1.\" Copyright (c) 1999 Chris Costello 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd October 7, 2010 28.Dt MAKE_DEV 9 29.Os 30.Sh NAME 31.Nm make_dev , 32.Nm make_dev_cred , 33.Nm make_dev_credf , 34.Nm make_dev_alias , 35.Nm destroy_dev , 36.Nm destroy_dev_sched , 37.Nm destroy_dev_sched_cb , 38.Nm destroy_dev_drain , 39.Nm dev_depends 40.Nd manage 41.Vt cdev Ns 's 42and DEVFS registration for devices 43.Sh SYNOPSIS 44.In sys/param.h 45.In sys/conf.h 46.Ft struct cdev * 47.Fn make_dev "struct cdevsw *cdevsw" "int unit" "uid_t uid" "gid_t gid" "int perms" "const char *fmt" ... 48.Ft struct cdev * 49.Fn make_dev_cred "struct cdevsw *cdevsw" "int unit" "struct ucred *cr" "uid_t uid" "gid_t gid" "int perms" "const char *fmt" ... 50.Ft struct cdev * 51.Fn make_dev_credf "int flags" "struct cdevsw *cdevsw" "int unit" "struct ucred *cr" "uid_t uid" "gid_t gid" "int perms" "const char *fmt" ... 52.Ft struct cdev * 53.Fn make_dev_alias "struct cdev *pdev" "const char *fmt" ... 54.Ft void 55.Fn destroy_dev "struct cdev *dev" 56.Ft void 57.Fn destroy_dev_sched "struct cdev *dev" 58.Ft void 59.Fn destroy_dev_sched_cb "struct cdev *dev" "void (*cb)(void *)" "void *arg" 60.Ft void 61.Fn destroy_dev_drain "struct cdevsw *csw" 62.Ft void 63.Fn dev_depends "struct cdev *pdev" "struct cdev *cdev" 64.Sh DESCRIPTION 65The 66.Fn make_dev_credf 67function creates a 68.Fa cdev 69structure for a new device. 70It also notifies 71.Xr devfs 5 72of the presence of the new device, that causes corresponding nodes 73to be created. 74Besides this, a 75.Xr devctl 4 76notification is sent. 77The device will be owned by 78.Va uid , 79with the group ownership as 80.Va gid . 81The name is the expansion of 82.Va fmt 83and following arguments as 84.Xr printf 9 85would print it. 86The name determines its path under 87.Pa /dev 88or other 89.Xr devfs 5 90mount point and may contain slash 91.Ql / 92characters to denote subdirectories. 93The permissions of the file specified in 94.Va perms 95are defined in 96.In sys/stat.h : 97.Pp 98.Bd -literal -offset indent -compact 99#define S_IRWXU 0000700 /* RWX mask for owner */ 100#define S_IRUSR 0000400 /* R for owner */ 101#define S_IWUSR 0000200 /* W for owner */ 102#define S_IXUSR 0000100 /* X for owner */ 103 104#define S_IRWXG 0000070 /* RWX mask for group */ 105#define S_IRGRP 0000040 /* R for group */ 106#define S_IWGRP 0000020 /* W for group */ 107#define S_IXGRP 0000010 /* X for group */ 108 109#define S_IRWXO 0000007 /* RWX mask for other */ 110#define S_IROTH 0000004 /* R for other */ 111#define S_IWOTH 0000002 /* W for other */ 112#define S_IXOTH 0000001 /* X for other */ 113 114#define S_ISUID 0004000 /* set user id on execution */ 115#define S_ISGID 0002000 /* set group id on execution */ 116#define S_ISVTX 0001000 /* sticky bit */ 117#ifndef _POSIX_SOURCE 118#define S_ISTXT 0001000 119#endif 120.Ed 121.Pp 122The 123.Va cr 124argument specifies credentials that will be stored in the 125.Fa si_cred 126member of the initialized 127.Fa struct cdev . 128The 129.Va flags 130argument alters the operation of 131.Fn make_dev_credf . 132The following values are currently accepted: 133.Pp 134.Bl -tag -width "MAKEDEV_CHECKNAME" -compact -offset indent 135.It MAKEDEV_REF 136reference the created device 137.It MAKEDEV_NOWAIT 138do not sleep, may return NULL 139.It MAKEDEV_WAITOK 140allow the function to sleep to satisfy malloc 141.It MAKEDEV_ETERNAL 142created device will be never destroyed 143.It MAKEDEV_CHECKNAME 144return NULL if the device name is invalid or already exists 145.El 146.Pp 147The 148.Dv MAKEDEV_WAITOK 149flag is assumed if none of 150.Dv MAKEDEV_WAITOK , 151.Dv MAKEDEV_NOWAIT 152is specified. 153.Pp 154The 155.Xr dev_clone 9 156event handler shall specify 157.Dv MAKEDEV_REF 158flag when creating a device in response to lookup, to avoid race where 159the device created is destroyed immediately after 160.Xr devfs_lookup 9 161drops his reference to cdev. 162.Pp 163The 164.Dv MAKEDEV_ETERNAL 165flag allows the kernel to not acquire some locks when translating system 166calls into the cdevsw methods calls. 