X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fcompat%2Fcompat-epoll.c;h=25c9955045b3bb09435beea959d891c67f1c77a4;hp=e58497232a130c002940cd1ffeb5b879129d47b7;hb=13021756b87be3b7e41083f607fa0a54792d153a;hpb=d14d33bf091e72b23b1f90ea18a0a01bed098b76

diff --git a/src/common/compat/compat-epoll.c b/src/common/compat/compat-epoll.c
index e58497232..25c995504 100644
--- a/src/common/compat/compat-epoll.c
+++ b/src/common/compat/compat-epoll.c
@@ -16,6 +16,7 @@
  */
 
 #define _GNU_SOURCE
+#include <assert.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <stdlib.h>
@@ -26,11 +27,39 @@
 
 #include <common/error.h>
 #include <common/defaults.h>
+#include <common/macros.h>
+#include <common/utils.h>
 
 #include "poll.h"
 
 unsigned int poll_max_size;
 
+/*
+ * Resize the epoll events structure of the new size.
+ *
+ * Return 0 on success or else -1 with the current events pointer untouched.
+ */
+static int resize_poll_event(struct lttng_poll_event *events,
+		uint32_t new_size)
+{
+	struct epoll_event *ptr;
+
+	assert(events);
+
+	ptr = realloc(events->events, new_size * sizeof(*ptr));
+	if (ptr == NULL) {
+		PERROR("realloc epoll add");
+		goto error;
+	}
+	events->events = ptr;
+	events->alloc_size = new_size;
+
+	return 0;
+
+error:
+	return -1;
+}
+
 /*
  * Create epoll set and allocate returned events structure.
  */
@@ -43,7 +72,7 @@ int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
 	}
 
 	/* Don't bust the limit here */
-	if (size > poll_max_size) {
+	if (size > poll_max_size && poll_max_size != 0) {
 		size = poll_max_size;
 	}
 
@@ -63,7 +92,7 @@ int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
 		goto error_close;
 	}
 
-	events->events_size = size;
+	events->alloc_size = events->init_size = size;
 	events->nb_fd = 0;
 
 	return 0;
@@ -82,8 +111,8 @@ error:
  */
 int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events)
 {
-	int ret, new_size;
-	struct epoll_event ev, *ptr;
+	int ret;
+	struct epoll_event ev;
 
 	if (events == NULL || events->events == NULL || fd < 0) {
 		ERR("Bad compat epoll add arguments");
@@ -112,17 +141,6 @@ int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_event
 
 	events->nb_fd++;
 
-	if (events->nb_fd >= events->events_size) {
-		new_size = 2 * events->events_size;
-		ptr = realloc(events->events, new_size * sizeof(struct epoll_event));
-		if (ptr == NULL) {
-			PERROR("realloc epoll add");
-			goto error;
-		}
-		events->events = ptr;
-		events->events_size = new_size;
-	}
-
 end:
 	return 0;
 
@@ -153,8 +171,6 @@ int compat_epoll_del(struct lttng_poll_event *events, int fd)
 			PERROR("epoll_ctl DEL fatal");
 			goto error;
 		}
-		PERROR("epoll_ctl del");
-		goto error;
 	}
 
 	events->nb_fd--;
@@ -172,13 +188,43 @@ error:
 int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
 {
 	int ret;
+	uint32_t new_size;
 
-	if (events == NULL || events->events == NULL ||
-			events->events_size < events->nb_fd) {
+	if (events == NULL || events->events == NULL) {
 		ERR("Wrong arguments in compat_epoll_wait");
 		goto error;
 	}
 
+	/*
+	 * 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) {
+		ret = resize_poll_event(events, new_size);
+		if (ret < 0) {
+			/* ENOMEM problem at this point. */
+			goto error;
+		}
+	}
+
 	do {
 		ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout);
 	} while (ret == -1 && errno == EINTR);
@@ -188,6 +234,10 @@ int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
 		goto error;
 	}
 
+	/*
+	 * Since the returned events are set sequentially in the "events" structure
+	 * we only need to return the epoll_wait value and iterate over it.
+	 */
 	return ret;
 
 error:
@@ -200,6 +250,7 @@ error:
 void compat_epoll_set_max_size(void)
 {
 	int ret, fd;
+	ssize_t size_ret;
 	char buf[64];
 
 	poll_max_size = DEFAULT_POLL_SIZE;
@@ -209,14 +260,19 @@ void compat_epoll_set_max_size(void)
 		return;
 	}
 
-	ret = read(fd, buf, sizeof(buf));
-	if (ret < 0) {
+	size_ret = lttng_read(fd, buf, sizeof(buf));
+	/*
+	 * Allow reading a file smaller than buf, but keep space for
+	 * final \0.
+	 */
+	if (size_ret < 0 || size_ret >= sizeof(buf)) {
 		PERROR("read set max size");
 		goto error;
 	}
+	buf[size_ret] = '\0';
 
 	poll_max_size = atoi(buf);
-	if (poll_max_size <= 0) {
+	if (poll_max_size == 0) {
 		/* Extra precaution */
 		poll_max_size = DEFAULT_POLL_SIZE;
 	}