1 /****************************************************************************** 2 ******************************************************************************* 3 ** 4 ** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved. 5 ** Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved. 6 ** 7 ** This copyrighted material is made available to anyone wishing to use, 8 ** modify, copy, or redistribute it subject to the terms and conditions 9 ** of the GNU General Public License v.2. 10 ** 11 ******************************************************************************* 12 ******************************************************************************/ 13 14 /* 15 * midcomms.c 16 * 17 * This is the appallingly named "mid-level" comms layer. 18 * 19 * Its purpose is to take packets from the "real" comms layer, 20 * split them up into packets and pass them to the interested 21 * part of the locking mechanism. 22 * 23 * It also takes messages from the locking layer, formats them 24 * into packets and sends them to the comms layer. 25 */ 26 27 #include "dlm_internal.h" 28 #include "lowcomms.h" 29 #include "config.h" 30 #include "rcom.h" 31 #include "lock.h" 32 #include "midcomms.h" 33 34 35 static void copy_from_cb(void *dst, const void *base, unsigned offset, 36 unsigned len, unsigned limit) 37 { 38 unsigned copy = len; 39 40 if ((copy + offset) > limit) 41 copy = limit - offset; 42 memcpy(dst, base + offset, copy); 43 len -= copy; 44 if (len) 45 memcpy(dst + copy, base, len); 46 } 47 48 /* 49 * Called from the low-level comms layer to process a buffer of 50 * commands. 51 * 52 * Only complete messages are processed here, any "spare" bytes from 53 * the end of a buffer are saved and tacked onto the front of the next 54 * message that comes in. I doubt this will happen very often but we 55 * need to be able to cope with it and I don't want the task to be waiting 56 * for packets to come in when there is useful work to be done. 57 */ 58 59 int dlm_process_incoming_buffer(int nodeid, const void *base, 60 unsigned offset, unsigned len, unsigned limit) 61 { 62 unsigned char __tmp[DLM_INBUF_LEN]; 63 struct dlm_header *msg = (struct dlm_header *) __tmp; 64 int ret = 0; 65 int err = 0; 66 uint16_t msglen; 67 uint32_t lockspace; 68 69 while (len > sizeof(struct dlm_header)) { 70 71 /* Copy just the header to check the total length. The 72 message may wrap around the end of the buffer back to the 73 start, so we need to use a temp buffer and copy_from_cb. */ 74 75 copy_from_cb(msg, base, offset, sizeof(struct dlm_header), 76 limit); 77 78 msglen = le16_to_cpu(msg->h_length); 79 lockspace = msg->h_lockspace; 80 81 err = -EINVAL; 82 if (msglen < sizeof(struct dlm_header)) 83 break; 84 err = -E2BIG; 85 if (msglen > dlm_config.ci_buffer_size) { 86 log_print("message size %d from %d too big, buf len %d", 87 msglen, nodeid, len); 88 break; 89 } 90 err = 0; 91 92 /* If only part of the full message is contained in this 93 buffer, then do nothing and wait for lowcomms to call 94 us again later with more data. We return 0 meaning 95 we've consumed none of the input buffer. */ 96 97 if (msglen > len) 98 break; 99 100 /* Allocate a larger temp buffer if the full message won't fit 101 in the buffer on the stack (which should work for most 102 ordinary messages). */ 103 104 if (msglen > sizeof(__tmp) && 105 msg == (struct dlm_header *) __tmp) { 106 msg = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL); 107 if (msg == NULL) 108 return ret; 109 } 110 111 copy_from_cb(msg, base, offset, msglen, limit); 112 113 BUG_ON(lockspace != msg->h_lockspace); 114 115 ret += msglen; 116 offset += msglen; 117 offset &= (limit - 1); 118 len -= msglen; 119 120 switch (msg->h_cmd) { 121 case DLM_MSG: 122 dlm_receive_message(msg, nodeid, 0); 123 break; 124 125 case DLM_RCOM: 126 dlm_receive_rcom(msg, nodeid); 127 break; 128 129 default: 130 log_print("unknown msg type %x from %u: %u %u %u %u", 131 msg->h_cmd, nodeid, msglen, len, offset, ret); 132 } 133 } 134 135 if (msg != (struct dlm_header *) __tmp) 136 kfree(msg); 137 138 return err ? err : ret; 139 } 140 141