/*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
*
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
-#define _GNU_SOURCE
+#define _LGPL_SOURCE
#include <assert.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
-#include <config.h>
+#include <stdbool.h>
#include <common/error.h>
#include <common/defaults.h>
#include "poll.h"
-unsigned int poll_max_size;
+/*
+ * Maximum number of fd we can monitor.
+ *
+ * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
+ * be used for the maximum size of the poll set. If this interface is not
+ * available, according to the manpage, the max_user_watches value is 1/25 (4%)
+ * of the available low memory divided by the registration cost in bytes which
+ * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
+ *
+ */
+static unsigned int poll_max_size;
/*
* Resize the epoll events structure of the new size.
/*
* Create epoll set and allocate returned events structure.
*/
+LTTNG_HIDDEN
int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
{
int ret;
goto error;
}
+ if (!poll_max_size) {
+ if (lttng_poll_set_max_size()) {
+ goto error;
+ }
+ }
+
/* Don't bust the limit here */
- if (size > poll_max_size && poll_max_size != 0) {
+ if (size > poll_max_size) {
size = poll_max_size;
}
/*
* Add a fd to the epoll set with requesting events.
*/
+LTTNG_HIDDEN
int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events)
{
int ret;
/*
* Remove a fd from the epoll set.
*/
+LTTNG_HIDDEN
int compat_epoll_del(struct lttng_poll_event *events, int fd)
{
int ret;
- if (events == NULL || fd < 0) {
+ if (events == NULL || fd < 0 || events->nb_fd == 0) {
goto error;
}
return -1;
}
+/*
+ * Set an fd's events.
+ */
+LTTNG_HIDDEN
+int compat_epoll_mod(struct lttng_poll_event *events, int fd, uint32_t req_events)
+{
+ int ret;
+ struct epoll_event ev;
+
+ if (events == NULL || fd < 0 || events->nb_fd == 0) {
+ goto error;
+ }
+
+ /*
+ * Zero struct epoll_event to ensure all representations of its
+ * union are zeroed.
+ */
+ memset(&ev, 0, sizeof(ev));
+ ev.events = req_events;
+ ev.data.fd = fd;
+
+ ret = epoll_ctl(events->epfd, EPOLL_CTL_MOD, fd, &ev);
+ if (ret < 0) {
+ switch (errno) {
+ case ENOENT:
+ case EPERM:
+ /* Print PERROR and goto end not failing. Show must go on. */
+ PERROR("epoll_ctl MOD");
+ goto end;
+ default:
+ PERROR("epoll_ctl MOD fatal");
+ goto error;
+ }
+ }
+
+end:
+ return 0;
+
+error:
+ return -1;
+}
+
/*
* Wait on epoll set. This is a blocking call of timeout value.
*/
-int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
+LTTNG_HIDDEN
+int compat_epoll_wait(struct lttng_poll_event *events, int timeout,
+ bool interruptible)
{
int ret;
uint32_t new_size;
goto error;
}
+ if (events->nb_fd == 0) {
+ errno = EINVAL;
+ return -1;
+ }
+
/*
* Resize if needed before waiting. We could either expand the array or
* shrink it down. It's important to note that after this step, we are
* ensured that the events argument of the epoll_wait call will be large
* enough to hold every possible returned events.
*/
- if (events->nb_fd > events->alloc_size) {
- /* Expand if the nb_fd is higher than the actual size. */
- new_size = max_t(uint32_t,
- 1U << utils_get_count_order_u32(events->nb_fd),
- events->alloc_size << 1UL);
- } else if ((events->nb_fd << 1UL) <= events->alloc_size &&
- events->nb_fd >= events->init_size) {
- /* Shrink if nb_fd multiplied by two is <= than the actual size. */
- new_size = max_t(uint32_t,
- utils_get_count_order_u32(events->nb_fd) >> 1U,
- events->alloc_size >> 1U);
- } else {
- /* Indicate that we don't want to resize. */
- new_size = 0;
- }
-
- if (new_size) {
+ new_size = 1U << utils_get_count_order_u32(events->nb_fd);
+ if (new_size != events->alloc_size && new_size >= events->init_size) {
ret = resize_poll_event(events, new_size);
if (ret < 0) {
/* ENOMEM problem at this point. */
do {
ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout);
- } while (ret == -1 && errno == EINTR);
+ } while (!interruptible && ret == -1 && errno == EINTR);
if (ret < 0) {
- /* At this point, every error is fatal */
- PERROR("epoll_wait");
+ if (errno != EINTR) {
+ PERROR("epoll_wait");
+ }
goto error;
}
/*
* Setup poll set maximum size.
*/
-void compat_epoll_set_max_size(void)
+LTTNG_HIDDEN
+int compat_epoll_set_max_size(void)
{
- int ret, fd;
+ int ret, fd, retval = 0;
ssize_t size_ret;
char buf[64];
- poll_max_size = DEFAULT_POLL_SIZE;
-
fd = open(COMPAT_EPOLL_PROC_PATH, O_RDONLY);
if (fd < 0) {
- return;
+ /*
+ * Failing on opening [1] is not an error per see. [1] was
+ * introduced in Linux 2.6.28 but epoll is available since
+ * 2.5.44. Hence, goto end and set a default value without
+ * setting an error return value.
+ *
+ * [1] /proc/sys/fs/epoll/max_user_watches
+ */
+ retval = 0;
+ goto end;
}
size_ret = lttng_read(fd, buf, sizeof(buf));
*/
if (size_ret < 0 || size_ret >= sizeof(buf)) {
PERROR("read set max size");
- goto error;
+ retval = -1;
+ goto end_read;
}
buf[size_ret] = '\0';
-
poll_max_size = atoi(buf);
- if (poll_max_size == 0) {
- /* Extra precaution */
- poll_max_size = DEFAULT_POLL_SIZE;
- }
-
- DBG("epoll set max size is %d", poll_max_size);
-
-error:
+end_read:
ret = close(fd);
if (ret) {
PERROR("close");
}
+end:
+ if (!poll_max_size) {
+ poll_max_size = DEFAULT_POLL_SIZE;
+ }
+ DBG("epoll set max size is %d", poll_max_size);
+ return retval;
}
projects / lttng-tools.git / blobdiff