perf daemon: Add server socket support

Add support to create a server socket that listens for client commands
and processes them.

This patch adds only the core support, all commands using this
functionality are coming in the following patches.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-5-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index ce0373f..495e4ff 100644 (file)
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -1,12 +1,19 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <internal/lib.h>
 #include <subcmd/parse-options.h>
+#include <api/fd/array.h>
 #include <linux/limits.h>
+#include <linux/string.h>
 #include <string.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <poll.h>
 #include "builtin.h"
 #include "perf.h"
 #include "debug.h"
@@ -37,6 +44,92 @@ static void sig_handler(int sig __maybe_unused)
        done = true;
 }
 
+static int setup_server_socket(struct daemon *daemon)
+{
+       struct sockaddr_un addr;
+       char path[PATH_MAX];
+       int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+
+       if (fd < 0) {
+               fprintf(stderr, "socket: %s\n", strerror(errno));
+               return -1;
+       }
+
+       if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {
+               perror("failed: fcntl FD_CLOEXEC");
+               close(fd);
+               return -1;
+       }
+
+       scnprintf(path, sizeof(path), "%s/control", daemon->base);
+
+       if (strlen(path) + 1 >= sizeof(addr.sun_path)) {
+               pr_err("failed: control path too long '%s'\n", path);
+               close(fd);
+               return -1;
+       }
+
+       memset(&addr, 0, sizeof(addr));
+       addr.sun_family = AF_UNIX;
+
+       strlcpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
+       unlink(path);
+
+       if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+               perror("failed: bind");
+               close(fd);
+               return -1;
+       }
+
+       if (listen(fd, 1) == -1) {
+               perror("failed: listen");
+               close(fd);
+               return -1;
+       }
+
+       return fd;
+}
+
+union cmd {
+       int cmd;
+};
+
+static int handle_server_socket(struct daemon *daemon __maybe_unused, int sock_fd)
+{
+       int ret = -1, fd;
+       FILE *out = NULL;
+       union cmd cmd;
+
+       fd = accept(sock_fd, NULL, NULL);
+       if (fd < 0) {
+               perror("failed: accept");
+               return -1;
+       }
+
+       if (sizeof(cmd) != readn(fd, &cmd, sizeof(cmd))) {
+               perror("failed: read");
+               goto out;
+       }
+
+       out = fdopen(fd, "w");
+       if (!out) {
+               perror("failed: fdopen");
+               goto out;
+       }
+
+       switch (cmd.cmd) {
+       default:
+               break;
+       }
+
+       fclose(out);
+out:
+       /* If out is defined, then fd is closed via fclose. */
+       if (!out)
+               close(fd);
+       return ret;
+}
+
 static void daemon__exit(struct daemon *daemon)
 {
        free(daemon->config_real);
@@ -77,6 +170,9 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
                OPT_PARENT(parent_options),
                OPT_END()
        };
+       int sock_fd = -1;
+       int sock_pos;
+       struct fdarray fda;
        int err = 0;
 
        argc = parse_options(argc, argv, start_options, daemon_usage, 0);
@@ -93,15 +189,34 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
 
        pr_info("daemon started (pid %d)\n", getpid());
 
+       fdarray__init(&fda, 1);
+
+       sock_fd = setup_server_socket(daemon);
+       if (sock_fd < 0)
+               goto out;
+
+       sock_pos = fdarray__add(&fda, sock_fd, POLLIN|POLLERR|POLLHUP, 0);
+       if (sock_pos < 0)
+               goto out;
+
        signal(SIGINT, sig_handler);
        signal(SIGTERM, sig_handler);
 
        while (!done && !err) {
-               sleep(1);
+               if (fdarray__poll(&fda, -1)) {
+                       if (fda.entries[sock_pos].revents & POLLIN)
+                               err = handle_server_socket(daemon, sock_fd);
+               }
        }
 
+out:
+       fdarray__exit(&fda);
+
        daemon__exit(daemon);
 
+       if (sock_fd != -1)
+               close(sock_fd);
+
        pr_info("daemon exited\n");
        fclose(daemon->out);
        return err;