MFC r313731: Do not rely on data alignment after m_pullup().

In general case m_pullup() does not really guarantee any data alignment.
Instead of depenting on side effects caused by data being always copied
out of mbuf cluster (which is probably a bug by itself), always allocate
aligned BHS buffer and read data there directly from socket.

While there, reuse new icl_conn_receive_buf() function to read digests.
The code could probably be even more optimized to aggregate those reads,
but until that done, this is still easier then the way it was before.

1 files changed, 44 insertions, 35 deletions

diff --git a/sys/dev/iscsi/icl_soft.c b/sys/dev/iscsi/icl_soft.c
index bcb4387..cde2b47 100644
--- a/sys/dev/iscsi/icl_soft.c
+++ b/sys/dev/iscsi/icl_soft.c
@@ -169,6 +169,40 @@ icl_conn_receive(struct icl_conn *ic, size_t len)
 	return (m);
 }
 
+static int
+icl_conn_receive_buf(struct icl_conn *ic, void *buf, size_t len)
+{
+	struct iovec iov[1];
+	struct uio uio;
+	struct socket *so;
+	int error, flags;
+
+	so = ic->ic_socket;
+
+	memset(&uio, 0, sizeof(uio));
+	iov[0].iov_base = buf;
+	iov[0].iov_len = len;
+	uio.uio_iov = iov;
+	uio.uio_iovcnt = 1;
+	uio.uio_offset = 0;
+	uio.uio_resid = len;
+	uio.uio_segflg = UIO_SYSSPACE;
+	uio.uio_rw = UIO_READ;
+
+	flags = MSG_DONTWAIT;
+	error = soreceive(so, NULL, &uio, NULL, NULL, &flags);
+	if (error != 0) {
+		ICL_DEBUG("soreceive error %d", error);
+		return (-1);
+	}
+	if (uio.uio_resid != 0) {
+		ICL_DEBUG("short read");
+		return (-1);
+	}
+
+	return (0);
+}
+
 static struct icl_pdu *
 icl_pdu_new_empty(struct icl_conn *ic, int flags)
 {
@@ -229,7 +263,7 @@ icl_soft_conn_new_pdu(struct icl_conn *ic, int flags)
 	ip->ip_bhs_mbuf = m_getm2(NULL, sizeof(struct iscsi_bhs),
 	    flags, MT_DATA, M_PKTHDR);
 	if (ip->ip_bhs_mbuf == NULL) {
-		ICL_WARN("failed to allocate %zd bytes", sizeof(*ip));
+		ICL_WARN("failed to allocate BHS mbuf");
 		icl_pdu_free(ip);
 		return (NULL);
 	}
@@ -308,28 +342,13 @@ icl_pdu_size(const struct icl_pdu *response)
 static int
 icl_pdu_receive_bhs(struct icl_pdu *request, size_t *availablep)
 {
-	struct mbuf *m;
 
-	m = icl_conn_receive(request->ip_conn, sizeof(struct iscsi_bhs));
-	if (m == NULL) {
+	if (icl_conn_receive_buf(request->ip_conn,
+	    request->ip_bhs, sizeof(struct iscsi_bhs))) {
 		ICL_DEBUG("failed to receive BHS");
 		return (-1);
 	}
 
-	request->ip_bhs_mbuf = m_pullup(m, sizeof(struct iscsi_bhs));
-	if (request->ip_bhs_mbuf == NULL) {
-		ICL_WARN("m_pullup failed");
-		return (-1);
-	}
-	request->ip_bhs = mtod(request->ip_bhs_mbuf, struct iscsi_bhs *);
-
-	/*
-	 * XXX: For architectures with strict alignment requirements
-	 * 	we may need to allocate ip_bhs and copy the data into it.
-	 * 	For some reason, though, not doing this doesn't seem
-	 * 	to cause problems; tested on sparc64.
-	 */
-
 	*availablep -= sizeof(struct iscsi_bhs);
 	return (0);
 }
@@ -371,22 +390,17 @@ icl_mbuf_to_crc32c(const struct mbuf *m0)
 static int
 icl_pdu_check_header_digest(struct icl_pdu *request, size_t *availablep)
 {
-	struct mbuf *m;
 	uint32_t received_digest, valid_digest;
 
 	if (request->ip_conn->ic_header_crc32c == false)
 		return (0);
 
-	m = icl_conn_receive(request->ip_conn, ISCSI_HEADER_DIGEST_SIZE);
-	if (m == NULL) {
+	CTASSERT(sizeof(received_digest) == ISCSI_HEADER_DIGEST_SIZE);
+	if (icl_conn_receive_buf(request->ip_conn,
+	    &received_digest, ISCSI_HEADER_DIGEST_SIZE)) {
 		ICL_DEBUG("failed to receive header digest");
 		return (-1);
 	}
-
-	CTASSERT(sizeof(received_digest) == ISCSI_HEADER_DIGEST_SIZE);
-	m_copydata(m, 0, ISCSI_HEADER_DIGEST_SIZE, (void *)&received_digest);
-	m_freem(m);
-
 	*availablep -= ISCSI_HEADER_DIGEST_SIZE;
 
 	/* Temporary attach AHS to BHS to calculate header digest. */
@@ -526,7 +540,6 @@ icl_pdu_receive_data_segment(struct icl_pdu *request,
 static int
 icl_pdu_check_data_digest(struct icl_pdu *request, size_t *availablep)
 {
-	struct mbuf *m;
 	uint32_t received_digest, valid_digest;
 
 	if (request->ip_conn->ic_data_crc32c == false)
@@ -535,16 +548,12 @@ icl_pdu_check_data_digest(struct icl_pdu *request, size_t *availablep)
 	if (request->ip_data_len == 0)
 		return (0);
 
-	m = icl_conn_receive(request->ip_conn, ISCSI_DATA_DIGEST_SIZE);
-	if (m == NULL) {
+	CTASSERT(sizeof(received_digest) == ISCSI_DATA_DIGEST_SIZE);
+	if (icl_conn_receive_buf(request->ip_conn,
+	    &received_digest, ISCSI_DATA_DIGEST_SIZE)) {
 		ICL_DEBUG("failed to receive data digest");
 		return (-1);
 	}
-
-	CTASSERT(sizeof(received_digest) == ISCSI_DATA_DIGEST_SIZE);
-	m_copydata(m, 0, ISCSI_DATA_DIGEST_SIZE, (void *)&received_digest);
-	m_freem(m);
-
 	*availablep -= ISCSI_DATA_DIGEST_SIZE;
 
 	/*
@@ -580,7 +589,7 @@ icl_conn_receive_pdu(struct icl_conn *ic, size_t *availablep)
 	if (ic->ic_receive_state == ICL_CONN_STATE_BHS) {
 		KASSERT(ic->ic_receive_pdu == NULL,
 		    ("ic->ic_receive_pdu != NULL"));
-		request = icl_pdu_new_empty(ic, M_NOWAIT);
+		request = icl_soft_conn_new_pdu(ic, M_NOWAIT);
 		if (request == NULL) {
 			ICL_DEBUG("failed to allocate PDU; "
 			    "dropping connection");