2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
23 #include <sys/types.h>
27 #include <common/error.h>
28 #include <common/defaults.h>
29 #include <common/macros.h>
30 #include <common/utils.h>
34 unsigned int poll_max_size
;
37 * Resize the epoll events structure of the new size.
39 * Return 0 on success or else -1 with the current events pointer untouched.
41 static int resize_poll_event(struct lttng_poll_event
*events
,
44 struct epoll_event
*ptr
;
48 ptr
= realloc(events
->events
, new_size
* sizeof(*ptr
));
50 PERROR("realloc epoll add");
53 if (new_size
> events
->alloc_size
) {
54 /* Zero newly allocated memory */
55 memset(ptr
+ events
->alloc_size
, 0,
56 (new_size
- events
->alloc_size
) * sizeof(*ptr
));
59 events
->alloc_size
= new_size
;
68 * Create epoll set and allocate returned events structure.
70 int compat_epoll_create(struct lttng_poll_event
*events
, int size
, int flags
)
74 if (events
== NULL
|| size
<= 0) {
79 if (lttng_poll_set_max_size()) {
84 /* Don't bust the limit here */
85 if (size
> poll_max_size
) {
89 ret
= compat_glibc_epoll_create(size
, flags
);
91 /* At this point, every error is fatal */
92 PERROR("epoll_create1");
98 /* This *must* be freed by using lttng_poll_free() */
99 events
->events
= zmalloc(size
* sizeof(struct epoll_event
));
100 if (events
->events
== NULL
) {
101 PERROR("zmalloc epoll set");
105 events
->alloc_size
= events
->init_size
= size
;
111 ret
= close(events
->epfd
);
120 * Add a fd to the epoll set with requesting events.
122 int compat_epoll_add(struct lttng_poll_event
*events
, int fd
, uint32_t req_events
)
125 struct epoll_event ev
;
127 if (events
== NULL
|| events
->events
== NULL
|| fd
< 0) {
128 ERR("Bad compat epoll add arguments");
133 * Zero struct epoll_event to ensure all representations of its
136 memset(&ev
, 0, sizeof(ev
));
137 ev
.events
= req_events
;
140 ret
= epoll_ctl(events
->epfd
, EPOLL_CTL_ADD
, fd
, &ev
);
144 /* If exist, it's OK. */
148 /* Print PERROR and goto end not failing. Show must go on. */
149 PERROR("epoll_ctl ADD");
152 PERROR("epoll_ctl ADD fatal");
167 * Remove a fd from the epoll set.
169 int compat_epoll_del(struct lttng_poll_event
*events
, int fd
)
173 if (events
== NULL
|| fd
< 0 || events
->nb_fd
== 0) {
177 ret
= epoll_ctl(events
->epfd
, EPOLL_CTL_DEL
, fd
, NULL
);
182 /* Print PERROR and goto end not failing. Show must go on. */
183 PERROR("epoll_ctl DEL");
186 PERROR("epoll_ctl DEL fatal");
201 * Set an fd's events.
203 int compat_epoll_mod(struct lttng_poll_event
*events
, int fd
, uint32_t req_events
)
206 struct epoll_event ev
;
208 if (events
== NULL
|| fd
< 0 || events
->nb_fd
== 0) {
213 * Zero struct epoll_event to ensure all representations of its
216 memset(&ev
, 0, sizeof(ev
));
217 ev
.events
= req_events
;
220 ret
= epoll_ctl(events
->epfd
, EPOLL_CTL_MOD
, fd
, &ev
);
225 /* Print PERROR and goto end not failing. Show must go on. */
226 PERROR("epoll_ctl MOD");
229 PERROR("epoll_ctl MOD fatal");
242 * Wait on epoll set. This is a blocking call of timeout value.
244 int compat_epoll_wait(struct lttng_poll_event
*events
, int timeout
)
249 if (events
== NULL
|| events
->events
== NULL
) {
250 ERR("Wrong arguments in compat_epoll_wait");
254 if (events
->nb_fd
== 0) {
260 * Resize if needed before waiting. We could either expand the array or
261 * shrink it down. It's important to note that after this step, we are
262 * ensured that the events argument of the epoll_wait call will be large
263 * enough to hold every possible returned events.
265 new_size
= 1U << utils_get_count_order_u32(events
->nb_fd
);
266 if (new_size
!= events
->alloc_size
&& new_size
>= events
->init_size
) {
267 ret
= resize_poll_event(events
, new_size
);
269 /* ENOMEM problem at this point. */
275 ret
= epoll_wait(events
->epfd
, events
->events
, events
->nb_fd
, timeout
);
276 } while (ret
== -1 && errno
== EINTR
);
278 /* At this point, every error is fatal */
279 PERROR("epoll_wait");
284 * Since the returned events are set sequentially in the "events" structure
285 * we only need to return the epoll_wait value and iterate over it.
294 * Setup poll set maximum size.
296 int compat_epoll_set_max_size(void)
298 int ret
, fd
, retval
= 0;
302 fd
= open(COMPAT_EPOLL_PROC_PATH
, O_RDONLY
);
305 * Failing on opening [1] is not an error per see. [1] was
306 * introduced in Linux 2.6.28 but epoll is available since
307 * 2.5.44. Hence, goto end and set a default value without
308 * setting an error return value.
310 * [1] /proc/sys/fs/epoll/max_user_watches
316 size_ret
= lttng_read(fd
, buf
, sizeof(buf
));
318 * Allow reading a file smaller than buf, but keep space for
321 if (size_ret
< 0 || size_ret
>= sizeof(buf
)) {
322 PERROR("read set max size");
326 buf
[size_ret
] = '\0';
327 poll_max_size
= atoi(buf
);
334 if (!poll_max_size
) {
335 poll_max_size
= DEFAULT_POLL_SIZE
;
337 DBG("epoll set max size is %d", poll_max_size
);
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