Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / fs / dlm / midcomms.c

diff --git a/kernel/fs/dlm/midcomms.c b/kernel/fs/dlm/midcomms.c
new file mode 100644 (file)
index 0000000..f3396c6
--- /dev/null
+++ b/kernel/fs/dlm/midcomms.c
@@ -0,0 +1,137 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
+**
+**  This copyrighted material is made available to anyone wishing to use,
+**  modify, copy, or redistribute it subject to the terms and conditions
+**  of the GNU General Public License v.2.
+**
+*******************************************************************************
+******************************************************************************/
+
+/*
+ * midcomms.c
+ *
+ * This is the appallingly named "mid-level" comms layer.
+ *
+ * Its purpose is to take packets from the "real" comms layer,
+ * split them up into packets and pass them to the interested
+ * part of the locking mechanism.
+ *
+ * It also takes messages from the locking layer, formats them
+ * into packets and sends them to the comms layer.
+ */
+
+#include "dlm_internal.h"
+#include "lowcomms.h"
+#include "config.h"
+#include "lock.h"
+#include "midcomms.h"
+
+
+static void copy_from_cb(void *dst, const void *base, unsigned offset,
+                        unsigned len, unsigned limit)
+{
+       unsigned copy = len;
+
+       if ((copy + offset) > limit)
+               copy = limit - offset;
+       memcpy(dst, base + offset, copy);
+       len -= copy;
+       if (len)
+               memcpy(dst + copy, base, len);
+}
+
+/*
+ * Called from the low-level comms layer to process a buffer of
+ * commands.
+ *
+ * Only complete messages are processed here, any "spare" bytes from
+ * the end of a buffer are saved and tacked onto the front of the next
+ * message that comes in. I doubt this will happen very often but we
+ * need to be able to cope with it and I don't want the task to be waiting
+ * for packets to come in when there is useful work to be done.
+ */
+
+int dlm_process_incoming_buffer(int nodeid, const void *base,
+                               unsigned offset, unsigned len, unsigned limit)
+{
+       union {
+               unsigned char __buf[DLM_INBUF_LEN];
+               /* this is to force proper alignment on some arches */
+               union dlm_packet p;
+       } __tmp;
+       union dlm_packet *p = &__tmp.p;
+       int ret = 0;
+       int err = 0;
+       uint16_t msglen;
+       uint32_t lockspace;
+
+       while (len > sizeof(struct dlm_header)) {
+
+               /* Copy just the header to check the total length.  The
+                  message may wrap around the end of the buffer back to the
+                  start, so we need to use a temp buffer and copy_from_cb. */
+
+               copy_from_cb(p, base, offset, sizeof(struct dlm_header),
+                            limit);
+
+               msglen = le16_to_cpu(p->header.h_length);
+               lockspace = p->header.h_lockspace;
+
+               err = -EINVAL;
+               if (msglen < sizeof(struct dlm_header))
+                       break;
+               if (p->header.h_cmd == DLM_MSG) {
+                       if (msglen < sizeof(struct dlm_message))
+                               break;
+               } else {
+                       if (msglen < sizeof(struct dlm_rcom))
+                               break;
+               }
+               err = -E2BIG;
+               if (msglen > dlm_config.ci_buffer_size) {
+                       log_print("message size %d from %d too big, buf len %d",
+                                 msglen, nodeid, len);
+                       break;
+               }
+               err = 0;
+
+               /* If only part of the full message is contained in this
+                  buffer, then do nothing and wait for lowcomms to call
+                  us again later with more data.  We return 0 meaning
+                  we've consumed none of the input buffer. */
+
+               if (msglen > len)
+                       break;
+
+               /* Allocate a larger temp buffer if the full message won't fit
+                  in the buffer on the stack (which should work for most
+                  ordinary messages). */
+
+               if (msglen > sizeof(__tmp) && p == &__tmp.p) {
+                       p = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS);
+                       if (p == NULL)
+                               return ret;
+               }
+
+               copy_from_cb(p, base, offset, msglen, limit);
+
+               BUG_ON(lockspace != p->header.h_lockspace);
+
+               ret += msglen;
+               offset += msglen;
+               offset &= (limit - 1);
+               len -= msglen;
+
+               dlm_receive_buffer(p, nodeid);
+       }
+
+       if (p != &__tmp.p)
+               kfree(p);
+
+       return err ? err : ret;
+}
+