1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * CDDL HEADER START
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1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Common Development and Distribution License (the "License").
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * You may not use this file except in compliance with the License.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * See the License for the specific language governing permissions
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * and limitations under the License.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * When distributing Covered Code, include this CDDL HEADER in each
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * If applicable, add the following below this CDDL HEADER, with the
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * fields enclosed by brackets "[]" replaced with your own identifying
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * information: Portions Copyright [yyyy] [name of copyright owner]
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * CDDL HEADER END
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * DR control module for LDoms
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedastatic int drctl_attach(dev_info_t *, ddi_attach_cmd_t);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedastatic int drctl_detach(dev_info_t *, ddi_detach_cmd_t);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedastatic int drctl_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedastatic int drctl_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystemsstatic void *pack_message(int, int, int, void *, size_t *, size_t *);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystemsstatic int send_message(void *, size_t, drctl_resp_t **, size_t *);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Configuration data structures
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda 0, /* refcnt */
193974072f41a843678abf5f61979c748687e66bSherry Moore "DR Control pseudo driver",
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Locking strategy
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * One of the reasons for this module's existence is to serialize
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * DR requests which might be coming from different sources. Only
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * one operation is allowed to be in progress at any given time.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * A single lock word (the 'drc_busy' element below) is NULL
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * when there is no operation in progress. When a client of this
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * module initiates an operation it grabs the mutex 'drc_lock' in
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * order to examine the lock word ('drc_busy'). If no other
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * operation is in progress, the lock word will be NULL. If so,
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * a cookie which uniquely identifies the requestor is stored in
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * the lock word, and the mutex is released. Attempts by other
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * clients to initiate an operation will fail.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * When the lock-holding client's operation is completed, the
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * client will call a "finalize" function in this module, providing
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * the cookie passed with the original request. Since the cookie
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * matches, the operation will succeed and the lock word will be
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * cleared. At this point, an new operation may be initiated.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Driver private data
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda drctl_cookie_t drc_busy; /* NULL if free else a unique */
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda /* identifier for caller */
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda mutex_init(&drctlp->drc_lock, NULL, MUTEX_DRIVER, NULL);
af4c679f647cf088543c762e33d41a3ac52cfa14Sean McEnroe cv_init(&drctlp->drc_busy_cv, NULL, CV_DRIVER, NULL);
e1ebb9ec908bc2d0a8810f137ebd6566cc8a8061lm return (rv);
e1ebb9ec908bc2d0a8810f137ebd6566cc8a8061lm return (rv);
e1ebb9ec908bc2d0a8810f137ebd6566cc8a8061lm return (0);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Do the attach work
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_do_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda cmn_err(CE_WARN, "%s: an instance is already attached!", str);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda retval = ddi_create_minor_node(dip, "drctl", S_IFCHR,
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda cmn_err(CE_WARN, "%s: can't create minor node", str);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda/* ARGSUSED */
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg, void **resultp)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda return (0);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda return (0);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_close(dev_t dev, int flag, int otyp, cred_t *cred_p)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda return (0);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * Create a reponse structure which includes an array of drctl_rsrc_t
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * structures in which each status element is set to the 'status'
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * arg. There is no error text, so set the 'offset' elements to 0.
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems size = offsetof(drctl_resp_t, resp_resources) + (count * sizeof (*res));
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems resp = kmem_alloc(size, KM_SLEEP);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s: alloc addr %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)resp, size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems resp->resp_type = DRCTL_RESP_OK;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems bcopy(res, rsrc, count * sizeof (*res));
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems for (i = 0; i < count; i++) {
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * Generate an error response message.
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystemsdrctl_generate_err_resp(char *msg, size_t *size)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *size = offsetof(drctl_resp_t, resp_err_msg) + strlen(msg) + 1;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems resp = kmem_alloc(*size, KM_SLEEP);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s: alloc addr %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)resp, *size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems resp->resp_type = DRCTL_RESP_ERR;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems (void) strcpy(resp->resp_err_msg, msg);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * Since response comes from userland, verify that it is at least the
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * minimum size based on the size of the original request. Verify
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * that any offsets to error strings are within the string area of
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * the response and, force the string area to be null-terminated.
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems int count, drctl_resp_t *resp, size_t sent_len, size_t resp_len)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems drctl_rsrc_t *rsrc = resp->resp_resources;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems size_t rcvd_len = resp_len - (offsetof(drctl_resp_t, resp_resources));
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems case DRCTL_CPU_CONFIG_REQUEST:
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems case DRCTL_CPU_UNCONFIG_REQUEST:
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems case DRCTL_IO_UNCONFIG_REQUEST:
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems case DRCTL_IO_CONFIG_REQUEST:
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems for (i = 0; i < count; i++)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems /* string can't be inside the bounds of original request */
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems (((rsrc[i].offset < sent_len) && is_cpu) ||
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems /* string must start inside the message */
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems (rsrc[i].offset >= rcvd_len)))
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems /* If there are any strings, terminate the string area. */
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *((char *)rsrc + rcvd_len - 1) = '\0';
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_config_common(int cmd, int flags, drctl_rsrc_t *res,
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems int count, drctl_resp_t **rbuf, size_t *rsize, size_t *rq_size)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda if (rv != 0) {
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_CTL("%s: invalid cmd %d\n", __func__, cmd);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * If the operation is a FORCE, we don't send a message to
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * the daemon. But, the upstream clients still expect a
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * response, so generate a response with all ops 'allowed'.
