1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/*
* Copyright (c) 2019, Mellanox Technologies. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/timerfd.h>
#include <sys/inotify.h>
#include <sys/sysmacros.h>
#include <poll.h>
#include <util/util.h>
#include <config.h>
static int open_cdev_internal(const char *path, dev_t cdev)
{
struct stat st;
int fd;
fd = open(path, O_RDWR | O_CLOEXEC);
if (fd == -1)
return -1;
if (fstat(fd, &st) || !S_ISCHR(st.st_mode) ||
(cdev != 0 && st.st_rdev != cdev)) {
close(fd);
return -1;
}
return fd;
}
/*
* In case the cdev was not exactly where we should be, use this more
* elaborate approach to find it. This is designed to resolve a race with
* module autoloading where udev is concurrently creately the cdev as we are
* looking for it. udev has 5 seconds to create the link or we fail.
*
* Modern userspace and kernels create the /dev/infiniband/X synchronously via
* devtmpfs before returning from the netlink query, so they should never use
* this path.
*/
static int open_cdev_robust(const char *devname_hint, dev_t cdev)
{
struct itimerspec ts = { .it_value = { .tv_sec = 5 } };
uint64_t buf[sizeof(struct inotify_event) * 16 / sizeof(uint64_t)];
struct pollfd fds[2];
char *devpath;
int res = -1;
int ifd;
int tfd;
/*
* This assumes that udev is being used and is creating the /dev/char/
* symlinks.
*/
if (asprintf(&devpath, "/dev/char/%u:%u", major(cdev), minor(cdev)) < 0)
return -1;
/* Use inotify to speed up the resolution time. */
ifd = inotify_init1(IN_CLOEXEC | IN_NONBLOCK);
if (ifd == -1)
goto err_mem;
if (inotify_add_watch(ifd, "/dev/char/", IN_CREATE) == -1)
goto err_inotify;
/* Timerfd is simpler than working with relative time outs */
tfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);
if (tfd == -1)
goto err_inotify;
if (timerfd_settime(tfd, 0, &ts, NULL) == -1)
goto out_timer;
res = open_cdev_internal(devpath, cdev);
if (res != -1)
goto out_timer;
fds[0].fd = ifd;
fds[0].events = POLLIN;
fds[1].fd = tfd;
fds[1].events = POLLIN;
while (poll(fds, 2, -1) > 0) {
res = open_cdev_internal(devpath, cdev);
if (res != -1)
goto out_timer;
if (fds[0].revents) {
if (read(ifd, buf, sizeof(buf)) == -1)
goto out_timer;
}
if (fds[1].revents)
goto out_timer;
}
out_timer:
close(tfd);
err_inotify:
close(ifd);
err_mem:
free(devpath);
return res;
}
int open_cdev(const char *devname_hint, dev_t cdev)
{
char *devpath;
int fd;
if (asprintf(&devpath, RDMA_CDEV_DIR "/%s", devname_hint) < 0)
return -1;
fd = open_cdev_internal(devpath, cdev);
free(devpath);
if (fd == -1 && cdev != 0)
return open_cdev_robust(devname_hint, cdev);
return fd;
}
|
