[PATCH] CIFS: Simplify cifs_demultiplex_thread

[Pavel Shilovsky <piastryyy-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Move several code blocks to separate functions:
1) buffer allocations,
2) rfc1002 header check,
3) read whole smb message from socket,
4) find mid owner.

Signed-off-by: Pavel Shilovsky <piastry-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 fs/cifs/cifs_debug.c |    1 -
 fs/cifs/connect.c    |  440 ++++++++++++++++++++++++++++----------------------
 2 files changed, 247 insertions(+), 194 deletions(-)

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 2fe3cf1..c4fc68a 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -66,7 +66,6 @@ void cifs_dump_detail(struct smb_hdr *smb)
 	cERROR(1, "smb buf %p len %d", smb, smbCalcSize(smb));
 }
 
-
 void cifs_dump_mids(struct TCP_Server_Info *server)
 {
 	struct list_head *tmp;
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index fb31c2c..23addcb 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -317,24 +317,234 @@ requeue_echo:
 	queue_delayed_work(system_nrt_wq, &server->echo, SMB_ECHO_INTERVAL);
 }
 
+static struct mid_q_entry *
+find_cifs_owner(struct TCP_Server_Info *server, struct smb_hdr *buf,
+		int *length, bool isLargeBuf, bool *isMultiRsp, char **pbigbuf)
+{
+	struct list_head *tmp, *tmp2;
+	struct mid_q_entry *mid_entry = NULL;
+
+	spin_lock(&GlobalMid_Lock);
+	list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
+		mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
+
+		if (mid_entry->mid != buf->Mid ||
+		    mid_entry->midState != MID_REQUEST_SUBMITTED ||
+		    mid_entry->command != buf->Command) {
+			mid_entry = NULL;
+			continue;
+		}
+
+		if (*length == 0 && check2ndT2(buf, server->maxBuf) > 0) {
+			/* We have a multipart transact2 resp */
+			*isMultiRsp = true;
+			if (mid_entry->resp_buf) {
+				/* merge response - fix up 1st*/
+				*length = coalesce_t2(buf, mid_entry->resp_buf);
+				if (*length > 0) {
+					*length = 0;
+					mid_entry->multiRsp = true;
+					break;
+				} else {
+					/* all parts received or
+					 * packet is malformed
+					 */
+					mid_entry->multiEnd = true;
+					goto multi_t2_fnd;
+				}
+			} else {
+				if (!isLargeBuf) {
+					/*
+					 * FIXME: switch to already
+					 *        allocated largebuf?
+					 */
+					cERROR(1, "1st trans2 resp "
+						  "needs bigbuf");
+				} else {
+					/* Have first buffer */
+					mid_entry->resp_buf = buf;
+					mid_entry->largeBuf = true;
+					*pbigbuf = NULL;
+				}
+			}
+			break;
+		}
+		mid_entry->resp_buf = buf;
+		mid_entry->largeBuf = isLargeBuf;
+multi_t2_fnd:
+		if (*length == 0)
+			mid_entry->midState = MID_RESPONSE_RECEIVED;
+		else
+			mid_entry->midState = MID_RESPONSE_MALFORMED;
+#ifdef CONFIG_CIFS_STATS2
+		mid_entry->when_received = jiffies;
+#endif
+		list_del_init(&mid_entry->qhead);
+		break;
+	}
+	spin_unlock(&GlobalMid_Lock);
+
+	return mid_entry;
+}
+
+static int
+check_rfc1002_header(struct TCP_Server_Info *server, char *buf, int length,
+		     unsigned int pdu_length, struct socket **psocket)
+{
+	char temp = *buf;
+
+	/*
+	 * The first byte big endian of the length field,
+	 * is actually not part of the length but the type
+	 * with the most common, zero, as regular data.
+	 */
+	if (temp == (char) RFC1002_SESSION_KEEP_ALIVE) {
+		return 1;
+	} else if (temp == (char)RFC1002_POSITIVE_SESSION_RESPONSE) {
+		cFYI(1, "Good RFC 1002 session rsp");
+		return 1;
+	} else if (temp == (char)RFC1002_NEGATIVE_SESSION_RESPONSE) {
+		/* we get this from Windows 98 instead of
+		   an error on SMB negprot response */
+		cFYI(1, "Negative RFC1002 Session Response Error 0x%x)",
+			pdu_length);
+		/* give server a second to clean up  */
+		msleep(1000);
