X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Fcommon%2Fcompat%2Fcompat-epoll.c;h=6a781c7ae04034f321f974c244df6e43e01e58b3;hb=18710679a8ac57fda5dbd26cf16bb180dce9e286;hp=29bd2f868ed38e1e6253b8841f2326025cb8c644;hpb=6c1c0768320135c6936c371b09731851b508c023;p=lttng-tools.git

diff --git a/src/common/compat/compat-epoll.c b/src/common/compat/compat-epoll.c
index 29bd2f868..6a781c7ae 100644
--- a/src/common/compat/compat-epoll.c
+++ b/src/common/compat/compat-epoll.c
@@ -15,7 +15,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
 #define _LGPL_SOURCE
 #include <assert.h>
 #include <fcntl.h>
@@ -24,7 +23,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#include <config.h>
 
 #include <common/error.h>
 #include <common/defaults.h>
@@ -77,8 +75,14 @@ int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
 		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;
 	}
 
@@ -166,7 +170,7 @@ 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;
 	}
 
@@ -193,6 +197,47 @@ error:
 	return -1;
 }
 
+/*
+ * Set an fd's events.
+ */
+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.
  */
@@ -206,29 +251,19 @@ int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
 		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. */
@@ -258,17 +293,24 @@ error:
 /*
  * Setup poll set maximum size.
  */
-void compat_epoll_set_max_size(void)
+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));
@@ -278,21 +320,20 @@ void compat_epoll_set_max_size(void)
 	 */
 	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;
 }