From: "Eric W. Biederman" <ebiederm@xmission.com>
To: linux-kernel@vger.kernel.org
Cc: David Miller <davem@davemloft.net>,
Greg Kroah-Hartman <greg@kroah.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>, bpf <bpf@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jakub Kicinski <kuba@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Gary Lin <GLin@suse.com>, Bruno Meneguele <bmeneg@redhat.com>,
LSM List <linux-security-module@vger.kernel.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH v3 13/16] exit: Factor thread_group_exited out of pidfd_poll
Date: Thu, 2 Jul 2020 11:41:37 -0500 [thread overview]
Message-ID: <20200702164140.4468-13-ebiederm@xmission.com> (raw)
In-Reply-To: <87y2o1swee.fsf_-_@x220.int.ebiederm.org>
Create an independent helper thread_group_exited report return true
when all threads have passed exit_notify in do_exit. AKA all of the
threads are at least zombies and might be dead or completely gone.
Create this helper by taking the logic out of pidfd_poll where
it is already tested, and adding a missing READ_ONCE on
the read of task->exit_state.
I will be changing the user mode driver code to use this same logic
to know when a user mode driver needs to be restarted.
Place the new helper thread_group_exited in kernel/exit.c and
EXPORT it so it can be used by modules.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
include/linux/sched/signal.h | 2 ++
kernel/exit.c | 24 ++++++++++++++++++++++++
kernel/fork.c | 6 +-----
3 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 0ee5e696c5d8..1bad18a1d8ba 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -674,6 +674,8 @@ static inline int thread_group_empty(struct task_struct *p)
#define delay_group_leader(p) \
(thread_group_leader(p) && !thread_group_empty(p))
+extern bool thread_group_exited(struct pid *pid);
+
extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
unsigned long *flags);
diff --git a/kernel/exit.c b/kernel/exit.c
index d3294b611df1..a7f112feb0f6 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1713,6 +1713,30 @@ COMPAT_SYSCALL_DEFINE5(waitid,
}
#endif
+/**
+ * thread_group_exited - check that a thread group has exited
+ * @pid: tgid of thread group to be checked.
+ *
+ * Test if thread group is has exited (all threads are zombies, dead
+ * or completely gone).
+ *
+ * Return: true if the thread group has exited. false otherwise.
+ */
+bool thread_group_exited(struct pid *pid)
+{
+ struct task_struct *task;
+ bool exited;
+
+ rcu_read_lock();
+ task = pid_task(pid, PIDTYPE_PID);
+ exited = !task ||
+ (READ_ONCE(task->exit_state) && thread_group_empty(task));
+ rcu_read_unlock();
+
+ return exited;
+}
+EXPORT_SYMBOL(thread_group_exited);
+
__weak void abort(void)
{
BUG();
diff --git a/kernel/fork.c b/kernel/fork.c
index 142b23645d82..bf215af7a904 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1787,22 +1787,18 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
*/
static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
{
- struct task_struct *task;
struct pid *pid = file->private_data;
__poll_t poll_flags = 0;
poll_wait(file, &pid->wait_pidfd, pts);
- rcu_read_lock();
- task = pid_task(pid, PIDTYPE_PID);
/*
* Inform pollers only when the whole thread group exits.
* If the thread group leader exits before all other threads in the
* group, then poll(2) should block, similar to the wait(2) family.
*/
- if (!task || (task->exit_state && thread_group_empty(task)))
+ if (thread_group_exited(pid))
poll_flags = EPOLLIN | EPOLLRDNORM;
- rcu_read_unlock();
return poll_flags;
}
--
2.25.0
next prev parent reply other threads:[~2020-07-02 16:48 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200625095725.GA3303921@kroah.com>
[not found] ` <778297d2-512a-8361-cf05-42d9379e6977@i-love.sakura.ne.jp>
[not found] ` <20200625120725.GA3493334@kroah.com>
[not found] ` <20200625.123437.2219826613137938086.davem@davemloft.net>
[not found] ` <CAHk-=whuTwGHEPjvtbBvneHHXeqJC=q5S09mbPnqb=Q+MSPMag@mail.gmail.com>
[not found] ` <87pn9mgfc2.fsf_-_@x220.int.ebiederm.org>
[not found] ` <87y2oac50p.fsf@x220.int.ebiederm.org>
2020-06-29 19:55 ` [PATCH v2 00/15] Make the user mode driver code a better citizen Eric W. Biederman
2020-06-29 19:56 ` [PATCH v2 01/15] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-06-29 19:57 ` [PATCH v2 02/15] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-06-29 19:57 ` [PATCH v2 03/15] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-06-29 19:59 ` [PATCH v2 04/15] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-06-29 20:00 ` [PATCH v2 05/15] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-06-30 16:58 ` Linus Torvalds