+		/* always try 445 first on reconnect since we get NACK
+		 * on some if we ever connected to port 139 (the NACK
+		 * is since we do not begin with RFC1001 session
+		 * initialize frame)
+		 */
+		cifs_set_port((struct sockaddr *)
+				&server->dstaddr, CIFS_PORT);
+		cifs_reconnect(server);
+		*psocket = server->ssocket;
+		wake_up(&server->response_q);
+		return 1;
+	} else if (temp != (char) 0) {
+		cERROR(1, "Unknown RFC 1002 frame");
+		cifs_dump_mem(" Received Data: ", buf, length);
+		cifs_reconnect(server);
+		*psocket = server->ssocket;
+		return 1;
+	}
+
+	/* else we have an SMB response */
+	if ((pdu_length > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) ||
+	    (pdu_length < sizeof(struct smb_hdr) - 1 - 4)) {
+		cERROR(1, "Invalid size SMB length %d pdu_length %d",
+		       length, pdu_length+4);
+		cifs_reconnect(server);
+		*psocket = server->ssocket;
+		wake_up(&server->response_q);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int
+allocate_bufs(char **pbigbuf, char **psmallbuf, unsigned int size,
+	      bool isLargeBuf)
+{
+	char *bigbuf = *pbigbuf, *smallbuf = *psmallbuf;
+
+	if (bigbuf == NULL) {
+		bigbuf = (char *)cifs_buf_get();
+		if (!bigbuf) {
+			cERROR(1, "No memory for large SMB response");
+			msleep(3000);
+			/* retry will check if exiting */
+			return 1;
+		}
+	} else if (isLargeBuf) {
+		/* we are reusing a dirty large buf, clear its start */
+		memset(bigbuf, 0, size);
+	}
+
+	if (smallbuf == NULL) {
+		smallbuf = (char *)cifs_small_buf_get();
+		if (!smallbuf) {
+			cERROR(1, "No memory for SMB response");
+			msleep(1000);
+			/* retry will check if exiting */
+			return 1;
+		}
+		/* beginning of smb buffer is cleared in our buf_get */
+	} else /* if existing small buf clear beginning */
+		memset(smallbuf, 0, size);
+
+	*pbigbuf = bigbuf;
+	*psmallbuf = smallbuf;
+
+	return 0;
+}
+
+static int
+read_from_socket(struct TCP_Server_Info *server, unsigned int pdu_length,
+		 struct socket **psocket, struct msghdr *smb_msg,
+		 struct kvec *iov, unsigned int *ptotal_read)
+{
+	int length, rc = 0;
+	unsigned int total_read;
+
+	for (total_read = 0; total_read < pdu_length;
+	     total_read += length) {
+		length = kernel_recvmsg(*psocket, smb_msg, iov, 1,
+					pdu_length - total_read, 0);
+		if (server->tcpStatus == CifsExiting) {
+			/* then will exit */
+			rc = 2;
+			break;
+		} else if (server->tcpStatus == CifsNeedReconnect) {
+			cifs_reconnect(server);
+			*psocket = server->ssocket;
+			/* Reconnect wakes up rspns q */
+			/* Now we will reread sock */
+			rc = 1;
+			break;
+		} else if (length == -ERESTARTSYS ||
+			   length == -EAGAIN ||
+			   length == -EINTR) {
+			/*
+			 * Minimum sleep to prevent looping,
+			 * allowing socket to clear and app
+			 * threads to set tcpStatus
+			 * CifsNeedReconnect if server hung.
+			 */
+			usleep_range(1000, 2000);
+			length = 0;
+			continue;
+		} else if (length <= 0) {
+			cERROR(1, "Received no data, expecting %d",
+				      pdu_length - total_read);
+			cifs_reconnect(server);
+			*psocket = server->ssocket;
+			rc = 1;
+			break;
+		}
+	}
+
+	*ptotal_read = total_read;
+	return 0;
+}
+
 static int
 cifs_demultiplex_thread(struct TCP_Server_Info *server)
 {
 	int length;
 	unsigned int pdu_length, total_read;
+	char *buf = NULL, *smallbuf = NULL, *bigbuf = NULL;
 	struct smb_hdr *smb_buffer = NULL;
-	struct smb_hdr *bigbuf = NULL;
-	struct smb_hdr *smallbuf = NULL;
 	struct msghdr smb_msg;
 	struct kvec iov;
 	struct socket *csocket = server->ssocket;
 	struct list_head *tmp, *tmp2;
 	struct task_struct *task_to_wake = NULL;
 	struct mid_q_entry *mid_entry;
-	char temp;
 	bool isLargeBuf = false;
 	bool isMultiRsp;
-	int reconnect;
+	int rc;
 
