2 * Copyright (C) 2006-2009 Red Hat, Inc.
4 * This file is released under the LGPL.
7 #include <linux/kernel.h>
8 #include <linux/module.h>
10 #include <linux/workqueue.h>
11 #include <linux/connector.h>
12 #include <linux/device-mapper.h>
13 #include <linux/dm-log-userspace.h>
15 #include "dm-log-userspace-transfer.h"
17 static uint32_t dm_ulog_seq;
20 * Netlink/Connector is an unreliable protocol. How long should
21 * we wait for a response before assuming it was lost and retrying?
22 * (If we do receive a response after this time, it will be discarded
23 * and the response to the resent request will be waited for.
25 #define DM_ULOG_RETRY_TIMEOUT (15 * HZ)
28 * Pre-allocated space for speed
30 #define DM_ULOG_PREALLOCED_SIZE 512
31 static struct cn_msg *prealloced_cn_msg;
32 static struct dm_ulog_request *prealloced_ulog_tfr;
34 static struct cb_id ulog_cn_id = {
36 .val = CN_VAL_DM_USERSPACE_LOG
39 static DEFINE_MUTEX(dm_ulog_lock);
41 struct receiving_pkg {
42 struct list_head list;
43 struct completion complete;
52 static DEFINE_SPINLOCK(receiving_list_lock);
53 static struct list_head receiving_list;
55 static int dm_ulog_sendto_server(struct dm_ulog_request *tfr)
58 struct cn_msg *msg = prealloced_cn_msg;
60 memset(msg, 0, sizeof(struct cn_msg));
62 msg->id.idx = ulog_cn_id.idx;
63 msg->id.val = ulog_cn_id.val;
66 msg->len = sizeof(struct dm_ulog_request) + tfr->data_size;
68 r = cn_netlink_send(msg, 0, gfp_any());
74 * Parameters for this function can be either msg or tfr, but not
75 * both. This function fills in the reply for a waiting request.
76 * If just msg is given, then the reply is simply an ACK from userspace
77 * that the request was received.
79 * Returns: 0 on success, -ENOENT on failure
81 static int fill_pkg(struct cn_msg *msg, struct dm_ulog_request *tfr)
83 uint32_t rtn_seq = (msg) ? msg->seq : (tfr) ? tfr->seq : 0;
84 struct receiving_pkg *pkg;
87 * The 'receiving_pkg' entries in this list are statically
88 * allocated on the stack in 'dm_consult_userspace'.
89 * Each process that is waiting for a reply from the user
90 * space server will have an entry in this list.
92 * We are safe to do it this way because the stack space
93 * is unique to each process, but still addressable by
96 list_for_each_entry(pkg, &receiving_list, list) {
97 if (rtn_seq != pkg->seq)
101 pkg->error = -msg->ack;
103 * If we are trying again, we will need to know our
104 * storage capacity. Otherwise, along with the
105 * error code, we make explicit that we have no data.
107 if (pkg->error != -EAGAIN)
108 *(pkg->data_size) = 0;
109 } else if (tfr->data_size > *(pkg->data_size)) {
110 DMERR("Insufficient space to receive package [%u] "
111 "(%u vs %zu)", tfr->request_type,
112 tfr->data_size, *(pkg->data_size));
114 *(pkg->data_size) = 0;
115 pkg->error = -ENOSPC;
117 pkg->error = tfr->error;
118 memcpy(pkg->data, tfr->data, tfr->data_size);
119 *(pkg->data_size) = tfr->data_size;
121 complete(&pkg->complete);
129 * This is the connector callback that delivers data
130 * that was sent from userspace.
132 static void cn_ulog_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
134 struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
136 if (!cap_raised(nsp->eff_cap, CAP_SYS_ADMIN))
139 spin_lock(&receiving_list_lock);
142 else if (msg->len < sizeof(*tfr))
143 DMERR("Incomplete message received (expected %u, got %u): [%u]",
144 (unsigned)sizeof(*tfr), msg->len, msg->seq);
147 spin_unlock(&receiving_list_lock);
151 * dm_consult_userspace
152 * @uuid: log's universal unique identifier (must be DM_UUID_LEN in size)
153 * @luid: log's local unique identifier
154 * @request_type: found in include/linux/dm-log-userspace.h
155 * @data: data to tx to the server
156 * @data_size: size of data in bytes
157 * @rdata: place to put return data from server
158 * @rdata_size: value-result (amount of space given/amount of space used)
160 * rdata_size is undefined on failure.
162 * Memory used to communicate with userspace is zero'ed
163 * before populating to ensure that no unwanted bits leak
164 * from kernel space to user-space. All userspace log communications
165 * between kernel and user space go through this function.
167 * Returns: 0 on success, -EXXX on failure
169 int dm_consult_userspace(const char *uuid, uint64_t luid, int request_type,
170 char *data, size_t data_size,
171 char *rdata, size_t *rdata_size)
176 sizeof(struct dm_ulog_request *) + sizeof(struct cn_msg);
177 struct dm_ulog_request *tfr = prealloced_ulog_tfr;
178 struct receiving_pkg pkg;
180 if (data_size > (DM_ULOG_PREALLOCED_SIZE - overhead_size)) {
181 DMINFO("Size of tfr exceeds preallocated size");
189 * We serialize the sending of requests so we can
190 * use the preallocated space.
192 mutex_lock(&dm_ulog_lock);
194 memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - overhead_size);
195 memcpy(tfr->uuid, uuid, DM_UUID_LEN);
197 tfr->seq = dm_ulog_seq++;
200 * Must be valid request type (all other bits set to
201 * zero). This reserves other bits for possible future
204 tfr->request_type = request_type & DM_ULOG_REQUEST_MASK;
206 tfr->data_size = data_size;
207 if (data && data_size)
208 memcpy(tfr->data, data, data_size);
210 memset(&pkg, 0, sizeof(pkg));
211 init_completion(&pkg.complete);
213 pkg.data_size = rdata_size;
215 spin_lock(&receiving_list_lock);
216 list_add(&(pkg.list), &receiving_list);
217 spin_unlock(&receiving_list_lock);
219 r = dm_ulog_sendto_server(tfr);
221 mutex_unlock(&dm_ulog_lock);
224 DMERR("Unable to send log request [%u] to userspace: %d",
226 spin_lock(&receiving_list_lock);
227 list_del_init(&(pkg.list));
228 spin_unlock(&receiving_list_lock);
233 r = wait_for_completion_timeout(&(pkg.complete), DM_ULOG_RETRY_TIMEOUT);
234 spin_lock(&receiving_list_lock);
235 list_del_init(&(pkg.list));
236 spin_unlock(&receiving_list_lock);
238 DMWARN("[%s] Request timed out: [%u/%u] - retrying",
240 (uuid + (strlen(uuid) - 8)) : (uuid),
241 request_type, pkg.seq);
253 int dm_ulog_tfr_init(void)
258 INIT_LIST_HEAD(&receiving_list);
260 prealloced = kmalloc(DM_ULOG_PREALLOCED_SIZE, GFP_KERNEL);
264 prealloced_cn_msg = prealloced;
265 prealloced_ulog_tfr = prealloced + sizeof(struct cn_msg);
267 r = cn_add_callback(&ulog_cn_id, "dmlogusr", cn_ulog_callback);
269 cn_del_callback(&ulog_cn_id);
276 void dm_ulog_tfr_exit(void)
278 cn_del_callback(&ulog_cn_id);
279 kfree(prealloced_cn_msg);