isdn/gigaset: honor CAPI application's buffer size request

Fix the Gigaset CAPI driver to limit the length of a connection's
payload data receive buffers to the corresponding CAPI application's
data buffer size, as some real-life CAPI applications tend to be
rather unhappy if they receive bigger data blocks than requested.

Impact: bugfix
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 8 deletions

diff --git a/drivers/isdn/gigaset/gigaset.h b/drivers/isdn/gigaset/gigaset.h
index 05947f9c1849..f77ec54eb07d 100644
--- a/drivers/isdn/gigaset/gigaset.h
+++ b/drivers/isdn/gigaset/gigaset.h
@@ -45,10 +45,6 @@
 #define MAX_EVENTS 64           /* size of event queue */
 
 #define RBUFSIZE 8192
-#define SBUFSIZE 4096           /* sk_buff payload size */
-
-#define TRANSBUFSIZE 768        /* bytes per skb for transparent receive */
-#define MAX_BUF_SIZE (SBUFSIZE - 2)     /* Max. size of a data packet from LL */
 
 /* compile time options */
 #define GIG_MAJOR 0
@@ -380,8 +376,10 @@ struct bc_state {
 
         struct at_state_t at_state;
 
-        __u16 fcs;
-        struct sk_buff *skb;
+        /* receive buffer */
+        unsigned rx_bufsize;            /* max size accepted by application */
+        struct sk_buff *rx_skb;
+        __u16 rx_fcs;
         int inputstate;                 /* see INS_XXXX */
 
         int channel;
@@ -801,8 +799,23 @@ static inline void gigaset_bchannel_up(struct bc_state *bcs)
         gigaset_schedule_event(bcs->cs);
 }
 
-/* handling routines for sk_buff */
-/* ============================= */
+/* set up next receive skb for data mode */
+static inline struct sk_buff *gigaset_new_rx_skb(struct bc_state *bcs)
+{
+        struct cardstate *cs = bcs->cs;
+        unsigned short hw_hdr_len = cs->hw_hdr_len;
+
+        if (bcs->ignore) {
+                bcs->rx_skb = NULL;
+        } else {
+                bcs->rx_skb = dev_alloc_skb(bcs->rx_bufsize + hw_hdr_len);
+                if (bcs->rx_skb == NULL)
+                        dev_warn(cs->dev, "could not allocate skb\n");
+                else
+                        skb_reserve(bcs->rx_skb, hw_hdr_len);
+        }
+        return bcs->rx_skb;
+}
 
 /* append received bytes to inbuf */
 int gigaset_fill_inbuf(struct inbuf_t *inbuf, const unsigned char *src,