X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fconsumer.c;h=ee5575262ec5667d448007a8ab82eec0607e19c9;hp=2604f3d060574c1c7677047fcc16581a5c54818d;hb=04fdd819f0eebfd15a4196a9ca98e826352a9b4f;hpb=9ef70f8738b524b8ea4f266c526de9d5a4fdc29c

diff --git a/src/common/consumer.c b/src/common/consumer.c
index 2604f3d06..ee5575262 100644
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -736,6 +736,20 @@ struct lttng_consumer_local_data *lttng_consumer_create(
 		goto error_poll_pipe;
 	}
 
+	/* set read end of the pipe to non-blocking */
+	ret = fcntl(ctx->consumer_poll_pipe[0], F_SETFL, O_NONBLOCK);
+	if (ret < 0) {
+		perror("fcntl O_NONBLOCK");
+		goto error_poll_fcntl;
+	}
+
+	/* set write end of the pipe to non-blocking */
+	ret = fcntl(ctx->consumer_poll_pipe[1], F_SETFL, O_NONBLOCK);
+	if (ret < 0) {
+		perror("fcntl O_NONBLOCK");
+		goto error_poll_fcntl;
+	}
+
 	ret = pipe(ctx->consumer_should_quit);
 	if (ret < 0) {
 		perror("Error creating recv pipe");
@@ -760,6 +774,7 @@ error_thread_pipe:
 			PERROR("close");
 		}
 	}
+error_poll_fcntl:
 error_quit_pipe:
 	for (i = 0; i < 2; i++) {
 		int err;
@@ -933,8 +948,6 @@ void *lttng_consumer_thread_poll_fds(void *data)
 	struct lttng_consumer_stream **local_stream = NULL;
 	/* local view of consumer_data.fds_count */
 	int nb_fd = 0;
-	char tmp;
-	int tmp2;
 	struct lttng_consumer_local_data *ctx = data;
 
 	rcu_register_thread();
@@ -1019,11 +1032,14 @@ void *lttng_consumer_thread_poll_fds(void *data)
 		 * low-priority reads.
 		 */
 		if (pollfd[nb_fd].revents & (POLLIN | POLLPRI)) {
+			size_t pipe_readlen;
+			char tmp;
+
 			DBG("consumer_poll_pipe wake up");
-			tmp2 = read(ctx->consumer_poll_pipe[0], &tmp, 1);
-			if (tmp2 < 0) {
-				perror("read consumer poll");
-			}
+			/* Consume 1 byte of pipe data */
+			do {
+				pipe_readlen = read(ctx->consumer_poll_pipe[0], &tmp, 1);
+			} while (pipe_readlen == -1 && errno == EINTR);
 			continue;
 		}
 
@@ -1228,11 +1244,20 @@ end:
 	 */
 	consumer_poll_timeout = LTTNG_CONSUMER_POLL_TIMEOUT;
 
-	/* wake up the polling thread */
-	ret = write(ctx->consumer_poll_pipe[1], "4", 1);
-	if (ret < 0) {
-		perror("poll pipe write");
-	}
+	/*
+	 * Wake-up the other end by writing a null byte in the pipe
+	 * (non-blocking). Important note: Because writing into the
+	 * pipe is non-blocking (and therefore we allow dropping wakeup
+	 * data, as long as there is wakeup data present in the pipe
+	 * buffer to wake up the other end), the other end should
+	 * perform the following sequence for waiting:
+	 * 1) empty the pipe (reads).
+	 * 2) perform update operation.
+	 * 3) wait on the pipe (poll).
+	 */
+	do {
+		ret = write(ctx->consumer_poll_pipe[1], "", 1);
+	} while (ret == -1UL && errno == EINTR);
 	rcu_unregister_thread();
 	return NULL;
 }