1 /* $NetBSD: xenbus_client.c,v 1.17 2020/04/07 15:16:52 jdolecek Exp $ */ 2 /****************************************************************************** 3 * Client-facing interface for the Xenbus driver. In other words, the 4 * interface between the Xenbus and the device-specific code, be it the 5 * frontend or the backend of that driver. 6 * 7 * Copyright (C) 2005 XenSource Ltd 8 * 9 * This file may be distributed separately from the Linux kernel, or 10 * incorporated into other software packages, subject to the following license: 11 * 12 * Permission is hereby granted, free of charge, to any person obtaining a copy 13 * of this source file (the "Software"), to deal in the Software without 14 * restriction, including without limitation the rights to use, copy, modify, 15 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 16 * and to permit persons to whom the Software is furnished to do so, subject to 17 * the following conditions: 18 * 19 * The above copyright notice and this permission notice shall be included in 20 * all copies or substantial portions of the Software. 21 * 22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 28 * IN THE SOFTWARE. 29 */ 30 31 #include <sys/cdefs.h> 32 __KERNEL_RCSID(0, "$NetBSD: xenbus_client.c,v 1.17 2020/04/07 15:16:52 jdolecek Exp $"); 33 34 #if 0 35 #define DPRINTK(fmt, args...) \ 36 printk("xenbus_client (%s:%d) " fmt ".\n", __func__, __LINE__, ##args) 37 #else 38 #define DPRINTK(fmt, args...) ((void)0) 39 #endif 40 41 #include <sys/types.h> 42 #include <sys/null.h> 43 #include <sys/errno.h> 44 #include <sys/kmem.h> 45 #include <sys/systm.h> 46 47 #include <xen/xen.h> 48 #include <xen/hypervisor.h> 49 #include <xen/evtchn.h> 50 #include <xen/xenbus.h> 51 #include <xen/granttables.h> 52 53 int 54 xenbus_watch_path2(struct xenbus_device *dev, const char *path, 55 const char *path2, struct xenbus_watch *watch, 56 void (*callback)(struct xenbus_watch *, 57 const char **, unsigned int)) 58 { 59 int err; 60 char *state; 61 62 DPRINTK("xenbus_watch_path2 path %s path2 %s\n", path, path2); 63 64 watch->node_sz = strlen(path) + 1 + strlen(path2) + 1; 65 state = kmem_alloc(watch->node_sz, KM_SLEEP); 66 strcpy(state, path); 67 strcat(state, "/"); 68 strcat(state, path2); 69 70 watch->node = state; 71 watch->xbw_callback = callback; 72 73 err = register_xenbus_watch(watch); 74 75 if (err) { 76 watch->node = NULL; 77 watch->node_sz = 0; 78 watch->xbw_callback = NULL; 79 xenbus_dev_fatal(dev, err, "adding watch on %s", state); 80 kmem_free(state, watch->node_sz); 81 } 82 return err; 83 } 84 85 void 86 xenbus_unwatch_path(struct xenbus_watch *watch) 87 { 88 if (watch->node != NULL) { 89 unregister_xenbus_watch(watch); 90 kmem_free(watch->node, watch->node_sz); 91 watch->node = NULL; 92 } 93 } 94 95 int 96 xenbus_switch_state(struct xenbus_device *dev, 97 struct xenbus_transaction *xbt, 98 XenbusState state) 99 { 100 /* We check whether the state is currently set to the given value, and 101 if not, then the state is set. We don't want to unconditionally 102 write the given state, because we don't want to fire watches 103 unnecessarily. Furthermore, if the node has gone, we don't write 104 to it, as the device will be tearing down, and we don't want to 105 resurrect that directory. 106 */ 107 108 u_long current_state; 109 110 int err = xenbus_read_ul(xbt, dev->xbusd_path, "state", 111 ¤t_state, 10); 112 if (err) 113 return 0; 114 115 if ((XenbusState)current_state == state) 116 return 0; 117 118 err = xenbus_printf(xbt, dev->xbusd_path, "state", "%d", state); 119 if (err) { 120 xenbus_dev_fatal(dev, err, "writing new state"); 121 return err; 122 } 123 return 0; 124 } 125 126 /** 127 * Return the path to the error node for the given device, or NULL on failure. 