smc: remote memory buffers (RMBs)

* allocate data RMB memory for sending and receiving
* size depends on the maximum socket send and receive buffers
* allocated RMBs are kept during life time of the owning link group
* map the allocated RMBs to DMA

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 45 insertions, 0 deletions

diff --git a/net/smc/smc.h b/net/smc/smc.h
index 11265bde4655..2bf504492133 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -34,6 +34,16 @@ struct smc_connection {
 	struct smc_link_group	*lgr;		/* link group of connection */
 	u32			alert_token_local; /* unique conn. id */
 	u8			peer_conn_idx;	/* from tcp handshake */
+	int			peer_rmbe_size;	/* size of peer rx buffer */
+	atomic_t		peer_rmbe_space;/* remaining free bytes in peer
+						 * rmbe
+						 */
+
+	struct smc_buf_desc	*sndbuf_desc;	/* send buffer descriptor */
+	int			sndbuf_size;	/* sndbuf size <== sock wmem */
+	struct smc_buf_desc	*rmb_desc;	/* RMBE descriptor */
+	int			rmbe_size;	/* RMBE size <== sock rmem */
+	int			rmbe_size_short;/* compressed notation */
 };
 
 struct smc_sock {				/* smc sock container */
@@ -76,6 +86,41 @@ static inline u32 ntoh24(u8 *net)
 	return be32_to_cpu(t);
 }
 
+#define SMC_BUF_MIN_SIZE 16384		/* minimum size of an RMB */
+
+#define SMC_RMBE_SIZES	16	/* number of distinct sizes for an RMBE */
+/* theoretically, the RFC states that largest size would be 512K,
+ * i.e. compressed 5 and thus 6 sizes (0..5), despite
+ * struct smc_clc_msg_accept_confirm.rmbe_size being a 4 bit value (0..15)
+ */
+
+/* convert the RMB size into the compressed notation - minimum 16K.
+ * In contrast to plain ilog2, this rounds towards the next power of 2,
+ * so the socket application gets at least its desired sndbuf / rcvbuf size.
+ */
+static inline u8 smc_compress_bufsize(int size)
+{
+	u8 compressed;
+
+	if (size <= SMC_BUF_MIN_SIZE)
+		return 0;
+
+	size = (size - 1) >> 14;
+	compressed = ilog2(size) + 1;
+	if (compressed >= SMC_RMBE_SIZES)
+		compressed = SMC_RMBE_SIZES - 1;
+	return compressed;
+}
+
+/* convert the RMB size from compressed notation into integer */
+static inline int smc_uncompress_bufsize(u8 compressed)
+{
+	u32 size;
+
+	size = 0x00000001 << (((int)compressed) + 14);
+	return (int)size;
+}
+
 #ifdef CONFIG_XFRM
 static inline bool using_ipsec(struct smc_sock *smc)
 {