 	current->flags |= PF_MEMALLOC;
 	cFYI(1, "Demultiplex PID: %d", task_pid_nr(current));
@@ -348,35 +558,17 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 	while (server->tcpStatus != CifsExiting) {
 		if (try_to_freeze())
 			continue;
-		if (bigbuf == NULL) {
-			bigbuf = cifs_buf_get();
-			if (!bigbuf) {
-				cERROR(1, "No memory for large SMB response");
-				msleep(3000);
-				/* retry will check if exiting */
-				continue;
-			}
-		} else if (isLargeBuf) {
-			/* we are reusing a dirty large buf, clear its start */
-			memset(bigbuf, 0, sizeof(struct smb_hdr));
-		}
 
-		if (smallbuf == NULL) {
-			smallbuf = cifs_small_buf_get();
-			if (!smallbuf) {
-				cERROR(1, "No memory for SMB response");
-				msleep(1000);
-				/* retry will check if exiting */
-				continue;
-			}
-			/* beginning of smb buffer is cleared in our buf_get */
-		} else /* if existing small buf clear beginning */
-			memset(smallbuf, 0, sizeof(struct smb_hdr));
+		rc = allocate_bufs(&bigbuf, &smallbuf, sizeof(struct smb_hdr),
+				   isLargeBuf);
+		if (rc)
+			continue;
 
 		isLargeBuf = false;
 		isMultiRsp = false;
-		smb_buffer = smallbuf;
-		iov.iov_base = smb_buffer;
+		smb_buffer = (struct smb_hdr *)smallbuf;
+		buf = smallbuf;
+		iov.iov_base = smallbuf;
 		iov.iov_len = 4;
 		smb_msg.msg_control = NULL;
 		smb_msg.msg_controllen = 0;
@@ -414,8 +606,7 @@ incomplete_rcv:
 				allowing socket to clear and app threads to set
 				tcpStatus CifsNeedReconnect if server hung */
 			if (pdu_length < 4) {
-				iov.iov_base = (4 - pdu_length) +
-							(char *)smb_buffer;
+				iov.iov_base = (4 - pdu_length) + buf;
 				iov.iov_len = pdu_length;
 				smb_msg.msg_control = NULL;
 				smb_msg.msg_controllen = 0;
@@ -440,114 +631,42 @@ incomplete_rcv:
 		/* The right amount was read from socket - 4 bytes */
 		/* so we can now interpret the length field */
 
