X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Fevent-notifier-notification.c;h=96b91a9ab0b84d2bd85b4531b28d18e9f1b11e33;hb=cd61d9bfa5fd334b086831dcbdec63da6c0d1a16;hp=844438f2378a329763a90d5f49e431062d89253b;hpb=b9f82a28cface9fa168149252d560a7bade056c9;p=lttng-ust.git

diff --git a/liblttng-ust/event-notifier-notification.c b/liblttng-ust/event-notifier-notification.c
index 844438f2..96b91a9a 100644
--- a/liblttng-ust/event-notifier-notification.c
+++ b/liblttng-ust/event-notifier-notification.c
@@ -1,38 +1,39 @@
 /*
- * event-notifier-notification.c
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
  * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #define _LGPL_SOURCE
 
 #include <assert.h>
-#include <byteswap.h>
 #include <errno.h>
 #include <lttng/ust-events.h>
+#include <lttng/ust-endian.h>
 #include <usterr-signal-safe.h>
 
 #include "../libmsgpack/msgpack.h"
 #include "lttng-bytecode.h"
-#include "share.h"
+#include "ust-share.h"
+
+/*
+ * We want this write to be atomic AND non-blocking, meaning that we
+ * want to write either everything OR nothing.
+ * According to `pipe(7)`, writes that are less than `PIPE_BUF` bytes must be
+ * atomic, so we bound the capture buffer size to the `PIPE_BUF` minus the size
+ * of the notification struct we are sending alongside the capture buffer.
+ */
+#define CAPTURE_BUFFER_SIZE \
+	(PIPE_BUF - sizeof(struct lttng_ust_event_notifier_notification) - 1)
+
+struct lttng_event_notifier_notification {
+	int notification_fd;
+	uint64_t event_notifier_token;
+	uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
+	struct lttng_msgpack_writer writer;
+	bool has_captures;
+};
 
-static
-void capture_enum(struct lttng_msgpack_writer *writer,
-		struct lttng_interpreter_output *output) __attribute__ ((unused));
 static
 void capture_enum(struct lttng_msgpack_writer *writer,
 		struct lttng_interpreter_output *output)
@@ -155,9 +156,6 @@ uint64_t capture_sequence_element_unsigned(uint8_t *ptr,
 	return value;
 }
 
-static
-void capture_sequence(struct lttng_msgpack_writer *writer,
-		struct lttng_interpreter_output *output) __attribute__ ((unused));
 static
 void capture_sequence(struct lttng_msgpack_writer *writer,
 		struct lttng_interpreter_output *output)
@@ -210,30 +208,144 @@ void capture_sequence(struct lttng_msgpack_writer *writer,
 	lttng_msgpack_end_array(writer);
 }
 
