mISDN: Reduce RX buffer allocation for transparent data
We did allways allocate maxsize buffers, but for transparent data we know
the actual size.
Use a common function to calculate size and detect overflows.
Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/mISDN/hwchannel.c b/drivers/isdn/mISDN/hwchannel.c
index 5c5ab47..3c2145d 100644
--- a/drivers/isdn/mISDN/hwchannel.c
+++ b/drivers/isdn/mISDN/hwchannel.c
@@ -201,20 +201,30 @@
{
struct mISDNhead *hh;
- hh = mISDN_HEAD_P(bch->rx_skb);
- hh->prim = PH_DATA_IND;
- hh->id = id;
- if (bch->rcount >= 64) {
- printk(KERN_WARNING "B-channel %p receive queue overflow, "
- "flushing!\n", bch);
- skb_queue_purge(&bch->rqueue);
- bch->rcount = 0;
+ /* if allocation did fail upper functions still may call us */
+ if (unlikely(!bch->rx_skb))
return;
+ if (unlikely(!bch->rx_skb->len)) {
+ /* we have no data to send - this may happen after recovery
+ * from overflow or too small allocation.
+ * We need to free the buffer here */
+ dev_kfree_skb(bch->rx_skb);
+ bch->rx_skb = NULL;
+ } else {
+ hh = mISDN_HEAD_P(bch->rx_skb);
+ hh->prim = PH_DATA_IND;
+ hh->id = id;
+ if (bch->rcount >= 64) {
+ printk(KERN_WARNING
+ "B%d receive queue overflow - flushing!\n",
+ bch->nr);
+ skb_queue_purge(&bch->rqueue);
+ }
+ bch->rcount++;
+ skb_queue_tail(&bch->rqueue, bch->rx_skb);
+ bch->rx_skb = NULL;
+ schedule_event(bch, FLG_RECVQUEUE);
}
- bch->rcount++;
- skb_queue_tail(&bch->rqueue, bch->rx_skb);
- bch->rx_skb = NULL;
- schedule_event(bch, FLG_RECVQUEUE);
}
EXPORT_SYMBOL(recv_Bchannel);
@@ -399,3 +409,44 @@
}
}
EXPORT_SYMBOL(bchannel_senddata);
+
+/* The function allocates a new receive skb on demand with a size for the
+ * requirements of the current protocol. It returns the tailroom of the
+ * receive skb or an error.
+ */
+int
+bchannel_get_rxbuf(struct bchannel *bch, int reqlen)
+{
+ int len;
+
+ if (bch->rx_skb) {
+ len = skb_tailroom(bch->rx_skb);
+ if (len < reqlen) {
+ pr_warning("B%d no space for %d (only %d) bytes\n",
+ bch->nr, reqlen, len);
+ if (test_bit(FLG_TRANSPARENT, &bch->Flags)) {
+ /* send what we have now and try a new buffer */
+ recv_Bchannel(bch, 0);
+ } else {
+ /* on HDLC we have to drop too big frames */
+ return -EMSGSIZE;
+ }
+ } else {
+ return len;
+ }
+ }
+ if (unlikely(reqlen > bch->maxlen))
+ return -EMSGSIZE;
+ if (test_bit(FLG_TRANSPARENT, &bch->Flags))
+ len = reqlen;
+ else /* with HDLC we do not know the length yet */
+ len = bch->maxlen;
+ bch->rx_skb = mI_alloc_skb(len, GFP_ATOMIC);
+ if (!bch->rx_skb) {
+ pr_warning("B%d receive no memory for %d bytes\n",
+ bch->nr, len);
+ len = -ENOMEM;
+ }
+ return len;
+}
+EXPORT_SYMBOL(bchannel_get_rxbuf);