[PATCH v2 02/11] perf evlist: implement control command handling functions

Alexey Budankov
2020-05-06T18:19:28Z

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

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
tools/perf/util/evlist.c | 100 +++++++++++++++++++++++++++++++++++++++
tools/perf/util/evlist.h | 12 +++++
2 files changed, 112 insertions(+)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 2db4bedc4f81..e086c846ef3a 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1707,3 +1707,103 @@ struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list,
}
return leader;
}
+
+int perf_evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack)
+{
+ if (ctl_fd == -1) {
+ pr_debug("Control descriptor is not initialized\n");
+ return 0;
+ }
+
+ evlist->ctl_fd_pos = perf_evlist__add_pollfd(&evlist->core, ctl_fd, NULL, POLLIN);
+ 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 = ctl_fd;
+ evlist->ctl_fd_ack = ctl_fd_ack;
+
+ return 0;
+}
+
+int perf_evlist__finalize_ctlfd(struct evlist *evlist)
+{
+ if (evlist->ctl_fd_pos == -1)
+ return 0;
+
+ evlist->core.pollfd.entries[evlist->ctl_fd_pos].fd = -1;
+ evlist->ctl_fd_pos = -1;
+ evlist->ctl_fd_ack = -1;
+ evlist->ctl_fd = -1;
+
+ return 0;
+}
+
+static int perf_evlist__ctlfd_recv(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
+{
+ int err;
+ char buf[2];
+
+ err = read(evlist->ctl_fd, &buf, sizeof(buf));
+ if (err > 0)
+ *cmd = buf[0];
+ else if (err == -1)
+ pr_err("Failed to read from ctlfd %d: %m\n", evlist->ctl_fd);
+
+ return err;
+}
+
+static int perf_evlist__ctlfd_ack(struct evlist *evlist)
+{
+ int err;
+ char buf[2] = {CTL_CMD_ACK, '\n'};
+
+ if (evlist->ctl_fd_ack == -1)
+ return 0;
+
+ err = write(evlist->ctl_fd_ack, buf, sizeof(buf));
+ if (err == -1)
+ pr_err("failed to write to ctl_ack_fd %d: %m\n", evlist->ctl_fd_ack);
+
+ return err;
+}
+
+int perf_evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
+{
+ int err = 0;
+ int ctlfd_pos = evlist->ctl_fd_pos;
+ struct pollfd *entries = evlist->core.pollfd.entries;
+
+ if (!entries[ctlfd_pos].revents)
+ return 0;
+
+ if (entries[ctlfd_pos].revents & POLLIN) {
+ err = perf_evlist__ctlfd_recv(evlist, cmd);
+ if (err > 0) {
+ switch (*cmd) {
+ case CTL_CMD_ENABLE:
+ evlist__enable(evlist);
+ break;
+ case CTL_CMD_DISABLE:
+ evlist__disable(evlist);
+ break;
+ case CTL_CMD_ACK:
+ case CTL_CMD_UNSUPPORTED:
+ default:
+ pr_debug("ctlfd: unsupported %d\n", *cmd);
+ break;
+ }
+ if (!(*cmd == CTL_CMD_ACK || *cmd == CTL_CMD_UNSUPPORTED))
+ perf_evlist__ctlfd_ack(evlist);
+ }
+ }
+
+ if (entries[ctlfd_pos].revents & (POLLHUP | POLLERR))
+ perf_evlist__finalize_ctlfd(evlist);
+ else
+ entries[ctlfd_pos].revents = 0;
+
+ return err;
+}
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 62f259d89b41..84386850c290 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -358,4 +358,16 @@ void perf_evlist__force_leader(struct evlist *evlist);
struct evsel *perf_evlist__reset_weak_group(struct evlist *evlist,
struct evsel *evsel,
bool close);
+
+enum evlist_ctl_cmd {
+ CTL_CMD_UNSUPPORTED = 0,
+ CTL_CMD_ENABLE = 'e',
+ CTL_CMD_DISABLE = 'd',
+ CTL_CMD_ACK = 'a'
+};
+
+int perf_evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack);
+int perf_evlist__finalize_ctlfd(struct evlist *evlist);
+int perf_evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd);
+
#endif /* __PERF_EVLIST_H */
--
2.24.1