-void lttng_event_notifier_notification_send(
+static
+void notification_init(struct lttng_event_notifier_notification *notif,
 		struct lttng_event_notifier *event_notifier)
 {
+	struct lttng_msgpack_writer *writer = &notif->writer;
+
+	notif->event_notifier_token = event_notifier->user_token;
+	notif->notification_fd = event_notifier->group->notification_fd;
+	notif->has_captures = false;
+
+	if (event_notifier->num_captures > 0) {
+		lttng_msgpack_writer_init(writer, notif->capture_buf,
+				CAPTURE_BUFFER_SIZE);
+
+		lttng_msgpack_begin_array(writer, event_notifier->num_captures);
+		notif->has_captures = true;
+	}
+}
+
+static
+void notification_append_capture(
+		struct lttng_event_notifier_notification *notif,
+		struct lttng_interpreter_output *output)
+{
+	struct lttng_msgpack_writer *writer = &notif->writer;
+
+	switch (output->type) {
+	case LTTNG_INTERPRETER_TYPE_S64:
+		lttng_msgpack_write_signed_integer(writer, output->u.s);
+		break;
+	case LTTNG_INTERPRETER_TYPE_U64:
+		lttng_msgpack_write_unsigned_integer(writer, output->u.u);
+		break;
+	case LTTNG_INTERPRETER_TYPE_DOUBLE:
+		lttng_msgpack_write_double(writer, output->u.d);
+		break;
+	case LTTNG_INTERPRETER_TYPE_STRING:
+		lttng_msgpack_write_str(writer, output->u.str.str);
+		break;
+	case LTTNG_INTERPRETER_TYPE_SEQUENCE:
+		capture_sequence(writer, output);
+		break;
+	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
+	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
+		capture_enum(writer, output);
+		break;
+	default:
+		abort();
+	}
+}
+
+static
+void notification_append_empty_capture(
+		struct lttng_event_notifier_notification *notif)
+{
+	lttng_msgpack_write_nil(&notif->writer);
+}
+
+static void record_error(struct lttng_event_notifier *event_notifier)
+{
+	struct lttng_event_notifier_group *event_notifier_group =
+			event_notifier->group;
+	struct lttng_counter *error_counter;
+	size_t dimension_index[1];
+	int ret;
+
+	error_counter = CMM_LOAD_SHARED(event_notifier_group->error_counter);
 	/*
-	 * We want this write to be atomic AND non-blocking, meaning that we
-	 * want to write either everything OR nothing.
-	 * According to `pipe(7)`, writes that are smaller that the `PIPE_BUF`
-	 * value must be atomic, so we assert that the message we send is less
-	 * than PIPE_BUF.
+	 * load-acquire paired with store-release orders creation of the
+	 * error counter and setting error_counter_len before the
+	 * error_counter is used.
+	 * Currently a full memory barrier is used, which could be
+	 * turned into acquire-release barriers.
 	 */
-	struct lttng_ust_event_notifier_notification notif;
+	cmm_smp_mb();
+	/* This group may not have an error counter attached to it. */
+	if (!error_counter)
+		return;
+
+	dimension_index[0] = event_notifier->error_counter_index;
+	ret = event_notifier_group->error_counter->ops->counter_add(
+			error_counter->counter, dimension_index, 1);
+	if (ret)
+		WARN_ON_ONCE(1);
+}
+
+static
+void notification_send(struct lttng_event_notifier_notification *notif,
+		struct lttng_event_notifier *event_notifier)
+{
 	ssize_t ret;
+	size_t content_len;
+	int iovec_count = 1;
+	struct lttng_ust_event_notifier_notification ust_notif = {0};
+	struct iovec iov[2];
+
+	assert(notif);
+
+	ust_notif.token = event_notifier->user_token;
+
+	/*
+	 * Prepare sending the notification from multiple buffers using an
+	 * array of `struct iovec`. The first buffer of the vector is
+	 * notification structure itself and is always present.
+	 */
+	iov[0].iov_base = &ust_notif;
+	iov[0].iov_len = sizeof(ust_notif);
+
+	if (notif->has_captures) {
+		/*
+		 * If captures were requested, the second buffer of the array
+		 * is the capture buffer.
+		 */
+		assert(notif->writer.buffer);
+		content_len = notif->writer.write_pos - notif->writer.buffer;
+
+		assert(content_len > 0 && content_len <= CAPTURE_BUFFER_SIZE);
+
+		iov[1].iov_base = notif->capture_buf;
+		iov[1].iov_len = content_len;
 
-	assert(event_notifier);
-	assert(event_notifier->group);
-	assert(sizeof(notif) <= PIPE_BUF);
+		iovec_count++;
+	} else {
+		content_len = 0;
+	}
 
-	notif.token = event_notifier->user_token;
+	/*
+	 * Update the capture buffer size so that receiver of the buffer will
+	 * know how much to expect.
+	 */
+	ust_notif.capture_buf_size = content_len;
 
-	ret = patient_write(event_notifier->group->notification_fd, &notif,
-		sizeof(notif));
+	/* Send all the buffers. */
+	ret = ust_patient_writev(notif->notification_fd, iov, iovec_count);
 	if (ret == -1) {
 		if (errno == EAGAIN) {
-			DBG("Cannot send event notifier notification without blocking: %s",
+			record_error(event_notifier);
+			DBG("Cannot send event_notifier notification without blocking: %s",
 				strerror(errno));
 		} else {
 			DBG("Error to sending event notifier notification: %s",
@@ -242,3 +354,43 @@ void lttng_event_notifier_notification_send(
 		}
 	}
 }
+
+void lttng_event_notifier_notification_send(
+		struct lttng_event_notifier *event_notifier,
+		const char *stack_data)
+{
+	/*
+	 * This function is called from the probe, we must do dynamic
+	 * allocation in this context.
+	 */
+	struct lttng_event_notifier_notification notif = {0};
+
+	notification_init(&notif, event_notifier);
+
+	if (caa_unlikely(!cds_list_empty(&event_notifier->capture_bytecode_runtime_head))) {
+		struct lttng_bytecode_runtime *capture_bc_runtime;
+
+		/*
+		 * Iterate over all the capture bytecodes. If the interpreter
+		 * functions returns successfully, append the value of the
+		 * `output` parameter to the capture buffer. If the interpreter
+		 * fails, append an empty capture to the buffer.
+		 */
+		cds_list_for_each_entry(capture_bc_runtime,
+				&event_notifier->capture_bytecode_runtime_head, node) {
+			struct lttng_interpreter_output output;
+
+			if (capture_bc_runtime->interpreter_funcs.capture(capture_bc_runtime,
+					stack_data, &output) & LTTNG_INTERPRETER_RECORD_FLAG)
+				notification_append_capture(&notif, &output);
+			else
+				notification_append_empty_capture(&notif);
+		}
+	}
+
+	/*
+	 * Send the notification (including the capture buffer) to the
+	 * sessiond.
+	 */
+	notification_send(&notif, event_notifier);
+}