lapd_core: Ensure we always have some tailroom
At some points, e.g. when allocating message buffers from the Tx
history, we used to allocate them exactly as large as the defined
headroom plus the user data. This means that the underlying PH layer
(E1 mostly) had no tailroom to add anything to the end of the message.
Especially for DAHDI this is a problem, as we need to make space for
two more bytes of frame check sequence (FCS).
So let's simply make sure we always have some extra space at the end
of such buffers.
Change-Id: Id362ce131157c7513d744b0248c7f78fb75c590c
Related: OS#4644
diff --git a/src/gsm/lapd_core.c b/src/gsm/lapd_core.c
index c77b663..cf25f3d 100644
--- a/src/gsm/lapd_core.c
+++ b/src/gsm/lapd_core.c
@@ -104,6 +104,7 @@
#define CR_NET2USER_RESP 0
#define LAPD_HEADROOM 56
+#define LAPD_TAILROOM 16
#define SBIT(a) (1 << a)
#define ALL_STATES 0xffffffff
@@ -120,7 +121,7 @@
/* adding space for padding, FIXME: add as an option */
if (length < 21)
length = 21;
- return msgb_alloc_headroom(length + LAPD_HEADROOM, LAPD_HEADROOM, name);
+ return msgb_alloc_headroom(length + LAPD_HEADROOM + LAPD_TAILROOM, LAPD_HEADROOM, name);
}
static inline uint8_t do_mod(uint8_t x, uint8_t m)