From 1833b64fee1032d1f48afaa3956bc0ea6b10d5e0 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sat, 20 Mar 2021 23:10:12 +0100 Subject: 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: Ian Rogers Signed-off-by: Jiri Olsa Cc: Alexander Shishkin Cc: Mark Rutland Cc: Michael Petlan Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/20210320221013.1619613-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-daemon.c | 50 +++++++++++++++++++++++++-------------------- 1 file changed, 28 insertions(+), 22 deletions(-) (limited to 'tools/perf') 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 @@ out: 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"); -- cgit v1.2.3