167It is responsibility of the driver author to make sure that 168.Fn destroy_dev 169is never called on the returned cdev. 170For the convenience, use the 171.Dv MAKEDEV_ETERNAL_KLD 172flag for the code that can be compiled into kernel or loaded 173(and unloaded) as loadable module. 174.Pp 175A panic will occur if the MAKEDEV_CHECKNAME flag is not specified 176and the device name is invalid or already exists. 177.Pp 178The 179.Fn make_dev_cred 180function is equivalent to the call 181.Bd -literal -offset indent 182make_dev_credf(0, cdevsw, unit, cr, uid, gid, perms, fmt, ...); 183.Ed 184.Pp 185The 186.Fn make_dev 187function call is the same as 188.Bd -literal -offset indent 189make_dev_credf(0, cdevsw, unit, NULL, uid, gid, perms, fmt, ...); 190.Ed 191.Pp 192The 193.Fn make_dev_alias 194function takes the returned 195.Ft cdev 196from 197.Fn make_dev 198and makes another (aliased) name for this device. 199It is an error to call 200.Fn make_dev_alias 201prior to calling 202.Fn make_dev . 203.Pp 204The 205.Fa cdev 206returned by 207.Fn make_dev 208and 209.Fn make_dev_alias 210has two fields, 211.Fa si_drv1 212and 213.Fa si_drv2 , 214that are available to store state. 215Both fields are of type 216.Ft void * . 217These are designed to replace the 218.Fa unit 219argument to 220.Fn make_dev , 221which can be obtained with 222.Fn dev2unit . 223.Pp 224The 225.Fn destroy_dev 226function takes the returned 227.Fa cdev 228from 229.Fn make_dev 230and destroys the registration for that device. 231The notification is sent to 232.Xr devctl 4 233about the destruction event. 234Do not call 235.Fn destroy_dev 236on devices that were created with 237.Fn make_dev_alias . 238.Pp 239The 240.Fn dev_depends 241function establishes a parent-child relationship between two devices. 242The net effect is that a 243.Fn destroy_dev 244of the parent device will also result in the destruction of the 245child device(s), 246if any exist. 247A device may simultaneously be a parent and a child, 248so it is possible to build a complete hierarchy. 249.Pp 250The 251.Fn destroy_dev_sched_cb 252function schedules execution of the 253.Fn destroy_dev 254for the specified 255.Fa cdev 256in the safe context. 257After 258.Fn destroy_dev 259is finished, and if the supplied 260.Fa cb 261is not NULL, the callback 262.Fa cb 263is called, with argument 264.Fa arg . 265The 266.Fn destroy_dev_sched 267function is the same as 268.Bd -literal -offset indent 269destroy_dev_sched_cb(cdev, NULL, NULL); 270.Ed 271.Pp 272The 273.Fn d_close 274driver method cannot call 275.Fn destroy_dev 276directly. Doing so causes deadlock when 277.Fn destroy_dev 278waits for all threads to leave the driver methods. 279Also, because 280.Fn destroy_dev 281sleeps, no non-sleepable locks may be held over the call. 282The 283.Fn destroy_dev_sched 284family of functions overcome these issues. 285.Pp 286The device driver may call the 287.Fn destroy_dev_drain 288function to wait until all devices that have supplied 289.Fa csw 290as cdevsw, are destroyed. This is useful when driver knows that 291.Fn destroy_dev_sched 292is called for all instantiated devices, but need to postpone module 293unload until 294.Fn destroy_dev 295is actually finished for all of them. 296.Pp 297.Sh SEE ALSO 298.Xr devctl 4 , 299.Xr destroy_dev_drain 9 , 300.Xr dev_clone 9 , 301.Xr devfs 5 302.Sh HISTORY 303The 304.Fn make_dev 305and 306.Fn destroy_dev 307functions first appeared in 308.Fx 4.0 . 309The function 310.Fn make_dev_alias 311first appeared in 312.Fx 4.1 . 313The function 314.Fn dev_depends 315first appeared in 316.Fx 5.0 . 317The functions 318.Fn make_dev_credf , 319.Fn destroy_dev_sched , 320.Fn destroy_dev_sched_cb 321first appeared in 322.Fx 7.0 . 323