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *rbuf = drctl_generate_resp(res,
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems count, rsize, DRCTL_STATUS_ALLOW);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda return (0);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems bufp = pack_message(cmd, flags, count, (void *)res, &size, rq_size);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda DR_DBG_CTL("%s: from pack_message, bufp = %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)bufp, size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems if (bufp == NULL || size == 0)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems return (send_message(bufp, size, rbuf, rsize));
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Prepare for a reconfig operation.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_config_init(int cmd, int flags, drctl_rsrc_t *res,
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems int count, drctl_resp_t **rbuf, size_t *rsize, drctl_cookie_t ck)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems static char inval_msg[] = "Invalid command format received.\n";
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems static char unsup_msg[] = "Unsuppported command received.\n";
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems static char unk_msg [] = "Failure reason unknown.\n";
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems static char rsp_msg [] = "Invalid response from "
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems "reconfiguration daemon.\n";
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems static char drd_msg [] = "Cannot communicate with reconfiguration "
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems "daemon (drd) in target domain.\n"
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems "drd(1M) SMF service may not be enabled.\n";
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems static char busy_msg [] = "Busy executing earlier command; "
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems "please try again later.\n";
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *rbuf = drctl_generate_err_resp(inval_msg, rsize);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *rbuf = drctl_generate_err_resp(busy_msg, rsize);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, cmd, flags, (void *)res, count);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda /* Mark the link busy. Below we will fill in the actual cookie. */
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems rv = drctl_config_common(cmd, flags, res, count, rbuf, rsize, &rq_size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * If the upcall to the daemon returned successfully, we
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems * still need to validate the format of the returned msg.
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems if ((rv = verify_response(cmd,
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems count, *rbuf, rq_size, *rsize)) != 0) {
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s: free addr %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)*rbuf, *rsize);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *rbuf = drctl_generate_err_resp(rsp_msg, rsize);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems } else { /* message format is valid */
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *rbuf = drctl_generate_err_resp(ermsg, rsize);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Complete a reconfig operation.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedadrctl_config_fini(drctl_cookie_t ck, drctl_rsrc_t *res, int count)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Flip the saved _REQUEST command to its corresponding
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * _NOTIFY command.
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda /* none of the above should have been accepted in _init */
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda "drctl_config_fini: bad cmd %d\n", drctlp->drc_cmd);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems rv = drctl_config_common(notify_cmd,
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems flags, res, count, NULL, 0, &rq_size);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda int cmd, intptr_t arg, int mode, cred_t *cred_p, int *rval_p)
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * Accept a preformatted request from caller and send a message to
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * the daemon. A pointer to the daemon's response buffer is passed
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaeda * back in obufp, its size in osize.
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystemssend_message(void *msg, size_t size, drctl_resp_t **obufp, size_t *osize)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems rv = i_drctl_send(msg, size, (void **)&rsrcs, &rsrcs_size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems if ((rv == 0) && ((rsrcs == NULL) ||(rsrcs_size == 0)))
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems offsetof(drctl_resp_t, resp_resources) + rsrcs_size;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems kmem_alloc(*osize, KM_SLEEP);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s: alloc addr %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)bufp, *osize);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems bufp->resp_type = DRCTL_RESP_OK;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems bcopy(rsrcs, bufp->resp_resources, rsrcs_size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s: free addr %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)rsrcs, rsrcs_size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems kmem_free(rsrcs, rsrcs_size);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s:free addr %p size %ld\n", __func__, msg, size);
1d4b38e0077763e7c9b20768eacb841957e787bcrsmaedastatic void *
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems int flags, int count, void *data, size_t *osize, size_t *data_size)
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *data_size = count * sizeof (drctl_rsrc_t);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *data_size = sizeof (drctl_rsrc_t) +
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems *osize = hdr_size + *data_size;
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems DR_DBG_KMEM("%s: alloc addr %p size %ld\n",
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems __func__, (void *)msgp, *osize);
99c7e85592b5d673f1469b2767f876710004dc23James Marks - Sun Microsystems bcopy(data, msgp->data, *data_size);
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * Depending on the should_block argument, either wait for ongoing DR
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * operations to finish and then block subsequent operations, or if a DR
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * operation is already in progress, return EBUSY immediately without
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * blocking subsequent DR operations.
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandiliandrctl_block_conditional(boolean_t should_block)
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian /* If DR in progress and should_block is false, return */
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian if (!should_block && drctlp->drc_busy != NULL) {
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian /* Wait for any in progress DR operation to complete */
af4c679f647cf088543c762e33d41a3ac52cfa14Sean McEnroe (void) cv_wait_sig(&drctlp->drc_busy_cv, &drctlp->drc_lock);
af4c679f647cf088543c762e33d41a3ac52cfa14Sean McEnroe /* Mark the link busy */
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * Wait for ongoing DR operations to finish, block subsequent operations.
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * If a DR operation is already in progress, return EBUSY immediately
02b4e56ca3a4e4a4fe9e52fca9c2972101f0e57fHaik Aftandilian * without blocking subsequent DR operations.
af4c679f647cf088543c762e33d41a3ac52cfa14Sean McEnroe * Unblock DR operations
af4c679f647cf088543c762e33d41a3ac52cfa14Sean McEnroe /* Mark the link free */