[PATCH 2/7] isdn/capi: make reset_ctr op truly optional

[Tilman Schmidt <tilman-ZTO5kqT2PaM@public.gmane.org>]

The CAPI controller operation reset_ctr is marked as optional, and
not all drivers do implement it. Add a check to the kernel CAPI
whether it exists before trying to call it.

Impact: oops prevention
Signed-off-by: Tilman Schmidt <tilman-ZTO5kqT2PaM@public.gmane.org>
---
 drivers/isdn/capi/kcapi.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/isdn/capi/kcapi.c b/drivers/isdn/capi/kcapi.c
index bd00dce..bde3c88 100644
--- a/drivers/isdn/capi/kcapi.c
+++ b/drivers/isdn/capi/kcapi.c
@@ -1147,6 +1147,12 @@ load_unlock_out:
 		if (ctr->state == CAPI_CTR_DETECTED)
 			goto reset_unlock_out;
 
+		if (ctr->reset_ctr == NULL) {
+			printk(KERN_DEBUG "kcapi: reset: no reset function\n");
+			retval = -ESRCH;
+			goto reset_unlock_out;
+		}
+
 		ctr->reset_ctr(ctr);
 
 		retval = wait_on_ctr_state(ctr, CAPI_CTR_DETECTED);
-- 
1.6.5.3.298.g39add