 static int controller_show(struct seq_file *seq, void *v)

include/linux/isdn/capilli.h

@@ -66,9 +66,10 @@ struct capi_ctr {
 	unsigned long nsentdatapkt;
 
 	int cnr;				/* controller number */
-	volatile unsigned short state;		/* controller state */
-	volatile int blocked;			/* output blocked */
+	unsigned short state;			/* controller state */
+	int blocked;				/* output blocked */
 	int traceflag;				/* capi trace */
+	wait_queue_head_t state_wait_queue;
 
 	struct proc_dir_entry *procent;
         char procfn[128];