Commit 1833b64f authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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perf daemon: Force waipid for all session on SIGCHLD delivery 



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: default avatarIan Rogers <irogers@google.com>
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210320221013.1619613-1-jolsa@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 1a096ae4

tools/perf/builtin-daemon.c

+28 −22
Original line number Diff line number Diff line
@@ -402,17 +402,26 @@ 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));
@@ -426,11 +435,9 @@ static pid_t handle_signalfd(struct daemon *daemon) 
			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");