perf evlist: Implement control command handling functions

Implement functions of initialization, finalization and processing of
control command messages coming from control file descriptors.

Allocate control file descriptor as descriptor at struct pollfd object
of evsel_list for atomic poll() operation.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/62518ceb-1cc9-2aba-593b-55408d07c1bf@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 82d00255d4a6..e3fa3bf7498a 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1726,3 +1726,143 @@ struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list,
 	}
 	return leader;
 }
+
+int evlist__initialize_ctlfd(struct evlist *evlist, int fd, int ack)
+{
+	if (fd == -1) {
+		pr_debug("Control descriptor is not initialized\n");
+		return 0;
+	}
+
+	evlist->ctl_fd.pos = perf_evlist__add_pollfd(&evlist->core, fd, NULL, POLLIN,
+						     fdarray_flag__nonfilterable);
+	if (evlist->ctl_fd.pos < 0) {
+		evlist->ctl_fd.pos = -1;
+		pr_err("Failed to add ctl fd entry: %m\n");
+		return -1;
+	}
+
+	evlist->ctl_fd.fd = fd;
+	evlist->ctl_fd.ack = ack;
+
+	return 0;
+}
+
+bool evlist__ctlfd_initialized(struct evlist *evlist)
+{
+	return evlist->ctl_fd.pos >= 0;
+}
+
+int evlist__finalize_ctlfd(struct evlist *evlist)
+{
+	struct pollfd *entries = evlist->core.pollfd.entries;
+
+	if (!evlist__ctlfd_initialized(evlist))
+		return 0;
+
+	entries[evlist->ctl_fd.pos].fd = -1;
+	entries[evlist->ctl_fd.pos].events = 0;
+	entries[evlist->ctl_fd.pos].revents = 0;
+
+	evlist->ctl_fd.pos = -1;
+	evlist->ctl_fd.ack = -1;
+	evlist->ctl_fd.fd = -1;
+
+	return 0;
+}
+
+static int evlist__ctlfd_recv(struct evlist *evlist, enum evlist_ctl_cmd *cmd,
+			      char *cmd_data, size_t data_size)
+{
+	int err;
+	char c;
+	size_t bytes_read = 0;
+
+	memset(cmd_data, 0, data_size);
+	data_size--;
+
+	do {
+		err = read(evlist->ctl_fd.fd, &c, 1);
+		if (err > 0) {
+			if (c == '\n' || c == '\0')
+				break;
+			cmd_data[bytes_read++] = c;
+			if (bytes_read == data_size)
+				break;
+		} else {
+			if (err == -1)
+				pr_err("Failed to read from ctlfd %d: %m\n", evlist->ctl_fd.fd);
+			break;
+		}
+	} while (1);
+
+	pr_debug("Message from ctl_fd: \"%s%s\"\n", cmd_data,
+		 bytes_read == data_size ? "" : c == '\n' ? "\\n" : "\\0");
+
+	if (err > 0) {
+		if (!strncmp(cmd_data, EVLIST_CTL_CMD_ENABLE_TAG,
+			     (sizeof(EVLIST_CTL_CMD_ENABLE_TAG)-1))) {
+			*cmd = EVLIST_CTL_CMD_ENABLE;
+		} else if (!strncmp(cmd_data, EVLIST_CTL_CMD_DISABLE_TAG,
+				    (sizeof(EVLIST_CTL_CMD_DISABLE_TAG)-1))) {
+			*cmd = EVLIST_CTL_CMD_DISABLE;
+		}
+	}
+
+	return err;
+}
+
+static int evlist__ctlfd_ack(struct evlist *evlist)
+{
+	int err;
+
+	if (evlist->ctl_fd.ack == -1)
+		return 0;
+
+	err = write(evlist->ctl_fd.ack, EVLIST_CTL_CMD_ACK_TAG,
+		    sizeof(EVLIST_CTL_CMD_ACK_TAG));
+	if (err == -1)
+		pr_err("failed to write to ctl_ack_fd %d: %m\n", evlist->ctl_fd.ack);
+
+	return err;
+}
+
+int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
+{
+	int err = 0;
+	char cmd_data[EVLIST_CTL_CMD_MAX_LEN];
+	int ctlfd_pos = evlist->ctl_fd.pos;
+	struct pollfd *entries = evlist->core.pollfd.entries;
+
+	if (!evlist__ctlfd_initialized(evlist) || !entries[ctlfd_pos].revents)
+		return 0;
+
+	if (entries[ctlfd_pos].revents & POLLIN) {
+		err = evlist__ctlfd_recv(evlist, cmd, cmd_data,
+					 EVLIST_CTL_CMD_MAX_LEN);
+		if (err > 0) {
+			switch (*cmd) {
+			case EVLIST_CTL_CMD_ENABLE:
+				evlist__enable(evlist);
+				break;
+			case EVLIST_CTL_CMD_DISABLE:
+				evlist__disable(evlist);
+				break;
+			case EVLIST_CTL_CMD_ACK:
+			case EVLIST_CTL_CMD_UNSUPPORTED:
+			default:
+				pr_debug("ctlfd: unsupported %d\n", *cmd);
+				break;
+			}
+			if (!(*cmd == EVLIST_CTL_CMD_ACK || *cmd == EVLIST_CTL_CMD_UNSUPPORTED))
+				evlist__ctlfd_ack(evlist);
+		}
+	}
+
+	if (entries[ctlfd_pos].revents & (POLLHUP | POLLERR))
+		evlist__finalize_ctlfd(evlist);
+	else
+		entries[ctlfd_pos].revents = 0;
+
+	return err;
+}