-		/* the first byte big endian of the length field,
-		is actually not part of the length but the type
-		with the most common, zero, as regular data */
-		temp = *((char *) smb_buffer);
-
-		/* Note that FC 1001 length is big endian on the wire,
-		but we convert it here so it is always manipulated
-		as host byte order */
+		/*
+		 * Note that FC 1001 length is big endian on the wire,
+		 * but we convert it here so it is always manipulated
+		 * as host byte order
+		 */
 		pdu_length = be32_to_cpu(smb_buffer->smb_buf_length);
-
-		cFYI(1, "rfc1002 length 0x%x", pdu_length+4);
-
-		if (temp == (char) RFC1002_SESSION_KEEP_ALIVE) {
-			continue;
-		} else if (temp == (char)RFC1002_POSITIVE_SESSION_RESPONSE) {
-			cFYI(1, "Good RFC 1002 session rsp");
-			continue;
-		} else if (temp == (char)RFC1002_NEGATIVE_SESSION_RESPONSE) {
-			/* we get this from Windows 98 instead of
-			   an error on SMB negprot response */
-			cFYI(1, "Negative RFC1002 Session Response Error 0x%x)",
-				pdu_length);
-			/* give server a second to clean up  */
-			msleep(1000);
-			/* always try 445 first on reconnect since we get NACK
-			 * on some if we ever connected to port 139 (the NACK
-			 * is since we do not begin with RFC1001 session
-			 * initialize frame)
-			 */
-			cifs_set_port((struct sockaddr *)
-					&server->dstaddr, CIFS_PORT);
-			cifs_reconnect(server);
-			csocket = server->ssocket;
-			wake_up(&server->response_q);
-			continue;
-		} else if (temp != (char) 0) {
-			cERROR(1, "Unknown RFC 1002 frame");
-			cifs_dump_mem(" Received Data: ", (char *)smb_buffer,
-				      length);
-			cifs_reconnect(server);
-			csocket = server->ssocket;
-			continue;
-		}
-
-		/* else we have an SMB response */
-		if ((pdu_length > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) ||
-			    (pdu_length < sizeof(struct smb_hdr) - 1 - 4)) {
-			cERROR(1, "Invalid size SMB length %d pdu_length %d",
-					length, pdu_length+4);
-			cifs_reconnect(server);
-			csocket = server->ssocket;
-			wake_up(&server->response_q);
+		rc = check_rfc1002_header(server, buf, length, pdu_length,
+					  &csocket);
+		if (rc)
 			continue;
-		}
 
-		/* else length ok */
-		reconnect = 0;
+		cFYI(1, "rfc1002 length 0x%x", pdu_length+4);
 
 		if (pdu_length > MAX_CIFS_SMALL_BUFFER_SIZE - 4) {
 			isLargeBuf = true;
 			memcpy(bigbuf, smallbuf, 4);
-			smb_buffer = bigbuf;
+			smb_buffer = (struct smb_hdr *)bigbuf;
+			buf = bigbuf;
 		}
-		length = 0;
-		iov.iov_base = 4 + (char *)smb_buffer;
+
+		iov.iov_base = 4 + buf;
 		iov.iov_len = pdu_length;
-		for (total_read = 0; total_read < pdu_length;
-		     total_read += length) {
-			length = kernel_recvmsg(csocket, &smb_msg, &iov, 1,
-						pdu_length - total_read, 0);
-			if (server->tcpStatus == CifsExiting) {
-				/* then will exit */
-				reconnect = 2;
-				break;
-			} else if (server->tcpStatus == CifsNeedReconnect) {
-				cifs_reconnect(server);
-				csocket = server->ssocket;
-				/* Reconnect wakes up rspns q */
-				/* Now we will reread sock */
-				reconnect = 1;
-				break;
-			} else if (length == -ERESTARTSYS ||
-				   length == -EAGAIN ||
-				   length == -EINTR) {
-				msleep(1); /* minimum sleep to prevent looping,
-					      allowing socket to clear and app
-					      threads to set tcpStatus
-					      CifsNeedReconnect if server hung*/
-				length = 0;
-				continue;
-			} else if (length <= 0) {
-				cERROR(1, "Received no data, expecting %d",
-					      pdu_length - total_read);
-				cifs_reconnect(server);
-				csocket = server->ssocket;
-				reconnect = 1;
-				break;
-			}
-		}
-		if (reconnect == 2)
+		rc = read_from_socket(server, pdu_length, &csocket, &smb_msg,
+				      &iov, &total_read);
+		if (rc == 2)
 			break;
-		else if (reconnect == 1)
+		else if (rc == 1)
 			continue;
 
 		total_read += 4; /* account for rfc1002 hdr */
 
 		dump_smb(smb_buffer, total_read);
 
