CAPI: Silence lockdep warning on get_capi_appl_by_nr usage

As long as we hold capi_controller_lock, we can safely access
capi_applications without RCU protection as no one can modify the
application list underneath us. Introduce an RCU-free
__get_capi_appl_by_nr for this purpose. This silences lockdep warnings
on suspicious rcu_dereference usage.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/isdn/capi/kcapi.c b/drivers/isdn/capi/kcapi.c
index b054494df846..3acf94cc5acd 100644
--- a/drivers/isdn/capi/kcapi.c
+++ b/drivers/isdn/capi/kcapi.c
@@ -98,6 +98,16 @@ static inline struct capi_ctr *get_capi_ctr_by_nr(u16 contr)
         return capi_controller[contr - 1];
 }
 
+static inline struct capi20_appl *__get_capi_appl_by_nr(u16 applid)
+{
+        lockdep_assert_held(&capi_controller_lock);
+
+        if (applid - 1 >= CAPI_MAXAPPL)
+                return NULL;
+
+        return capi_applications[applid - 1];
+}
+
 static inline struct capi20_appl *get_capi_appl_by_nr(u16 applid)
 {
         if (applid - 1 >= CAPI_MAXAPPL)
@@ -185,10 +195,9 @@ static void notify_up(u32 contr)
                 ctr->state = CAPI_CTR_RUNNING;
 
                 for (applid = 1; applid <= CAPI_MAXAPPL; applid++) {
-                        ap = get_capi_appl_by_nr(applid);
-                        if (!ap)
-                                continue;
-                        register_appl(ctr, applid, &ap->rparam);
+                        ap = __get_capi_appl_by_nr(applid);
+                        if (ap)
+                                register_appl(ctr, applid, &ap->rparam);
                 }
 
                 wake_up_interruptible_all(&ctr->state_wait_queue);
@@ -215,7 +224,7 @@ static void ctr_down(struct capi_ctr *ctr, int new_state)
         memset(ctr->serial, 0, sizeof(ctr->serial));
 
         for (applid = 1; applid <= CAPI_MAXAPPL; applid++) {
-                ap = get_capi_appl_by_nr(applid);
+                ap = __get_capi_appl_by_nr(applid);
                 if (ap)
                         capi_ctr_put(ctr);
         }