drivers/staging/lustre/lustre/obdclass/kernelcomm.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2012, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * Author: Nathan Rutman <nathan.rutman@sun.com>
  33  *
  34  * Kernel <-> userspace communication routines.
  35  * Using pipes for all arches.
  36  */
  37
  38 #define DEBUG_SUBSYSTEM S_CLASS
  39 #define D_KUC D_OTHER
  40
  41 #include <obd_support.h>
  42 #include <lustre_kernelcomm.h>
  43
  44 /**
  45  * libcfs_kkuc_msg_put - send an message from kernel to userspace
  46  * @param fp to send the message to
  47  * @param payload Payload data.  First field of payload is always
  48  *   struct kuc_hdr
  49  */
  50 int libcfs_kkuc_msg_put(struct file *filp, void *payload)
  51 {
  52         struct kuc_hdr *kuch = (struct kuc_hdr *)payload;
  53         ssize_t count = kuch->kuc_msglen;
  54         loff_t offset = 0;
  55         int rc = -ENXIO;
  56
  57         if (IS_ERR_OR_NULL(filp))
  58                 return -EBADF;
  59
  60         if (kuch->kuc_magic != KUC_MAGIC) {
  61                 CERROR("KernelComm: bad magic %x\n", kuch->kuc_magic);
  62                 return rc;
  63         }
  64
  65         while (count > 0) {
  66                 rc = kernel_write(filp, payload, count, &offset);
  67                 if (rc < 0)
  68                         break;
  69                 count -= rc;
  70                 payload += rc;
  71                 rc = 0;
  72         }
  73
  74         if (rc < 0)
  75                 CWARN("message send failed (%d)\n", rc);
  76         else
  77                 CDEBUG(D_KUC, "Sent message rc=%d, fp=%p\n", rc, filp);
  78
  79         return rc;
  80 }
  81 EXPORT_SYMBOL(libcfs_kkuc_msg_put);
  82
  83 /*
  84  * Broadcast groups are global across all mounted filesystems;
  85  * i.e. registering for a group on 1 fs will get messages for that
  86  * group from any fs
  87  */
  88 /** A single group registration has a uid and a file pointer */
  89 struct kkuc_reg {
  90         struct list_head kr_chain;
  91         int              kr_uid;
  92         struct file     *kr_fp;
  93         char             kr_data[0];
  94 };
  95
  96 static struct list_head kkuc_groups[KUC_GRP_MAX + 1] = {};
  97 /* Protect message sending against remove and adds */
  98 static DECLARE_RWSEM(kg_sem);
  99
 100 /** Add a receiver to a broadcast group
 101  * @param filp pipe to write into
 102  * @param uid identifier for this receiver
 103  * @param group group number
 104  * @param data user data
 105  */
 106 int libcfs_kkuc_group_add(struct file *filp, int uid, unsigned int group,
 107                           void *data, size_t data_len)
 108 {
 109         struct kkuc_reg *reg;
 110
 111         if (group > KUC_GRP_MAX) {
 112                 CDEBUG(D_WARNING, "Kernelcomm: bad group %d\n", group);
 113                 return -EINVAL;
 114         }
 115
 116         /* fput in group_rem */
 117         if (!filp)
 118                 return -EBADF;
 119
 120         /* freed in group_rem */
 121         reg = kmalloc(sizeof(*reg) + data_len, 0);
 122         if (!reg)
 123                 return -ENOMEM;
 124
 125         reg->kr_fp = filp;
 126         reg->kr_uid = uid;
 127         memcpy(reg->kr_data, data, data_len);
 128
 129         down_write(&kg_sem);
 130         if (!kkuc_groups[group].next)
 131                 INIT_LIST_HEAD(&kkuc_groups[group]);
 132         list_add(&reg->kr_chain, &kkuc_groups[group]);
 133         up_write(&kg_sem);
 134
