X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Fcompat%2Fcompat-poll.c;h=499a2762307f61c16023d574fba7aa337c10c6f9;hb=13c4d8aba5eca5f0d70a42661731d2de6bdc02a4;hp=254ce271e71c2f1b9249942e229b5a4b5b7fc82f;hpb=73b4e79ff411b40a1461f9b9fe093cd53115fc6c;p=lttng-tools.git

diff --git a/src/common/compat/compat-poll.c b/src/common/compat/compat-poll.c
index 254ce271e..499a27623 100644
--- a/src/common/compat/compat-poll.c
+++ b/src/common/compat/compat-poll.c
@@ -30,7 +30,14 @@
 
 #include "poll.h"
 
-unsigned int poll_max_size;
+
+/*
+ * Maximum number of fd we can monitor.
+ *
+ * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
+ * getrlimit(2).
+ */
+static unsigned int poll_max_size;
 
 /*
  * Resize the epoll events structure of the new size.
@@ -103,6 +110,7 @@ error:
 /*
  * Create pollfd data structure.
  */
+LTTNG_HIDDEN
 int compat_poll_create(struct lttng_poll_event *events, int size)
 {
 	struct compat_poll_event_array *current, *wait;
@@ -155,6 +163,7 @@ error:
 /*
  * Add fd to pollfd data structure with requested events.
  */
+LTTNG_HIDDEN
 int compat_poll_add(struct lttng_poll_event *events, int fd,
 		uint32_t req_events)
 {
@@ -201,6 +210,7 @@ error:
 /*
  * Modify an fd's events..
  */
+LTTNG_HIDDEN
 int compat_poll_mod(struct lttng_poll_event *events, int fd,
 		uint32_t req_events)
 {
@@ -237,6 +247,7 @@ error:
 /*
  * Remove a fd from the pollfd structure.
  */
+LTTNG_HIDDEN
 int compat_poll_del(struct lttng_poll_event *events, int fd)
 {
 	int i, count = 0, ret;
@@ -291,11 +302,12 @@ error:
 /*
  * Wait on poll() with timeout. Blocking call.
  */
-int compat_poll_wait(struct lttng_poll_event *events, int timeout)
+LTTNG_HIDDEN
+int compat_poll_wait(struct lttng_poll_event *events, int timeout,
+		bool interruptible)
 {
 	int ret, active_fd_count;
-	int idle_pfd_index = 0;
-	size_t i;
+	size_t pos = 0, consecutive_entries = 0, non_idle_pos;
 
 	if (events == NULL || events->current.events == NULL) {
 		ERR("poll wait arguments error");
@@ -320,44 +332,47 @@ int compat_poll_wait(struct lttng_poll_event *events, int timeout)
 
 	do {
 		ret = poll(events->wait.events, events->wait.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("poll wait");
+		if (errno != EINTR) {
+			PERROR("poll wait");
+		}
 		goto error;
 	}
 
 	active_fd_count = ret;
 
 	/*
-	 * Swap all active pollfd structs to the beginning of the
-	 * array to emulate compat-epoll behaviour. This algorithm takes
-	 * advantage of poll's returned value and the burst nature of active
-	 * events on the file descriptors. The while loop guarantees that
-	 * idle_pfd will always point to an idle fd.
+	 * Move all active pollfd structs to the beginning of the
+	 * array to emulate compat-epoll behaviour.
 	 */
 	if (active_fd_count == events->wait.nb_fd) {
 		goto end;
 	}
-	while (idle_pfd_index < active_fd_count &&
-			events->wait.events[idle_pfd_index].revents != 0) {
-		idle_pfd_index++;
-	}
 
-	for (i = idle_pfd_index + 1; idle_pfd_index < active_fd_count;
-			i++) {
-		struct pollfd swap_pfd;
-		struct pollfd *idle_pfd = &events->wait.events[idle_pfd_index];
-		struct pollfd *current_pfd = &events->wait.events[i];
-
-		if (idle_pfd->revents != 0) {
-			swap_pfd = *current_pfd;
-			*current_pfd = *idle_pfd;
-			*idle_pfd = swap_pfd;
-			idle_pfd_index++;
+	while (consecutive_entries != active_fd_count) {
+		struct pollfd *current = &events->wait.events[pos];
+		struct pollfd idle_entry;
+
+		if (current->revents != 0) {
+			consecutive_entries++;
+			pos++;
+			continue;
 		}
-	}
 
+		non_idle_pos = pos;
+
+		/* Look for next non-idle entry. */
+		while (events->wait.events[++non_idle_pos].revents == 0);
+
+		/* Swap idle and non-idle entries. */
+		idle_entry = *current;
+		*current = events->wait.events[non_idle_pos];
+		events->wait.events[non_idle_pos] = idle_entry;
+
+		consecutive_entries++;
+		pos++;
+	}
 end:
 	return ret;
 
@@ -368,6 +383,7 @@ error:
 /*
  * Setup poll set maximum size.
  */
+LTTNG_HIDDEN
 int compat_poll_set_max_size(void)
 {
 	int ret, retval = 0;