128 * If the value returned is non-NULL, then it is the caller's to kfree. 129 */ 130 static char * 131 error_path(struct xenbus_device *dev, size_t *len) 132 { 133 *len = strlen("error/") + strlen(dev->xbusd_path) + 1; 134 char *path_buffer = kmem_alloc(*len, KM_NOSLEEP); 135 if (path_buffer == NULL) 136 return NULL; 137 138 strcpy(path_buffer, "error/"); 139 strcpy(path_buffer + strlen("error/"), dev->xbusd_path); 140 141 return path_buffer; 142 } 143 144 145 static void 146 _dev_error(struct xenbus_device *dev, int err, const char *fmt, 147 va_list ap) 148 { 149 int ret __diagused; 150 unsigned int len; 151 char *printf_buffer = NULL, *path_buffer = NULL; 152 size_t path_buffer_sz = 0; 153 154 #define PRINTF_BUFFER_SIZE 4096 155 printf_buffer = kmem_alloc(PRINTF_BUFFER_SIZE, KM_NOSLEEP); 156 if (printf_buffer == NULL) 157 goto fail; 158 159 len = snprintf(printf_buffer, PRINTF_BUFFER_SIZE, "%i ", -err); 160 KASSERT(len < PRINTF_BUFFER_SIZE); 161 ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap); 162 KASSERT(len + ret < PRINTF_BUFFER_SIZE); 163 dev->xbusd_has_error = 1; 164 165 path_buffer = error_path(dev, &path_buffer_sz); 166 if (path_buffer == NULL) { 167 printk("xenbus: failed to write error node for %s (%s)\n", 168 dev->xbusd_path, printf_buffer); 169 goto fail; 170 } 171 172 if (xenbus_write(NULL, path_buffer, "error", printf_buffer) != 0) { 173 printk("xenbus: failed to write error node for %s (%s)\n", 174 dev->xbusd_path, printf_buffer); 175 goto fail; 176 } 177 178 fail: 179 if (printf_buffer) 180 kmem_free(printf_buffer, PRINTF_BUFFER_SIZE); 181 if (path_buffer) 182 kmem_free(path_buffer, path_buffer_sz); 183 } 184 185 186 void 187 xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, 188 ...) 189 { 190 va_list ap; 191 192 va_start(ap, fmt); 193 _dev_error(dev, err, fmt, ap); 194 va_end(ap); 195 } 196 197 198 void 199 xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, 200 ...) 201 { 202 va_list ap; 203 204 va_start(ap, fmt); 205 _dev_error(dev, err, fmt, ap); 206 va_end(ap); 207 208 xenbus_switch_state(dev, NULL, XenbusStateClosing); 209 } 210 211 212 int 213 xenbus_grant_ring(struct xenbus_device *dev, paddr_t ring_pa, 214 grant_ref_t *entryp) 215 { 216 int err = xengnt_grant_access(dev->xbusd_otherend_id, ring_pa, 217 0, entryp); 218 if (err != 0) 219 xenbus_dev_fatal(dev, err, "granting access to ring page"); 220 return err; 221 } 222 223 224 int 225 xenbus_alloc_evtchn(struct xenbus_device *dev, int *port) 226 { 227 evtchn_op_t op = { 228 .cmd = EVTCHNOP_alloc_unbound, 229 .u.alloc_unbound = { 230 .dom = DOMID_SELF, 231 .remote_dom = dev->xbusd_otherend_id, 232 .port = 0 233 } 234 }; 235 236 int err = HYPERVISOR_event_channel_op(&op); 237 if (err) 238 xenbus_dev_fatal(dev, err, "allocating event channel"); 239 else 240 *port = op.u.alloc_unbound.port; 241 return err; 242 } 243 244 245 XenbusState 246 xenbus_read_driver_state(const char *path) 247 { 248 u_long result; 249 250 int err = xenbus_read_ul(NULL, path, "state", &result, 10); 251 if (err) 252 result = XenbusStateClosed; 253 254 return result; 255 } 256 257 258 /* 259 * Local variables: 260 * c-file-style: "linux" 261 * indent-tabs-mode: t 262 * c-indent-level: 8 263 * c-basic-offset: 8 264 * tab-width: 8 265 * End: 266 */ 267
Indexes created Mon Sep 22 10:09:38 GMT 2025