2020-07-01 17:18 ` Eric W. Biederman
2020-07-01 17:42 ` Alexei Starovoitov
2020-06-29 20:01 ` [PATCH v2 06/15] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-06-29 20:02 ` [PATCH v2 07/15] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-06-29 20:03 ` [PATCH v2 08/15] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-06-29 20:03 ` [PATCH v2 09/15] umh: Stop calling do_execve_file Eric W. Biederman
2020-06-29 20:04 ` [PATCH v2 10/15] exec: Remove do_execve_file Eric W. Biederman
2020-06-30 5:43 ` Christoph Hellwig
2020-06-30 12:14 ` Eric W. Biederman
2020-06-30 13:38 ` Christoph Hellwig
2020-06-30 14:28 ` Eric W. Biederman
2020-06-30 16:55 ` Alexei Starovoitov
2020-06-29 20:05 ` [PATCH v2 11/15] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-06-29 20:06 ` [PATCH v2 12/15] umd: Track user space drivers with struct pid Eric W. Biederman
2020-06-29 20:06 ` [PATCH v2 13/15] bpfilter: Take advantage of the facilities of " Eric W. Biederman
2020-06-29 20:07 ` [PATCH v2 14/15] umd: Remove exit_umh Eric W. Biederman
2020-06-29 20:08 ` [PATCH v2 15/15] umd: Stop using split_argv Eric W. Biederman
2020-06-29 22:12 ` [PATCH v2 00/15] Make the user mode driver code a better citizen Alexei Starovoitov
2020-06-30 1:13 ` Eric W. Biederman
2020-06-30 6:16 ` Tetsuo Handa
2020-06-30 12:29 ` Eric W. Biederman
2020-06-30 13:21 ` Tetsuo Handa
2020-07-02 13:08 ` Eric W. Biederman
2020-07-02 13:40 ` Tetsuo Handa
2020-07-02 16:02 ` Eric W. Biederman
2020-07-03 13:19 ` Tetsuo Handa
2020-07-03 22:25 ` Eric W. Biederman
2020-07-04 6:57 ` Tetsuo Handa
2020-07-08 4:46 ` Eric W. Biederman
2020-06-30 16:52 ` Alexei Starovoitov
2020-07-01 17:12 ` Eric W. Biederman
2020-07-02 16:40 ` [PATCH v3 00/16] " Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 01/16] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 02/16] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 03/16] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 04/16] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 05/16] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 06/16] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 07/16] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 08/16] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 09/16] umh: Stop calling do_execve_file Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 10/16] exec: Remove do_execve_file Eric W. Biederman
2020-07-08 6:35 ` Luis Chamberlain
2020-07-08 12:41 ` Luis Chamberlain
2020-07-08 13:08 ` Eric W. Biederman
2020-07-08 13:32 ` Luis Chamberlain
2020-07-12 21:02 ` Pavel Machek
2020-07-02 16:41 ` [PATCH v3 11/16] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 12/16] umd: Track user space drivers with struct pid Eric W. Biederman
2020-07-02 16:41 ` Eric W. Biederman [this message]
2020-07-03 20:30 ` [PATCH v3 13/16] exit: Factor thread_group_exited out of pidfd_poll Alexei Starovoitov
2020-07-03 21:37 ` Eric W. Biederman
2020-07-04 0:03 ` Alexei Starovoitov
2020-07-04 15:50 ` Christian Brauner
2020-07-07 17:09 ` Eric W. Biederman
2020-07-08 0:05 ` Daniel Borkmann
2020-07-08 3:50 ` Eric W. Biederman
2020-07-04 16:00 ` Christian Brauner
2020-07-02 16:41 ` [PATCH v3 14/16] bpfilter: Take advantage of the facilities of struct pid Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 15/16] umd: Remove exit_umh Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 16/16] umd: Stop using split_argv Eric W. Biederman
2020-07-02 23:51 ` [PATCH v3 00/16] Make the user mode driver code a better citizen Tetsuo Handa
2020-07-09 22:05 ` [merged][PATCH " Eric W. Biederman
2020-07-14 19:42 ` Alexei Starovoitov
2020-07-08 5:20 ` [PATCH v2 00/15] " Luis Chamberlain
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=20200702164140.4468-13-ebiederm@xmission.com \
--to=ebiederm@xmission.com \
--cc=GLin@suse.com \
--cc=akpm@linux-foundation.org \
--cc=alexei.starovoitov@gmail.com \
--cc=ast@kernel.org \
--cc=bmeneg@redhat.com \
--cc=bpf@vger.kernel.org \
--cc=casey@schaufler-ca.com \
--cc=christian.brauner@ubuntu.com \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=greg@kroah.com \
--cc=keescook@chromium.org \
--cc=kuba@kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=mcgrof@kernel.org \
--cc=penguin-kernel@i-love.sakura.ne.jp \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=yamada.masahiro@socionext.com \
/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).