If we don't process SIGCHLD before another comes, we will
see just one SIGCHLD as a result. In this case current code
will miss exit notification for a session and wait forever.
Adding extra waitpid check for all sessions when SIGCHLD
is received, to make sure we don't miss any session exit.
Also fix close condition for signal_fd.
Reported-by: Ian Rogers <irog...@google.com>
Signed-off-by: Jiri Olsa <jo...@kernel.org>
---
tools/perf/builtin-daemon.c | 50 +++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 22 deletions(-)
diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index ace8772a4f03..4697493842f5 100644
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -402,35 +402,42 @@ static pid_t handle_signalfd(struct daemon *daemon)
int status;
pid_t pid;
+ /*
+ * Take signal fd data as pure signal notification and check all
+ * the sessions state. The reason is that multiple signals can get
+ * coalesced in kernel and we can receive only single signal even
+ * if multiple SIGCHLD were generated.
+ */
err = read(daemon->signal_fd, &si, sizeof(struct signalfd_siginfo));
- if (err != sizeof(struct signalfd_siginfo))
+ if (err != sizeof(struct signalfd_siginfo)) {
+ pr_err("failed to read signal fd\n");
return -1;
+ }
list_for_each_entry(session, &daemon->sessions, list) {
+ if (session->pid == -1)
+ continue;
- if (session->pid != (int) si.ssi_pid)
+ pid = waitpid(session->pid, &status, WNOHANG);
+ if (pid <= 0)
continue;
- pid = waitpid(session->pid, &status, 0);
- if (pid == session->pid) {
- if (WIFEXITED(status)) {
- pr_info("session '%s' exited, status=%d\n",
- session->name, WEXITSTATUS(status));
- } else if (WIFSIGNALED(status)) {
- pr_info("session '%s' killed (signal %d)\n",
- session->name, WTERMSIG(status));
- } else if (WIFSTOPPED(status)) {
- pr_info("session '%s' stopped (signal %d)\n",
- session->name, WSTOPSIG(status));
- } else {
- pr_info("session '%s' Unexpected status
(0x%x)\n",
- session->name, status);
- }
+ if (WIFEXITED(status)) {
+ pr_info("session '%s' exited, status=%d\n",
+ session->name, WEXITSTATUS(status));
+ } else if (WIFSIGNALED(status)) {
+ pr_info("session '%s' killed (signal %d)\n",
+ session->name, WTERMSIG(status));
+ } else if (WIFSTOPPED(status)) {
+ pr_info("session '%s' stopped (signal %d)\n",
+ session->name, WSTOPSIG(status));
+ } else {
+ pr_info("session '%s' Unexpected status (0x%x)\n",
+ session->name, status);
}
session->state = KILL;
session->pid = -1;
- return pid;
}
return 0;
@@ -443,7 +450,6 @@ static int daemon_session__wait(struct daemon_session
*session, struct daemon *d
.fd = daemon->signal_fd,
.events = POLLIN,
};
- pid_t wpid = 0, pid = session->pid;
time_t start;
start = time(NULL);
@@ -452,7 +458,7 @@ static int daemon_session__wait(struct daemon_session
*session, struct daemon *d
int err = poll(&pollfd, 1, 1000);
if (err > 0) {
- wpid = handle_signalfd(daemon);
+ handle_signalfd(daemon);
} else if (err < 0) {
perror("failed: poll\n");
return -1;
@@ -460,7 +466,7 @@ static int daemon_session__wait(struct daemon_session
*session, struct daemon *d
if (start + secs < time(NULL))
return -1;
- } while (wpid != pid);
+ } while (session->pid != -1);
return 0;
}
@@ -1344,7 +1350,7 @@ static int __cmd_start(struct daemon *daemon, struct
option parent_options[],
close(sock_fd);
if (conf_fd != -1)
close(conf_fd);
- if (conf_fd != -1)
+ if (signal_fd != -1)
close(signal_fd);
pr_info("daemon exited\n");
--
2.30.2