 135         CDEBUG(D_KUC, "Added uid=%d fp=%p to group %d\n", uid, filp, group);
 136
 137         return 0;
 138 }
 139 EXPORT_SYMBOL(libcfs_kkuc_group_add);
 140
 141 int libcfs_kkuc_group_rem(int uid, unsigned int group)
 142 {
 143         struct kkuc_reg *reg, *next;
 144
 145         if (!kkuc_groups[group].next)
 146                 return 0;
 147
 148         if (!uid) {
 149                 /* Broadcast a shutdown message */
 150                 struct kuc_hdr lh;
 151
 152                 lh.kuc_magic = KUC_MAGIC;
 153                 lh.kuc_transport = KUC_TRANSPORT_GENERIC;
 154                 lh.kuc_msgtype = KUC_MSG_SHUTDOWN;
 155                 lh.kuc_msglen = sizeof(lh);
 156                 libcfs_kkuc_group_put(group, &lh);
 157         }
 158
 159         down_write(&kg_sem);
 160         list_for_each_entry_safe(reg, next, &kkuc_groups[group], kr_chain) {
 161                 if (!uid || (uid == reg->kr_uid)) {
 162                         list_del(&reg->kr_chain);
 163                         CDEBUG(D_KUC, "Removed uid=%d fp=%p from group %d\n",
 164                                reg->kr_uid, reg->kr_fp, group);
 165                         if (reg->kr_fp)
 166                                 fput(reg->kr_fp);
 167                         kfree(reg);
 168                 }
 169         }
 170         up_write(&kg_sem);
 171
 172         return 0;
 173 }
 174 EXPORT_SYMBOL(libcfs_kkuc_group_rem);
 175
 176 int libcfs_kkuc_group_put(unsigned int group, void *payload)
 177 {
 178         struct kkuc_reg *reg;
 179         int rc = 0;
 180         int one_success = 0;
 181
 182         down_write(&kg_sem);
 183         list_for_each_entry(reg, &kkuc_groups[group], kr_chain) {
 184                 if (reg->kr_fp) {
 185                         rc = libcfs_kkuc_msg_put(reg->kr_fp, payload);
 186                         if (!rc) {
 187                                 one_success = 1;
 188                         } else if (rc == -EPIPE) {
 189                                 fput(reg->kr_fp);
 190                                 reg->kr_fp = NULL;
 191                         }
 192                 }
 193         }
 194         up_write(&kg_sem);
 195
 196         /*
 197          * don't return an error if the message has been delivered
 198          * at least to one agent
 199          */
 200         if (one_success)
 201                 rc = 0;
 202
 203         return rc;
 204 }
 205 EXPORT_SYMBOL(libcfs_kkuc_group_put);
 206
 207 /**
 208  * Calls a callback function for each link of the given kuc group.
 209  * @param group the group to call the function on.
 210  * @param cb_func the function to be called.
 211  * @param cb_arg extra argument to be passed to the callback function.
 212  */
 213 int libcfs_kkuc_group_foreach(unsigned int group, libcfs_kkuc_cb_t cb_func,
 214                               void *cb_arg)
 215 {
 216         struct kkuc_reg *reg;
 217         int rc = 0;
 218
 219         if (group > KUC_GRP_MAX) {
 220                 CDEBUG(D_WARNING, "Kernelcomm: bad group %d\n", group);
 221                 return -EINVAL;
 222         }
 223
 224         /* no link for this group */
 225         if (!kkuc_groups[group].next)
 226                 return 0;
 227
 228         down_read(&kg_sem);
 229         list_for_each_entry(reg, &kkuc_groups[group], kr_chain) {
 230                 if (reg->kr_fp)
 231                         rc = cb_func(reg->kr_data, cb_arg);
 232         }
 233         up_read(&kg_sem);
 234
 235         return rc;
 236 }
 237 EXPORT_SYMBOL(libcfs_kkuc_group_foreach);