+		server->lstrp = jiffies;
+		length = 0;
+
 		/*
 		 * We know that we received enough to get to the MID as we
 		 * checked the pdu_length earlier. Now check to see
@@ -559,75 +678,11 @@ incomplete_rcv:
 		 */
 		length = checkSMB(smb_buffer, smb_buffer->Mid, total_read);
 		if (length != 0)
-			cifs_dump_mem("Bad SMB: ", smb_buffer,
-					min_t(unsigned int, total_read, 48));
-
-		mid_entry = NULL;
-		server->lstrp = jiffies;
-
-		spin_lock(&GlobalMid_Lock);
-		list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
-			mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
-
-			if (mid_entry->mid != smb_buffer->Mid ||
-			    mid_entry->midState != MID_REQUEST_SUBMITTED ||
-			    mid_entry->command != smb_buffer->Command) {
-				mid_entry = NULL;
-				continue;
-			}
-
-			if (length == 0 &&
-			    check2ndT2(smb_buffer, server->maxBuf) > 0) {
-				/* We have a multipart transact2 resp */
-				isMultiRsp = true;
-				if (mid_entry->resp_buf) {
-					/* merge response - fix up 1st*/
-					length = coalesce_t2(smb_buffer,
-							mid_entry->resp_buf);
-					if (length > 0) {
-						length = 0;
-						mid_entry->multiRsp = true;
-						break;
-					} else {
-						/* all parts received or
-						 * packet is malformed
-						 */
-						mid_entry->multiEnd = true;
-						goto multi_t2_fnd;
-					}
-				} else {
-					if (!isLargeBuf) {
-						/*
-						 * FIXME: switch to already
-						 *        allocated largebuf?
-						 */
-						cERROR(1, "1st trans2 resp "
-							  "needs bigbuf");
-					} else {
-						/* Have first buffer */
-						mid_entry->resp_buf =
-							 smb_buffer;
-						mid_entry->largeBuf = true;
-						bigbuf = NULL;
-					}
-				}
-				break;
-			}
-			mid_entry->resp_buf = smb_buffer;
-			mid_entry->largeBuf = isLargeBuf;
-multi_t2_fnd:
-			if (length == 0)
-				mid_entry->midState = MID_RESPONSE_RECEIVED;
-			else
-				mid_entry->midState = MID_RESPONSE_MALFORMED;
-#ifdef CONFIG_CIFS_STATS2
-			mid_entry->when_received = jiffies;
-#endif
-			list_del_init(&mid_entry->qhead);
-			break;
-		}
-		spin_unlock(&GlobalMid_Lock);
+			cifs_dump_mem("Bad SMB: ", buf,
+				      min_t(unsigned int, total_read, 48));
 
+		mid_entry = find_cifs_owner(server, smb_buffer, &length,
+					    isLargeBuf, &isMultiRsp, &bigbuf);
 		if (mid_entry != NULL) {
 			mid_entry->callback(mid_entry);
 			/* Was previous buf put in mpx struct for multi-rsp? */
@@ -645,13 +700,12 @@ multi_t2_fnd:
 			   !isMultiRsp) {
 			cERROR(1, "No task to wake, unknown frame received! "
 				   "NumMids %d", atomic_read(&midCount));
-			cifs_dump_mem("Received Data is: ", (char *)smb_buffer,
+			cifs_dump_mem("Received Data is: ", buf,
 				      sizeof(struct smb_hdr));
 #ifdef CONFIG_CIFS_DEBUG2
 			cifs_dump_detail(smb_buffer);
 			cifs_dump_mids(server);
 #endif /* CIFS_DEBUG2 */
-
 		}
 	} /* end while !EXITING */
 
-- 
1.7.1