From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>,
lkml <linux-kernel@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Namhyung Kim <namhyung@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Michael Petlan <mpetlan@redhat.com>
Subject: Re: [PATCH 1/2] perf daemon: Force waipid for all session on SIGCHLD delivery
Date: Wed, 24 Mar 2021 10:24:46 -0300 [thread overview]
Message-ID: <YFs9nkXP46Olg5mZ@kernel.org> (raw)
In-Reply-To: <20210320221013.1619613-1-jolsa@kernel.org>
Em Sat, Mar 20, 2021 at 11:10:12PM +0100, Jiri Olsa escreveu:
> 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.
Thanks, applied.
- Arnaldo
> Reported-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Jiri Olsa <jolsa@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
>
--
- Arnaldo
prev parent reply other threads:[~2021-03-24 13:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-20 22:10 [PATCH 1/2] perf daemon: Force waipid for all session on SIGCHLD delivery Jiri Olsa
2021-03-20 22:10 ` [PATCH 2/2] perf daemon: Return from kill functions Jiri Olsa
2021-03-24 13:24 ` Arnaldo Carvalho de Melo [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YFs9nkXP46Olg5mZ@kernel.org \
--to=acme@kernel.org \
--cc=a.p.zijlstra@chello.nl \
--cc=alexander.shishkin@linux.intel.com \
--cc=irogers@google.com \
--cc=jolsa@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@kernel.org \
--cc=mpetlan@redhat.com \
--cc=namhyung@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).